rules: Refactoring and minor improvements

Compared to the previous commit, the action graphs for just
and its unit tests are unchanged.
- Git hash of action graph for ["",""]:
    c6e75f17abd7ffaab6ff9bb725ad67ec0bf6c973
- Git hash of action graph for ["test/buildtool","TESTS"]:
    8063dfb3dd7daa9ae01d95c177e14946f785c57e

Refactor:
- "local cflags" to "private-cflags"
- "local defines" to "private-defines"
- "link externals" to "private-ldflags"
- "deps" to "private-deps" for (test) binaries
- "proto" to "private-proto" for binaries

Improvements:
- consistent variable declaration order:
    OS, ARCH, HOST_ARCH, TARGET_ARCH,
    CC, CXX, CFLAGS, CXXFLAGS, ADD_CFLAGS, ADD_CXXFLAGS,
    AR, ENV, PATH
- use fields close to their definition (in RULES)
- use common expression for binaries and test binaries
- split expression "flags" and "compiler"
  ... to separate ones for CC and CXX.
- rename "transition" to "deps-transition"
  ... to avoid conflicts with other transitions.
- support "defaults-transition" for CC expressions

Implement:
- "cflags" for libraries
- "private-cflags" for (test) binaries
- "private-defines" for test binaries
- "private-ldflags" for test binaries
- (public) "defines" for libraries

8 files changed, 662 insertions, 449 deletions

diff --git a/rules/CC/EXPRESSIONS b/rules/CC/EXPRESSIONS
index 7871acef..81ac1fd8 100644
--- a/rules/CC/EXPRESSIONS
+++ b/rules/CC/EXPRESSIONS
@@ -1,59 +1,98 @@
 { "default-CC":
-  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
     { "type": "join"
     , "$1":
       { "type": "let*"
-      , "bindings": [["fieldname", "defaults"], ["provider", "CC"]]
+      , "bindings":
+        [ ["fieldname", "defaults"]
+        , ["provider", "CC"]
+        , [ "transition"
+          , {"type": "var", "name": "defaults-transition", "default": null}
+          ]
+        ]
       , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
       }
     }
   }
 , "default-CXX":
-  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
     { "type": "join"
     , "$1":
       { "type": "let*"
-      , "bindings": [["fieldname", "defaults"], ["provider", "CXX"]]
+      , "bindings":
+        [ ["fieldname", "defaults"]
+        , ["provider", "CXX"]
+        , [ "transition"
+          , {"type": "var", "name": "defaults-transition", "default": null}
+          ]
+        ]
       , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
       }
     }
   }
 , "default-AR":
-  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
     { "type": "join"
     , "$1":
       { "type": "let*"
-      , "bindings": [["fieldname", "defaults"], ["provider", "AR"]]
+      , "bindings":
+        [ ["fieldname", "defaults"]
+        , ["provider", "AR"]
+        , [ "transition"
+          , {"type": "var", "name": "defaults-transition", "default": null}
+          ]
+        ]
       , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
       }
     }
   }
 , "default-CFLAGS":
-  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
     { "type": "let*"
-    , "bindings": [["fieldname", "defaults"], ["provider", "CFLAGS"]]
+    , "bindings":
+      [ ["fieldname", "defaults"]
+      , ["provider", "CFLAGS"]
+      , [ "transition"
+        , {"type": "var", "name": "defaults-transition", "default": null}
+        ]
+      ]
     , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
     }
   }
 , "default-CXXFLAGS":
-  { "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
     { "type": "let*"
-    , "bindings": [["fieldname", "defaults"], ["provider", "CXXFLAGS"]]
+    , "bindings":
+      [ ["fieldname", "defaults"]
+      , ["provider", "CXXFLAGS"]
+      , [ "transition"
+        , {"type": "var", "name": "defaults-transition", "default": null}
+        ]
+      ]
     , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
     }
   }
 , "default-ENV":
-  { "imports": {"provider_list": ["./", "..", "field_provider_list"]}
+  { "vars": ["defaults-transition"]
+  , "imports": {"provider_list": ["./", "..", "field_provider_list"]}
   , "expression":
     { "type": "let*"
     , "bindings":
       [ ["fieldname", "defaults"]
       , ["provider", "ENV"]
+      , [ "transition"
+        , {"type": "var", "name": "defaults-transition", "default": null}
+        ]
       , ["default", {"type": "empty_map"}]
       ]
     , "body": {"type": "CALL_EXPRESSION", "name": "provider_list"}
@@ -84,11 +123,12 @@
   }
 , "compile-deps":
   { "doc": ["Collect compile dependencies (headers) from given target_fields"]
-  , "vars": ["deps-fieldnames", "transition"]
+  , "vars": ["deps-fieldnames", "deps-transition"]
   , "vars_doc":
     { "deps-fieldnames":
       ["List of target_field names to collect dependencies from."]
-    , "transition": ["The optional configuration transition for the targets."]
+    , "deps-transition":
+      ["The optional configuration transition for the targets."]
     }
   , "imports":
     { "runfiles_list": ["./", "..", "field_runfiles_list"]
@@ -108,6 +148,7 @@
             { "type": "let*"
             , "bindings":
               [ ["provider", "compile-deps"]
+              , ["transition", {"type": "var", "name": "deps-transition"}]
               , ["default", {"type": "empty_map"}]
               ]
             , "body":
@@ -120,13 +161,41 @@
       }
     }
   }
+, "compile-args-deps":
+  { "doc": ["Collect compile arguments from given target_fields"]
+  , "vars": ["deps-fieldnames", "deps-transition"]
+  , "vars_doc":
+    { "deps-fieldnames":
+      ["List of target_field names to collect arguments from."]
+    , "deps-transition":
+      ["The optional configuration transition for the targets."]
+    }
+  , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
+  , "expression":
+    { "type": "++"
+    , "$1":
+      { "type": "foreach"
+      , "var": "fieldname"
+      , "range": {"type": "var", "name": "deps-fieldnames"}
+      , "body":
+        { "type": "let*"
+        , "bindings":
+          [ ["provider", "compile-args"]
+          , ["transition", {"type": "var", "name": "deps-transition"}]
+          ]
+        , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
+        }
+      }
+    }
+  }
 , "link-deps":
   { "doc": ["Collect link dependencies (libraries) from given target_fields"]
-  , "vars": ["deps-fieldnames", "transition"]
+  , "vars": ["deps-fieldnames", "deps-transition"]
   , "vars_doc":
     { "deps-fieldnames":
       ["List of target_field names to collect dependencies from."]
-    , "transition": ["The optional configuration transition for the targets."]
+    , "deps-transition":
+      ["The optional configuration transition for the targets."]
     }
   , "imports":
     { "artifacts_list": ["./", "..", "field_artifacts_list"]
@@ -145,7 +214,10 @@
           , "$1":
             { "type": "let*"
             , "bindings":
-              [["provider", "link-deps"], ["default", {"type": "empty_map"}]]
+              [ ["provider", "link-deps"]
+              , ["default", {"type": "empty_map"}]
+              , ["transition", {"type": "var", "name": "deps-transition"}]
+              ]
             , "body":
               [ {"type": "CALL_EXPRESSION", "name": "provider_list"}
               , {"type": "CALL_EXPRESSION", "name": "artifacts_list"}
@@ -158,11 +230,12 @@
   }
 , "link-args-deps":
   { "doc": ["Collect linker arguments from given target_fields"]
-  , "vars": ["deps-fieldnames", "transition"]
+  , "vars": ["deps-fieldnames", "deps-transition"]
   , "vars_doc":
     { "deps-fieldnames":
       ["List of target_field names to collect arguments from."]
-    , "transition": ["The optional configuration transition for the targets."]
+    , "deps-transition":
+      ["The optional configuration transition for the targets."]
     }
   , "imports": {"list_provider": ["./", "..", "field_list_provider"]}
   , "expression":
@@ -173,14 +246,25 @@
       , "range": {"type": "var", "name": "deps-fieldnames"}
       , "body":
         { "type": "let*"
-        , "bindings": [["provider", "link-args"]]
+        , "bindings":
+          [ ["provider", "link-args"]
+          , ["transition", {"type": "var", "name": "deps-transition"}]
+          ]
         , "body": {"type": "CALL_EXPRESSION", "name": "list_provider"}
         }
       }
     }
   }
 , "objects":
-  { "vars": ["CXX", "CXXFLAGS", "ENV", "srcs", "compile-deps", "local hdrs"]
+  { "vars":
+    [ "COMPILER"
+    , "COMPILE_FLAGS"
+    , "ENV"
+    , "srcs"
+    , "hdrs"
+    , "private-hdrs"
+    , "compile-deps"
+    ]
   , "expression":
     { "type": "let*"
     , "bindings":
@@ -197,7 +281,13 @@
             [ {"type": "var", "name": "include tree"}
             , { "type": "to_subdir"
               , "subdir": "work"
-              , "$1": {"type": "var", "name": "local hdrs"}
+              , "$1":
+                { "type": "disjoint_map_union"
+                , "$1":
+                  [ {"type": "var", "name": "hdrs"}
+                  , {"type": "var", "name": "private-hdrs"}
+                  ]
+                }
               }
             ]
           }
@@ -254,8 +344,8 @@
                 , "cmd":
                   { "type": "++"
                   , "$1":
-                    [ [{"type": "var", "name": "CXX"}]
-                    , {"type": "var", "name": "CXXFLAGS"}
+                    [ [{"type": "var", "name": "COMPILER"}]
+                    , {"type": "var", "name": "COMPILE_FLAGS"}
                     , ["-I", "work", "-isystem", "include"]
                     , ["-c", {"type": "var", "name": "work src_name"}]
                     , ["-o", {"type": "var", "name": "work out"}]
@@ -284,70 +374,98 @@
       }
     }
   }
+, "compiler-cc":
+  { "vars": ["CC", "defaults-transition"]
+  , "imports": {"default-CC": "default-CC"}
+  , "expression":
+    { "type": "var"
+    , "name": "CC"
+    , "default": {"type": "CALL_EXPRESSION", "name": "default-CC"}
+    }
+  }
+, "compiler-cxx":
+  { "vars": ["CXX", "defaults-transition"]
+  , "imports": {"default-CXX": "default-CXX"}
+  , "expression":
+    { "type": "var"
+    , "name": "CXX"
+    , "default": {"type": "CALL_EXPRESSION", "name": "default-CXX"}
+    }
+  }
 , "compiler":
-  { "vars": ["CC", "CXX"]
-  , "imports": {"default-CC": "default-CC", "default-CXX": "default-CXX"}
+  { "vars": ["CC", "CXX", "pure C", "defaults-transition"]
+  , "imports": {"compiler-cc": "compiler-cc", "compiler-cxx": "compiler-cxx"}
   , "expression":
     { "type": "if"
-    , "cond": {"type": "FIELD", "name": "pure C"}
-    , "then":
-      { "type": "var"
-      , "name": "CC"
-      , "default": {"type": "CALL_EXPRESSION", "name": "default-CC"}
-      }
-    , "else":
-      { "type": "var"
-      , "name": "CXX"
-      , "default": {"type": "CALL_EXPRESSION", "name": "default-CXX"}
-      }
+    , "cond": {"type": "var", "name": "pure C"}
+    , "then": {"type": "CALL_EXPRESSION", "name": "compiler-cc"}
+    , "else": {"type": "CALL_EXPRESSION", "name": "compiler-cxx"}
     }
   }
-, "flags":
-  { "vars": ["CFLAGS", "CXXFLAGS", "ADD_CFLAGS", "ADD_CXXFLAGS"]
-  , "imports":
-    { "default-CFLAGS": "default-CFLAGS"
-    , "default-CXXFLAGS": "default-CXXFLAGS"
+, "flags-cc":
+  { "vars": ["CFLAGS", "ADD_CFLAGS", "defaults-transition"]
+  , "imports": {"default-CFLAGS": "default-CFLAGS"}
+  , "expression":
+    { "type": "++"
+    , "$1":
+      [ { "type": "var"
+        , "name": "CFLAGS"
+        , "default": {"type": "CALL_EXPRESSION", "name": "default-CFLAGS"}
+        }
+      , {"type": "var", "name": "ADD_CFLAGS", "default": []}
+      ]
     }
+  }
+, "flags-cxx":
+  { "vars": ["CXXFLAGS", "ADD_CXXFLAGS", "defaults-transition"]
+  , "imports": {"default-CXXFLAGS": "default-CXXFLAGS"}
   , "expression":
-    { "type": "if"
-    , "cond": {"type": "FIELD", "name": "pure C"}
-    , "then":
-      { "type": "++"
-      , "$1":
-        [ { "type": "var"
-          , "name": "CFLAGS"
-          , "default": {"type": "CALL_EXPRESSION", "name": "default-CFLAGS"}
-          }
-        , {"type": "var", "name": "ADD_CFLAGS", "default": []}
-        ]
-      }
-    , "else":
-      { "type": "++"
-      , "$1":
-        [ { "type": "var"
-          , "name": "CXXFLAGS"
-          , "default": {"type": "CALL_EXPRESSION", "name": "default-CXXFLAGS"}
-          }
-        , {"type": "var", "name": "ADD_CXXFLAGS", "default": []}
-        ]
-      }
+    { "type": "++"
+    , "$1":
+      [ { "type": "var"
+        , "name": "CXXFLAGS"
+        , "default": {"type": "CALL_EXPRESSION", "name": "default-CXXFLAGS"}
+        }
+      , {"type": "var", "name": "ADD_CXXFLAGS", "default": []}
+      ]
     }
   }
-, "lib artifact":
+, "flags":
   { "vars":
-    [ "CXX"
+    [ "CFLAGS"
     , "CXXFLAGS"
+    , "ADD_CFLAGS"
     , "ADD_CXXFLAGS"
-    , "CC"
+    , "pure C"
+    , "defaults-transition"
+    ]
+  , "imports": {"flags-cc": "flags-cc", "flags-cxx": "flags-cxx"}
+  , "expression":
+    { "type": "if"
+    , "cond": {"type": "var", "name": "pure C"}
+    , "then": {"type": "CALL_EXPRESSION", "name": "flags-cc"}
+    , "else": {"type": "CALL_EXPRESSION", "name": "flags-cxx"}
+    }
+  }
+, "lib artifact":
+  { "vars":
+    [ "CC"
+    , "CXX"
     , "CFLAGS"
+    , "CXXFLAGS"
     , "ADD_CFLAGS"
-    , "ENV"
+    , "ADD_CXXFLAGS"
     , "AR"
+    , "ENV"
+    , "name"
+    , "pure C"
     , "srcs"
     , "hdrs"
     , "private-hdrs"
-    , "local cflags"
+    , "stage"
     , "compile-deps"
+    , "compile-args"
+    , "defaults-transition"
     ]
   , "imports":
     { "compiler": "compiler"
@@ -359,28 +477,21 @@
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ [ "stage"
-        , { "type": "join"
-          , "separator": "/"
-          , "$1": {"type": "FIELD", "name": "stage"}
+      [ ["COMPILER", {"type": "CALL_EXPRESSION", "name": "compiler"}]
+      , [ "COMPILE_FLAGS"
+        , { "type": "++"
+          , "$1":
+            [ {"type": "CALL_EXPRESSION", "name": "flags"}
+            , {"type": "var", "name": "compile-args"}
+            ]
           }
         ]
-      , ["CXX", {"type": "CALL_EXPRESSION", "name": "compiler"}]
-      , ["CXXFLAGS", {"type": "CALL_EXPRESSION", "name": "flags"}]
       , [ "AR"
         , { "type": "var"
           , "name": "AR"
           , "default": {"type": "CALL_EXPRESSION", "name": "default-AR"}
           }
         ]
-      , [ "CXXFLAGS"
-        , { "type": "++"
-          , "$1":
-            [ {"type": "var", "name": "CXXFLAGS"}
-            , {"type": "var", "name": "local cflags", "default": []}
-            ]
-          }
-        ]
       , [ "ENV"
         , { "type": "map_union"
           , "$1":
@@ -396,32 +507,16 @@
             }
           }
         ]
-      , [ "local hdrs"
-        , { "type": "disjoint_map_union"
-          , "$1":
-            [ {"type": "var", "name": "hdrs"}
-            , {"type": "var", "name": "private-hdrs"}
-            ]
-          }
-        ]
       , ["objects", {"type": "CALL_EXPRESSION", "name": "objects"}]
       , [ "base name"
-        , { "type": "let*"
-          , "bindings":
-            [ [ "name"
-              , {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
-              ]
-            ]
-          , "body":
-            { "type": "if"
-            , "cond": {"type": "var", "name": "objects"}
-            , "then":
-              { "type": "assert_non_empty"
-              , "msg": "A name has to be provided for non-header-only libraries"
-              , "$1": {"type": "var", "name": "name"}
-              }
-            , "else": {"type": "var", "name": "name"}
+        , { "type": "if"
+          , "cond": {"type": "var", "name": "objects"}
+          , "then":
+            { "type": "assert_non_empty"
+            , "msg": "A name has to be provided for non-header-only libraries"
+            , "$1": {"type": "var", "name": "name"}
             }
+          , "else": {"type": "var", "name": "name"}
           }
         ]
       , [ "libname"
@@ -462,23 +557,30 @@
   }
 , "lib result":
   { "vars":
-    [ "CXX"
-    , "CXXFLAGS"
-    , "ADD_CXXFLAGS"
-    , "CC"
+    [ "CC"
+    , "CXX"
     , "CFLAGS"
+    , "CXXFLAGS"
     , "ADD_CFLAGS"
-    , "ENV"
+    , "ADD_CXXFLAGS"
     , "AR"
+    , "ENV"
+    , "name"
+    , "pure C"
     , "srcs"
     , "hdrs"
     , "private-hdrs"
-    , "local cflags"
-    , "link external"
+    , "cflags"
+    , "private-cflags"
+    , "private-ldflags"
+    , "stage"
     , "extra-provides"
+    , "public-fieldnames"
+    , "private-fieldnames"
     ]
   , "imports":
     { "compile-deps": "compile-deps"
+    , "compile-args-deps": "compile-args-deps"
     , "link-deps": "link-deps"
     , "link-args-deps": "link-args-deps"
     , "lib artifact": "lib artifact"
@@ -486,8 +588,20 @@
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ ["deps-fieldnames", ["deps", "private-deps", "proto-deps"]]
+      [ ["deps-fieldnames", {"type": "var", "name": "private-fieldnames"}]
       , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
+      , [ "compile-args"
+        , { "type": "nub_right"
+          , "$1":
+            { "type": "++"
+            , "$1":
+              [ {"type": "var", "name": "cflags"}
+              , {"type": "var", "name": "private-cflags"}
+              , {"type": "CALL_EXPRESSION", "name": "compile-args-deps"}
+              ]
+            }
+          }
+        ]
       , ["link-deps", {"type": "CALL_EXPRESSION", "name": "link-deps"}]
       , ["lib", {"type": "CALL_EXPRESSION", "name": "lib artifact"}]
       , [ "link-args"
@@ -496,14 +610,25 @@
             { "type": "++"
             , "$1":
               [ {"type": "keys", "$1": {"type": "var", "name": "lib"}}
-              , {"type": "var", "name": "link external", "default": []}
+              , {"type": "var", "name": "private-ldflags", "default": []}
               , {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
               ]
             }
           }
         ]
-      , ["deps-fieldnames", ["deps", "proto-deps"]]
+      , ["deps-fieldnames", {"type": "var", "name": "public-fieldnames"}]
       , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
+      , [ "compile-args"
+        , { "type": "nub_right"
+          , "$1":
+            { "type": "++"
+            , "$1":
+              [ {"type": "var", "name": "cflags"}
+              , {"type": "CALL_EXPRESSION", "name": "compile-args-deps"}
+              ]
+            }
+          }
+        ]
       ]
     , "body":
       { "type": "RESULT"
@@ -512,7 +637,10 @@
       , "provides":
         { "type": "map_union"
         , "$1":
-          [ {"type": "env", "vars": ["compile-deps", "link-deps", "link-args"]}
+          [ { "type": "env"
+            , "vars":
+              ["compile-deps", "compile-args", "link-deps", "link-args"]
+            }
           , { "type": "var"
             , "name": "extra-provides"
             , "default": {"type": "empty_map"}
@@ -522,4 +650,171 @@
       }
     }
   }
+, "bin artifact":
+  { "doc": ["Produces the binary artifact."]
+  , "vars":
+    [ "CC"
+    , "CXX"
+    , "CFLAGS"
+    , "CXXFLAGS"
+    , "ADD_CFLAGS"
+    , "ADD_CXXFLAGS"
+    , "ENV"
+    , "name"
+    , "pure C"
+    , "srcs"
+    , "private-hdrs"
+    , "stage"
+    , "compile-deps"
+    , "compile-args"
+    , "link-deps"
+    , "link-args"
+    , "defaults-transition"
+    ]
+  , "imports":
+    { "compiler": "compiler"
+    , "flags": "flags"
+    , "objects": "objects"
+    , "default-ENV": "default-ENV"
+    }
+  , "expression":
+    { "type": "let*"
+    , "bindings":
+      [ ["COMPILER", {"type": "CALL_EXPRESSION", "name": "compiler"}]
+      , [ "COMPILE_FLAGS"
+        , { "type": "++"
+          , "$1":
+            [ {"type": "CALL_EXPRESSION", "name": "flags"}
+            , {"type": "var", "name": "compile-args"}
+            ]
+          }
+        ]
+      , [ "ENV"
+        , { "type": "map_union"
+          , "$1":
+            { "type": "++"
+            , "$1":
+              [ {"type": "CALL_EXPRESSION", "name": "default-ENV"}
+              , [ { "type": "var"
+                  , "name": "ENV"
+                  , "default": {"type": "empty_map"}
+                  }
+                ]
+              ]
+            }
+          }
+        ]
+      , ["hdrs", {"type": "empty_map"}]
+      , ["objects", {"type": "CALL_EXPRESSION", "name": "objects"}]
+      , [ "link-args"
+        , { "type": "nub_right"
+          , "$1":
+            { "type": "++"
+            , "$1":
+              [ {"type": "keys", "$1": {"type": "var", "name": "objects"}}
+              , {"type": "var", "name": "link-args"}
+              ]
+            }
+          }
+        ]
+      , [ "binpath"
+        , { "type": "if"
+          , "cond": {"type": "var", "name": "stage"}
+          , "then":
+            { "type": "join"
+            , "separator": "/"
+            , "$1":
+              [ {"type": "var", "name": "stage"}
+              , {"type": "var", "name": "name"}
+              ]
+            }
+          , "else": {"type": "var", "name": "name"}
+          }
+        ]
+      , [ "binary"
+        , { "type": "ACTION"
+          , "outs": [{"type": "var", "name": "binpath"}]
+          , "inputs":
+            { "type": "disjoint_map_union"
+            , "$1":
+              [ {"type": "var", "name": "objects"}
+              , {"type": "var", "name": "link-deps"}
+              ]
+            }
+          , "cmd":
+            { "type": "++"
+            , "$1":
+              [ [ {"type": "var", "name": "COMPILER"}
+                , "-o"
+                , {"type": "var", "name": "binpath"}
+                ]
+              , {"type": "var", "name": "COMPILE_FLAGS"}
+              , {"type": "var", "name": "link-args"}
+              ]
+            }
+          , "env": {"type": "var", "name": "ENV"}
+          }
+        ]
+      ]
+    , "body": {"type": "var", "name": "binary"}
+    }
+  }
+, "bin result":
+  { "doc": ["Produces the binary target result."]
+  , "vars":
+    [ "CC"
+    , "CXX"
+    , "CFLAGS"
+    , "CXXFLAGS"
+    , "ADD_CFLAGS"
+    , "ADD_CXXFLAGS"
+    , "ENV"
+    , "name"
+    , "pure C"
+    , "srcs"
+    , "private-hdrs"
+    , "private-cflags"
+    , "private-ldflags"
+    , "stage"
+    , "private-fieldnames"
+    ]
+  , "imports":
+    { "compile-deps": "compile-deps"
+    , "compile-args-deps": "compile-args-deps"
+    , "link-deps": "link-deps"
+    , "link-args-deps": "link-args-deps"
+    , "binary": "bin artifact"
+    }
+  , "expression":
+    { "type": "let*"
+    , "bindings":
+      [ ["deps-fieldnames", {"type": "var", "name": "private-fieldnames"}]
+      , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
+      , [ "compile-args"
+        , { "type": "++"
+          , "$1":
+            [ {"type": "CALL_EXPRESSION", "name": "compile-args-deps"}
+            , {"type": "var", "name": "private-cflags"}
+            ]
+          }
+        ]
+      , ["link-deps", {"type": "CALL_EXPRESSION", "name": "link-deps"}]
+      , [ "link-args"
+        , { "type": "nub_right"
+          , "$1":
+            { "type": "++"
+            , "$1":
+              [ {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
+              , {"type": "var", "name": "private-ldflags"}
+              ]
+            }
+          }
+        ]
+      ]
+    , "body":
+      { "type": "RESULT"
+      , "artifacts": {"type": "CALL_EXPRESSION", "name": "binary"}
+      }
+    }
+  }
 }
diff --git a/rules/CC/RULES b/rules/CC/RULES
index 9e599e19..9b041dd4 100644
--- a/rules/CC/RULES
+++ b/rules/CC/RULES
@@ -1,7 +1,7 @@
 { "defaults":
   { "doc":
     [ "A rule to provide defaults."
-    , "All CC targets take their defaults for CXX, CC, flags, etc from"
+    , "All CC targets take their defaults for CC, CXX, flags, etc from"
     , "the target [\"CC\", \"defaults\"]. This is probably the only sensibe"
     , "use of this rule. As targets form a different root, the defaults"
     , "can be provided without changing this directory."
@@ -14,8 +14,8 @@
     , "CXXFLAGS"
     , "ADD_CFLAGS"
     , "ADD_CXXFLAGS"
-    , "PATH"
     , "AR"
+    , "PATH"
     ]
   , "imports": {"base-provides": "defaults-base-provides"}
   , "expression":
@@ -110,26 +110,28 @@
     }
   }
 , "library":
-  { "doc": ["A C++ libaray"]
+  { "doc": ["A C++ library"]
   , "target_fields":
     ["srcs", "hdrs", "private-hdrs", "deps", "private-deps", "proto"]
   , "string_fields":
     [ "name"
     , "stage"
     , "pure C"
-    , "local defines"
-    , "local cflags"
-    , "link external"
+    , "defines"
+    , "private-defines"
+    , "cflags"
+    , "private-cflags"
+    , "private-ldflags"
     ]
   , "config_vars":
-    [ "CXX"
-    , "CC"
-    , "CXXFLAGS"
+    [ "CC"
+    , "CXX"
     , "CFLAGS"
-    , "ADD_CXXFLAGS"
+    , "CXXFLAGS"
     , "ADD_CFLAGS"
-    , "ENV"
+    , "ADD_CXXFLAGS"
     , "AR"
+    , "ENV"
     ]
   , "implicit": {"defaults": ["defaults"]}
   , "field_doc":
@@ -151,13 +153,19 @@
       , "In particular, CC is used to compile rather than CXX (or their"
       , "respective defaults)."
       ]
-    , "local defines":
+    , "defines":
+      [ "List of defines set for this target and its consumers."
+      , "Each list entry will be prepended by \"-D\"."
+      ]
+    , "private-defines":
       [ "List of defines set for source files local to this target."
       , "Each list entry will be prepended by \"-D\"."
       ]
-    , "local cflags":
+    , "cflags":
+      ["List of compile flags set for this target and its consumers."]
+    , "private-cflags":
       ["List of compile flags set for source files local to this target."]
-    , "link external":
+    , "private-ldflags":
       [ "Additional linker flags for linking external libraries (not built"
       , "by this tool, typically system libraries)."
       ]
@@ -175,30 +183,31 @@
       ]
     }
   , "config_doc":
-    { "CXX":
-      [ "The name of the C++ compiler to be used."
-      , "If None, the respective value from [\"CC\", \"defaults\"] will be taken."
-      ]
-    , "CC":
+    { "CC":
       [ "The name of the C compiler to be used (when compiling pure C code)."
       , "If None, the respective value from [\"CC\", \"defaults\"] will be taken."
       ]
-    , "AR":
-      [ "The archive tool to used for creating the library"
+    , "CXX":
+      [ "The name of the C++ compiler to be used."
       , "If None, the respective value from [\"CC\", \"defaults\"] will be taken."
       ]
-    , "ENV": ["The environment for any action generated."]
+    , "CFLAGS":
+      [ "The flags for CC to be used instead of the default ones."
+      , "For libraries that should be built in a non-standard way; usually"
+      , "adapting the default target [\"CC\", \"defaults\"] is the better"
+      , "choice."
+      ]
     , "CXXFLAGS":
       [ "The flags for CXX to be used instead of the default ones."
       , "For libraries that should be built in a non-standard way; usually"
       , "adapting the default target [\"CC\", \"defaults\"] is the better"
       , "choice."
       ]
-    , "CFLAGS":
-      [ "The flags for CC to be used instead of the default ones."
+    , "ADD_CFLAGS":
+      [ "The flags to add to the default ones for CC."
       , "For libraries that should be built in a non-standard way; usually"
       , "adapting the default target [\"CC\", \"defaults\"] is the better"
-      , "choice"
+      , "choice."
       ]
     , "ADD_CXXFLAGS":
       [ "The flags to add to the default ones for CXX."
@@ -206,12 +215,11 @@
       , "adapting the default target [\"CC\", \"defaults\"] is the better"
       , "choice."
       ]
-    , "ADD_CFLAGS":
-      [ "The flags to add to the default ones for CC."
-      , "For libraries that should be built in a non-standard way; usually"
-      , "adapting the default target [\"CC\", \"defaults\"] is the better"
-      , "choice."
+    , "AR":
+      [ "The archive tool to used for creating the library"
+      , "If None, the respective value from [\"CC\", \"defaults\"] will be taken."
       ]
+    , "ENV": ["The environment for any action generated."]
     }
   , "artifacts_doc":
     ["The actual library (libname.a) staged in the specified directory"]
@@ -241,44 +249,35 @@
       }
     }
   , "imports":
-    { "artifacts": ["./", "..", "field_artifacts"]
-    , "default-CXXFLAGS": "default-CXXFLAGS"
-    , "default-CFLAGS": "default-CFLAGS"
-    , "result": "lib result"
-    }
+    {"artifacts": ["./", "..", "field_artifacts"], "result": "lib result"}
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ [ "local defines"
-        , { "type": "foreach"
-          , "var": "def"
-          , "range": {"type": "FIELD", "name": "local defines"}
-          , "body":
-            {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
-          }
-        ]
-      , ["local cflags", {"type": "FIELD", "name": "local cflags"}]
-      , [ "CFLAGS"
+      [ ["name", {"type": "join", "$1": {"type": "FIELD", "name": "name"}}]
+      , ["pure C", {"type": "FIELD", "name": "pure C"}]
+      , [ "cflags"
         , { "type": "++"
           , "$1":
-            [ { "type": "var"
-              , "name": "CFLAGS"
-              , "default":
-                {"type": "CALL_EXPRESSION", "name": "default-CFLAGS"}
+            [ {"type": "FIELD", "name": "cflags"}
+            , { "type": "foreach"
+              , "var": "def"
+              , "range": {"type": "FIELD", "name": "defines"}
+              , "body":
+                {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
               }
-            , {"type": "var", "name": "local defines"}
             ]
           }
         ]
-      , [ "CXXFLAGS"
+      , [ "private-cflags"
         , { "type": "++"
           , "$1":
-            [ { "type": "var"
-              , "name": "CXXFLAGS"
-              , "default":
-                {"type": "CALL_EXPRESSION", "name": "default-CXXFLAGS"}
+            [ { "type": "foreach"
+              , "var": "def"
+              , "range": {"type": "FIELD", "name": "private-defines"}
+              , "body":
+                {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
               }
-            , {"type": "var", "name": "local defines"}
+            , {"type": "FIELD", "name": "private-cflags"}
             ]
           }
         ]
@@ -318,18 +317,26 @@
             }
           }
         ]
-      , ["link external", {"type": "FIELD", "name": "link external"}]
+      , ["private-ldflags", {"type": "FIELD", "name": "private-ldflags"}]
+      , ["public-fieldnames", ["deps", "proto-deps"]]
+      , ["private-fieldnames", ["deps", "private-deps", "proto-deps"]]
       ]
     , "body": {"type": "CALL_EXPRESSION", "name": "result"}
     }
   }
 , "binary":
   { "doc": ["A binary written in C++"]
-  , "target_fields": ["srcs", "private-hdrs", "deps", "proto"]
+  , "target_fields": ["srcs", "private-hdrs", "private-deps", "private-proto"]
   , "string_fields":
-    ["name", "stage", "pure C", "local defines", "link external"]
+    [ "name"
+    , "stage"
+    , "pure C"
+    , "private-defines"
+    , "private-cflags"
+    , "private-ldflags"
+    ]
   , "config_vars":
-    ["CXX", "CC", "CXXFLAGS", "CFLAGS", "ADD_CXXFLAGS", "ADD_CFLAGS", "ENV"]
+    ["CC", "CXX", "CFLAGS", "CXXFLAGS", "ADD_CFLAGS", "ADD_CXXFLAGS", "ENV"]
   , "implicit": {"defaults": ["defaults"]}
   , "field_doc":
     { "name": ["The name of the binary"]
@@ -347,14 +354,16 @@
       [ "If non-empty, compile as C sources rathter than C++ sources."
       , "In particular, CC is used to compile rather than CXX"
       ]
-    , "local defines":
+    , "private-defines":
       [ "List of defines set for source files local to this target."
       , "Each list entry will be prepended by \"-D\"."
       ]
-    , "link external":
+    , "private-cflags":
+      ["List of compile flags set for source files local to this target."]
+    , "private-ldflags":
       ["Additional linker flags for linking external libraries."]
-    , "deps": ["Any other libraries this binary depends upon."]
-    , "proto":
+    , "private-deps": ["Any other libraries this binary depends upon."]
+    , "private-proto":
       [ "Any [\"proto\", \"library\"] this target depends upon directly."
       , "The creation of C++ bindings for this proto library as well as of"
       , "is dependencies will be taken care of (as anonymous targets, so no"
@@ -363,32 +372,32 @@
       ]
     }
   , "config_doc":
-    { "CXX": ["The name of the C++ compiler to be used."]
-    , "CC":
+    { "CC":
       ["The name of the C compiler to be used (when compiling pure C code)"]
-    , "ENV": ["The environment for any action generated."]
-    , "CXXFLAGS":
-      [ "The flags for CXX to be used instead of the default ones"
-      , "taken from the [\"CC\", \"defaults\"] target"
-      ]
+    , "CXX": ["The name of the C++ compiler to be used."]
     , "CFLAGS":
       [ "The flags for CXX to be used instead of the default ones"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
-    , "ADD_CXXFLAGS":
-      [ "The flags to add to the default ones for CXX"
+    , "CXXFLAGS":
+      [ "The flags for CXX to be used instead of the default ones"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
     , "ADD_CFLAGS":
       [ "The flags to add to the default ones for CC"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
+    , "ADD_CXXFLAGS":
+      [ "The flags to add to the default ones for CXX"
+      , "taken from the [\"CC\", \"defaults\"] target"
+      ]
+    , "ENV": ["The environment for any action generated."]
     }
   , "artifacts_doc": ["The final binary, staged to the given directory"]
   , "runfiles_doc": ["None"]
   , "anonymous":
-    { "proto-deps":
-      { "target": "proto"
+    { "private-proto-deps":
+      { "target": "private-proto"
       , "provider": "proto"
       , "rule_map":
         { "library": ["./", "proto", "library"]
@@ -397,26 +406,17 @@
       }
     }
   , "imports":
-    { "artifacts": ["./", "..", "field_artifacts"]
-    , "compile-deps": "compile-deps"
-    , "link-deps": "link-deps"
-    , "link-args-deps": "link-args-deps"
-    , "objects": "objects"
-    , "compiler": "compiler"
-    , "flags": "flags"
-    , "default-ENV": "default-ENV"
-    }
+    {"artifacts": ["./", "..", "field_artifacts"], "bin result": "bin result"}
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ [ "local defines"
-        , { "type": "foreach"
-          , "var": "def"
-          , "range": {"type": "FIELD", "name": "local defines"}
-          , "body":
-            {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
+      [ [ "name"
+        , { "type": "assert_non_empty"
+          , "msg": "A non-empty name has to be provided for binaries"
+          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
           }
         ]
+      , ["pure C", {"type": "FIELD", "name": "pure C"}]
       , [ "stage"
         , { "type": "join"
           , "separator": "/"
@@ -433,7 +433,7 @@
             }
           }
         ]
-      , [ "local hdrs"
+      , [ "private-hdrs"
         , { "type": "to_subdir"
           , "subdir": {"type": "var", "name": "stage"}
           , "$1":
@@ -443,94 +443,23 @@
             }
           }
         ]
-      , ["CXX", {"type": "CALL_EXPRESSION", "name": "compiler"}]
-      , ["CXXFLAGS", {"type": "CALL_EXPRESSION", "name": "flags"}]
-      , [ "CXXFLAGS"
+      , [ "private-cflags"
         , { "type": "++"
           , "$1":
-            [ {"type": "var", "name": "CXXFLAGS"}
-            , {"type": "var", "name": "local defines"}
+            [ { "type": "foreach"
+              , "var": "def"
+              , "range": {"type": "FIELD", "name": "private-defines"}
+              , "body":
+                {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
+              }
+            , {"type": "FIELD", "name": "private-cflags"}
             ]
           }
         ]
-      , [ "ENV"
-        , { "type": "map_union"
-          , "$1":
-            { "type": "++"
-            , "$1":
-              [ {"type": "CALL_EXPRESSION", "name": "default-ENV"}
-              , [ { "type": "var"
-                  , "name": "ENV"
-                  , "default": {"type": "empty_map"}
-                  }
-                ]
-              ]
-            }
-          }
-        ]
-      , ["deps-fieldnames", ["deps", "proto-deps"]]
-      , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
-      , ["link-deps", {"type": "CALL_EXPRESSION", "name": "link-deps"}]
-      , ["objects", {"type": "CALL_EXPRESSION", "name": "objects"}]
-      , [ "base name"
-        , { "type": "assert_non_empty"
-          , "msg": "A non-empty name has to be provided for binaries"
-          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
-          }
-        ]
-      , [ "binary name"
-        , { "type": "if"
-          , "cond": {"type": "var", "name": "stage"}
-          , "else": {"type": "var", "name": "base name"}
-          , "then":
-            { "type": "join"
-            , "separator": "/"
-            , "$1":
-              [ {"type": "var", "name": "stage"}
-              , {"type": "var", "name": "base name"}
-              ]
-            }
-          }
-        ]
-      , [ "link-args"
-        , { "type": "nub_right"
-          , "$1":
-            { "type": "++"
-            , "$1":
-              [ {"type": "keys", "$1": {"type": "var", "name": "objects"}}
-              , {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
-              , {"type": "FIELD", "name": "link external"}
-              ]
-            }
-          }
-        ]
-      , [ "binary"
-        , { "type": "ACTION"
-          , "outs": [{"type": "var", "name": "binary name"}]
-          , "inputs":
-            { "type": "disjoint_map_union"
-            , "$1":
-              [ {"type": "var", "name": "objects"}
-              , {"type": "var", "name": "link-deps"}
-              ]
-            }
-          , "cmd":
-            { "type": "++"
-            , "$1":
-              [ [ {"type": "var", "name": "CXX"}
-                , "-o"
-                , {"type": "var", "name": "binary name"}
-                ]
-              , {"type": "var", "name": "CXXFLAGS"}
-              , {"type": "var", "name": "link-args"}
-              ]
-            }
-          , "env": {"type": "var", "name": "ENV"}
-          }
-        ]
+      , ["private-ldflags", {"type": "FIELD", "name": "private-ldflags"}]
+      , ["private-fieldnames", ["private-deps", "private-proto-deps"]]
       ]
-    , "body":
-      {"type": "RESULT", "artifacts": {"type": "var", "name": "binary"}}
+    , "body": {"type": "CALL_EXPRESSION", "name": "bin result"}
     }
   }
 }
diff --git a/rules/CC/auto/RULES b/rules/CC/auto/RULES
index ab1e689f..24296344 100644
--- a/rules/CC/auto/RULES
+++ b/rules/CC/auto/RULES
@@ -24,12 +24,12 @@
       ]
     }
   , "config_doc":
-    { "CXX":
-      [ "The name of the C++ compiler to be used by checks. If None, the"
+    { "CC":
+      [ "The name of the C compiler to be used by checks. If None, the"
       , "respective value from [\"CC\", \"defaults\"] will be taken."
       ]
-    , "CC":
-      [ "The name of the C compiler to be used by checks. If None, the"
+    , "CXX":
+      [ "The name of the C++ compiler to be used by checks. If None, the"
       , "respective value from [\"CC\", \"defaults\"] will be taken."
       ]
     , "CFLAGS":
diff --git a/rules/CC/proto/EXPRESSIONS b/rules/CC/proto/EXPRESSIONS
index b2b3ea0d..1ab17a59 100644
--- a/rules/CC/proto/EXPRESSIONS
+++ b/rules/CC/proto/EXPRESSIONS
@@ -8,13 +8,17 @@
   }
 , "protoc-compile":
   { "vars":
-    [ "transition"
-    , "service support"
-    , "CXX"
+    [ "CXX"
     , "CXXFLAGS"
     , "ADD_CXXFLAGS"
-    , "ENV"
     , "AR"
+    , "ENV"
+    , "name"
+    , "stage"
+    , "service support"
+    , "deps-transition"
+    , "public-fieldnames"
+    , "private-fieldnames"
     ]
   , "imports":
     { "stage": ["", "stage_singleton_field"]
@@ -26,9 +30,14 @@
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ [ "protoc"
+      [ ["pure C", false]
+      , [ "protoc"
         , { "type": "let*"
-          , "bindings": [["fieldname", "protoc"], ["location", "protoc"]]
+          , "bindings":
+            [ ["fieldname", "protoc"]
+            , ["transition", {"type": "var", "name": "deps-transition"}]
+            , ["location", "protoc"]
+            ]
           , "body": {"type": "CALL_EXPRESSION", "name": "stage"}
           }
         ]
@@ -39,6 +48,7 @@
             { "type": "let*"
             , "bindings":
               [ ["fieldname", "grpc_cpp_plugin"]
+              , ["transition", {"type": "var", "name": "deps-transition"}]
               , ["location", "grpc_cpp_plugin"]
               ]
             , "body": {"type": "CALL_EXPRESSION", "name": "stage"}
@@ -52,8 +62,7 @@
           , "subdir": "work"
           , "$1":
             { "type": "let*"
-            , "bindings":
-              [["fieldname", "well_known_protos"], ["transition", null]]
+            , "bindings": [["fieldname", "well_known_protos"]]
             , "body": {"type": "CALL_EXPRESSION", "name": "artifacts"}
             }
           }
@@ -63,7 +72,7 @@
           , "msg": "Sources may not conflict"
           , "$1":
             { "type": "let*"
-            , "bindings": [["fieldname", "srcs"], ["transition", null]]
+            , "bindings": [["fieldname", "srcs"]]
             , "body": {"type": "CALL_EXPRESSION", "name": "artifacts_list"}
             }
           }
@@ -289,7 +298,9 @@
           , "value": {"type": "var", "name": "all proto srcs"}
           }
         ]
-      , ["local cflags", ["-Wno-sign-conversion", "-Wno-unused-function"]]
+      , ["cflags", []]
+      , ["private-cflags", ["-Wno-sign-conversion", "-Wno-unused-function"]]
+      , ["private-ldflags", []]
       ]
     , "body": {"type": "CALL_EXPRESSION", "name": "result"}
     }
diff --git a/rules/CC/proto/RULES b/rules/CC/proto/RULES
index d53ab35e..d1cfc4e5 100644
--- a/rules/CC/proto/RULES
+++ b/rules/CC/proto/RULES
@@ -8,25 +8,12 @@
   , "string_fields": ["name", "stage"]
   , "target_fields": ["srcs", "deps"]
   , "config_vars":
-    [ "OS"
-    , "ARCH"
-    , "HOST_ARCH"
-    , "CXX"
-    , "CC"
-    , "CXXFLAGS"
-    , "CFLAGS"
-    , "ADD_CXXFLAGS"
-    , "ADD_CFLAGS"
-    , "ENV"
-    , "AR"
-    ]
+    ["OS", "ARCH", "HOST_ARCH", "CXX", "CFLAGS", "ADD_CFLAGS", "AR", "ENV"]
   , "implicit":
     { "protoc": [["@", "protoc", "", "protoc"]]
     , "defaults": [["./", "..", "defaults"]]
     , "proto-deps": [["@", "protoc", "", "C++ runtime"]]
     , "well_known_protos": [["@", "protoc", "", "well_known_protos"]]
-    , "pure C": []
-    , "private-deps": []
     }
   , "imports":
     { "protoc-compile": "protoc-compile"
@@ -37,7 +24,19 @@
   , "expression":
     { "type": "let*"
     , "bindings":
-      [["transition", {"type": "CALL_EXPRESSION", "name": "host transition"}]]
+      [ ["name", {"type": "join", "$1": {"type": "FIELD", "name": "name"}}]
+      , [ "stage"
+        , { "type": "join"
+          , "separator": "/"
+          , "$1": {"type": "FIELD", "name": "stage"}
+          }
+        ]
+      , [ "deps-transition"
+        , {"type": "CALL_EXPRESSION", "name": "host transition"}
+        ]
+      , ["public-fieldnames", ["deps", "proto-deps"]]
+      , ["private-fieldnames", ["deps", "proto-deps"]]
+      ]
     , "body": {"type": "CALL_EXPRESSION", "name": "protoc-compile"}
     }
   }
@@ -51,18 +50,7 @@
   , "string_fields": ["name", "stage"]
   , "target_fields": ["srcs", "deps"]
   , "config_vars":
-    [ "OS"
-    , "ARCH"
-    , "HOST_ARCH"
-    , "CXX"
-    , "CC"
-    , "CXXFLAGS"
-    , "CFLAGS"
-    , "ADD_CXXFLAGS"
-    , "ADD_CFLAGS"
-    , "ENV"
-    , "AR"
-    ]
+    ["OS", "ARCH", "HOST_ARCH", "CXX", "CXXFLAGS", "ADD_CXXFLAGS", "AR", "ENV"]
   , "implicit":
     { "protoc": [["@", "protoc", "", "protoc"]]
     , "grpc_cpp_plugin": [["@", "grpc", "src/compiler", "grpc_cpp_plugin"]]
@@ -72,8 +60,6 @@
       , ["@", "protoc", "", "C++ runtime"]
       ]
     , "well_known_protos": [["@", "protoc", "", "well_known_protos"]]
-    , "pure C": []
-    , "private-deps": []
     }
   , "imports":
     { "protoc-compile": "protoc-compile"
@@ -88,7 +74,18 @@
     { "type": "let*"
     , "bindings":
       [ ["service support", true]
-      , ["transition", {"type": "CALL_EXPRESSION", "name": "host transition"}]
+      , ["name", {"type": "join", "$1": {"type": "FIELD", "name": "name"}}]
+      , [ "stage"
+        , { "type": "join"
+          , "separator": "/"
+          , "$1": {"type": "FIELD", "name": "stage"}
+          }
+        ]
+      , [ "deps-transition"
+        , {"type": "CALL_EXPRESSION", "name": "host transition"}
+        ]
+      , ["public-fieldnames", ["deps", "proto-deps"]]
+      , ["private-fieldnames", ["deps", "proto-deps"]]
       ]
     , "body": {"type": "CALL_EXPRESSION", "name": "protoc-compile"}
     }
diff --git a/rules/CC/test/RULES b/rules/CC/test/RULES
index 0d7a9ba7..b42b6c4f 100644
--- a/rules/CC/test/RULES
+++ b/rules/CC/test/RULES
@@ -4,24 +4,28 @@
     , "FIXME: the test binary and data must be built for host"
     ]
   , "tainted": ["test"]
-  , "target_fields": ["srcs", "private-hdrs", "deps", "data"]
-  , "string_fields": ["name", "stage"]
+  , "target_fields": ["srcs", "private-hdrs", "private-deps", "data"]
+  , "string_fields":
+    [ "name"
+    , "stage"
+    , "pure C"
+    , "private-defines"
+    , "private-cflags"
+    , "private-ldflags"
+    ]
   , "config_vars":
-    [ "CXX"
-    , "CC"
-    , "CXXFLAGS"
+    [ "CC"
+    , "CXX"
     , "CFLAGS"
-    , "ADD_CXXFLAGS"
+    , "CXXFLAGS"
     , "ADD_CFLAGS"
+    , "ADD_CXXFLAGS"
     , "ENV"
     , "TEST_ENV"
     , "CC_TEST_LAUNCHER"
     ]
   , "implicit":
-    { "defaults": [["./", "..", "defaults"]]
-    , "proto-deps": []
-    , "runner": ["test_runner.sh"]
-    }
+    {"defaults": [["./", "..", "defaults"]], "runner": ["test_runner.sh"]}
   , "field_doc":
     { "name":
       [ "The name of the test"
@@ -33,6 +37,16 @@
       [ "Any additional header files that need to be present when compiling"
       , "the test binary."
       ]
+    , "private-defines":
+      [ "List of defines set for source files local to this target."
+      , "Each list entry will be prepended by \"-D\"."
+      ]
+    , "private-cflags":
+      ["List of compile flags set for source files local to this target."]
+    , "private-ldflags":
+      [ "Additional linker flags for linking external libraries (not built"
+      , "by this tool, typically system libraries)."
+      ]
     , "stage":
       [ "The logical location of all header and source files."
       , "Individual directory components are joined with \"/\"."
@@ -40,25 +54,25 @@
     , "data": ["Any files the test binary needs access to when running"]
     }
   , "config_doc":
-    { "CXX": ["The name of the C++ compiler to be used."]
-    , "CC": ["The name of the C compiler to be used."]
-    , "ENV": ["The environment for any action generated."]
-    , "CXXFLAGS":
-      [ "The flags for CXX to be used instead of the default ones"
-      , "taken from the [\"CC\", \"defaults\"] target"
-      ]
+    { "CC": ["The name of the C compiler to be used."]
+    , "CXX": ["The name of the C++ compiler to be used."]
     , "CFLAGS":
       [ "The flags for CC to be used instead of the default ones"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
-    , "ADD_CXXFLAGS":
-      [ "The flags to add to the default ones for CXX"
+    , "CXXFLAGS":
+      [ "The flags for CXX to be used instead of the default ones"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
     , "ADD_CFLAGS":
       [ "The flags to add to the default ones for CC"
       , "taken from the [\"CC\", \"defaults\"] target"
       ]
+    , "ADD_CXXFLAGS":
+      [ "The flags to add to the default ones for CXX"
+      , "taken from the [\"CC\", \"defaults\"] target"
+      ]
+    , "ENV": ["The environment for any action generated."]
     , "TEST_ENV": ["The environment for executing the test runner."]
     , "CC_TEST_LAUNCHER":
       [ "List of strings representing the launcher that is prepend to the"
@@ -75,24 +89,30 @@
     ]
   , "runfiles_doc":
     [ "A tree consisting of the artifacts staged at the name of the test."
-    , "As the built-in \"install\" rule only takes the runfiles of its \"deps\""
-    , "argument, this gives an easy way of defining test suites."
+    , "As the built-in \"install\" rule only takes the runfiles of its"
+    , "\"private-deps\" argument, this gives an easy way of defining test"
+    , "suites."
     ]
   , "imports":
     { "artifacts": ["./", "../..", "field_artifacts"]
     , "runfiles_list": ["./", "../..", "field_runfiles_list"]
     , "compile-deps": ["./", "..", "compile-deps"]
+    , "compile-args-deps": ["./", "..", "compile-args-deps"]
     , "link-deps": ["./", "..", "link-deps"]
     , "link-args-deps": ["./", "..", "link-args-deps"]
-    , "objects": ["./", "..", "objects"]
-    , "default-CXX": ["./", "..", "default-CXX"]
-    , "default-CXXFLAGS": ["./", "..", "default-CXXFLAGS"]
-    , "default-ENV": ["./", "..", "default-ENV"]
+    , "binary": ["./", "..", "bin artifact"]
     }
   , "expression":
     { "type": "let*"
     , "bindings":
-      [ [ "stage"
+      [ [ "name"
+        , { "type": "assert_non_empty"
+          , "msg": "A non-empty name has to be provided for binaries"
+          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
+          }
+        ]
+      , ["pure C", {"type": "FIELD", "name": "pure C"}]
+      , [ "stage"
         , { "type": "join"
           , "separator": "/"
           , "$1": {"type": "FIELD", "name": "stage"}
@@ -108,7 +128,7 @@
             }
           }
         ]
-      , [ "local hdrs"
+      , [ "private-hdrs"
         , { "type": "to_subdir"
           , "subdir": {"type": "var", "name": "stage"}
           , "$1":
@@ -118,92 +138,32 @@
             }
           }
         ]
-      , [ "CXX"
-        , { "type": "var"
-          , "name": "CXX"
-          , "default": {"type": "CALL_EXPRESSION", "name": "default-CXX"}
-          }
-        ]
-      , [ "CXXFLAGS"
-        , { "type": "var"
-          , "name": "CXXFLAGS"
-          , "default": {"type": "CALL_EXPRESSION", "name": "default-CXXFLAGS"}
-          }
-        ]
-      , [ "ENV"
-        , { "type": "map_union"
+      , ["deps-fieldnames", ["private-deps"]]
+      , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
+      , [ "compile-args"
+        , { "type": "++"
           , "$1":
-            { "type": "++"
-            , "$1":
-              [ {"type": "CALL_EXPRESSION", "name": "default-ENV"}
-              , [ { "type": "var"
-                  , "name": "ENV"
-                  , "default": {"type": "empty_map"}
-                  }
-                ]
-              ]
-            }
+            [ { "type": "foreach"
+              , "var": "def"
+              , "range": {"type": "FIELD", "name": "private-defines"}
+              , "body":
+                {"type": "join", "$1": ["-D", {"type": "var", "name": "def"}]}
+              }
+            , {"type": "FIELD", "name": "private-cflags"}
+            , {"type": "CALL_EXPRESSION", "name": "compile-args-deps"}
+            ]
           }
         ]
-      , ["deps-fieldnames", ["deps", "proto-deps"]]
-      , ["compile-deps", {"type": "CALL_EXPRESSION", "name": "compile-deps"}]
       , ["link-deps", {"type": "CALL_EXPRESSION", "name": "link-deps"}]
-      , ["objects", {"type": "CALL_EXPRESSION", "name": "objects"}]
-      , [ "base name"
-        , { "type": "assert_non_empty"
-          , "msg": "A non-empty name has to be provided"
-          , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
-          }
-        ]
-      , [ "binary name"
-        , { "type": "if"
-          , "cond": {"type": "var", "name": "stage"}
-          , "else": {"type": "var", "name": "base name"}
-          , "then":
-            { "type": "join"
-            , "separator": "/"
-            , "$1":
-              [ {"type": "var", "name": "stage"}
-              , {"type": "var", "name": "base name"}
-              ]
-            }
-          }
-        ]
       , [ "link-args"
-        , { "type": "nub_right"
+        , { "type": "++"
           , "$1":
-            { "type": "++"
-            , "$1":
-              [ {"type": "keys", "$1": {"type": "var", "name": "objects"}}
-              , {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
-              ]
-            }
-          }
-        ]
-      , [ "binary"
-        , { "type": "ACTION"
-          , "outs": [{"type": "var", "name": "binary name"}]
-          , "inputs":
-            { "type": "disjoint_map_union"
-            , "$1":
-              [ {"type": "var", "name": "objects"}
-              , {"type": "var", "name": "link-deps"}
-              ]
-            }
-          , "cmd":
-            { "type": "++"
-            , "$1":
-              [ [ {"type": "var", "name": "CXX"}
-                , "-o"
-                , {"type": "var", "name": "binary name"}
-                ]
-              , {"type": "var", "name": "CXXFLAGS"}
-              , {"type": "var", "name": "link-args"}
-              ]
-            }
-          , "env": {"type": "var", "name": "ENV"}
+            [ {"type": "CALL_EXPRESSION", "name": "link-args-deps"}
+            , {"type": "FIELD", "name": "private-ldflags"}
+            ]
           }
         ]
+      , ["binary", {"type": "CALL_EXPRESSION", "name": "binary"}]
       , [ "staged test binary"
         , { "type": "map_union"
           , "$1":
@@ -256,6 +216,13 @@
             }
           }
         ]
+      , [ "test-name"
+        , { "type": "join"
+          , "separator": "/"
+          , "$1":
+            [{"type": "var", "name": "stage"}, {"type": "var", "name": "name"}]
+          }
+        ]
       , [ "test-results"
         , { "type": "ACTION"
           , "outs": ["result", "stdout", "stderr", "time-start", "time-stop"]
@@ -286,13 +253,13 @@
           , "fail_message":
             { "type": "join"
             , "$1":
-              ["CC test ", {"type": "var", "name": "binary name"}, " failed"]
+              ["CC test ", {"type": "var", "name": "test-name"}, " failed"]
             }
           }
         ]
       , [ "runfiles"
         , { "type": "singleton_map"
-          , "key": {"type": "var", "name": "base name"}
+          , "key": {"type": "var", "name": "name"}
           , "value":
             {"type": "TREE", "$1": {"type": "var", "name": "test-results"}}
           }
diff --git a/rules/shell/test/EXPRESSIONS b/rules/shell/test/EXPRESSIONS
index 24bf9ec1..444de921 100644
--- a/rules/shell/test/EXPRESSIONS
+++ b/rules/shell/test/EXPRESSIONS
@@ -1,5 +1,13 @@
 { "test-action":
-  { "vars": ["name", "test.sh", "ATTEMPT", "TEST_ENV"]
+  { "vars":
+    [ "TEST_ENV"
+    , "ATTEMPT"
+    , "name"
+    , "test.sh"
+    , "keep"
+    , "runner"
+    , "deps-fieldname"
+    ]
   , "imports":
     { "artifacts_list": ["./", "../..", "field_artifacts_list"]
     , "runfiles_list": ["./", "../..", "field_runfiles_list"]
@@ -12,7 +20,7 @@
           , "$1":
             { "type": "foreach"
             , "var": "runner"
-            , "range": {"type": "FIELD", "name": "runner"}
+            , "range": {"type": "var", "name": "runner"}
             , "body":
               { "type": "map_union"
               , "$1":
@@ -35,12 +43,17 @@
         , { "type": "TREE"
           , "$1":
             { "type": "disjoint_map_union"
-            , "msg": "Field 'deps' has to stage in a conflict free way"
+            , "msg":
+              [ "Field"
+              , {"type": "var", "name": "deps-fieldname"}
+              , "has to stage in a conflict free way"
+              ]
             , "$1":
               { "type": "++"
               , "$1":
                 { "type": "let*"
-                , "bindings": [["fieldname", "deps"]]
+                , "bindings":
+                  [["fieldname", {"type": "var", "name": "deps-fieldname"}]]
                 , "body":
                   [ {"type": "CALL_EXPRESSION", "name": "runfiles_list"}
                   , {"type": "CALL_EXPRESSION", "name": "artifacts_list"}
@@ -72,7 +85,7 @@
             [ ["result", "stdout", "stderr", "time-start", "time-stop"]
             , { "type": "foreach"
               , "var": "filename"
-              , "range": {"type": "FIELD", "name": "keep"}
+              , "range": {"type": "var", "name": "keep"}
               , "body":
                 { "type": "join"
                 , "$1": ["work/", {"type": "var", "name": "filename"}]
@@ -95,9 +108,7 @@
           }
         ]
       , [ "cmd"
-        , { "type": "++"
-          , "$1": [["./runner"], {"type": "FIELD", "name": "keep"}]
-          }
+        , {"type": "++", "$1": [["./runner"], {"type": "var", "name": "keep"}]}
         ]
       , [ "test_env"
         , {"type": "var", "name": "TEST_ENV", "default": {"type": "empty_map"}}
@@ -142,7 +153,7 @@
     }
   }
 , "test-result":
-  { "vars": ["name", "test.sh", "TEST_ENV"]
+  { "vars": ["TEST_ENV", "name", "test.sh", "keep", "runner", "deps-fieldname"]
   , "imports": {"action": "test-action"}
   , "expression":
     { "type": "let*"
diff --git a/rules/shell/test/RULES b/rules/shell/test/RULES
index 4242d94e..990e8d91 100644
--- a/rules/shell/test/RULES
+++ b/rules/shell/test/RULES
@@ -75,6 +75,9 @@
           , "$1": {"type": "join", "$1": {"type": "FIELD", "name": "name"}}
           }
         ]
+      , ["keep", {"type": "FIELD", "name": "keep"}]
+      , ["runner", {"type": "FIELD", "name": "runner"}]
+      , ["deps-fieldname", "deps"]
       ]
     , "body":
       { "type": "if"