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

1 files changed, 74 insertions, 107 deletions

diff --git a/CC/test/RULES b/CC/test/RULES
index 0d7a9ba..b42b6c4 100644
--- a/CC/test/RULES
+++ b/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"}}
           }