imports: Switch to Microsoft GSL implementation

... with two minor code base changes compared to previous
use of gsl-lite:

- dag.hpp: ActionNode::Ptr and ArtifactNode::Ptr are not
  wrapped in gsl::not_null<> anymore, due to lack of support
  for wrapping std::unique_ptr<>. More specifically, the
  move constructor is missing, rendering it impossible to
  use std::vector<>::emplace_back().

- utils/cpp/gsl.hpp: New header file added to implement the
  macros ExpectsAudit() and EnsureAudit(), asserts running
  only in debug builds, which were available in gsl-lite but
  are missing in MS GSL.

1 files changed, 8 insertions, 16 deletions

diff --git a/etc/defaults/CC/TARGETS.just b/etc/defaults/CC/TARGETS.just
index ea501e09..66033bef 100644
--- a/etc/defaults/CC/TARGETS.just
+++ b/etc/defaults/CC/TARGETS.just
@@ -12,21 +12,13 @@
     , "-pedantic-errors"
     ]
   , "ADD_CXXFLAGS":
-    { "type": "++"
-    , "$1":
-      [ [ "-std=c++20"
-        , "-Wall"
-        , "-Wextra"
-        , "-Wpedantic"
-        , "-Wsign-conversion"
-        , "-Werror"
-        , "-pedantic-errors"
-        ]
-      , { "type": "if"
-        , "cond": {"type": "var", "name": "DEBUG"}
-        , "then": ["-Dgsl_CONFIG_CONTRACT_CHECKING_AUDIT=1"]
-        }
-      ]
-    }
+    [ "-std=c++20"
+    , "-Wall"
+    , "-Wextra"
+    , "-Wpedantic"
+    , "-Wsign-conversion"
+    , "-Werror"
+    , "-pedantic-errors"
+    ]
   }
 }