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, 3 insertions, 2 deletions

diff --git a/src/buildtool/storage/target_cache_entry.cpp b/src/buildtool/storage/target_cache_entry.cpp
index 683b2f02..6e1f3187 100644
--- a/src/buildtool/storage/target_cache_entry.cpp
+++ b/src/buildtool/storage/target_cache_entry.cpp
@@ -20,6 +20,7 @@
 
 #include "src/buildtool/logging/log_level.hpp"
 #include "src/buildtool/logging/logger.hpp"
+#include "src/utils/cpp/gsl.hpp"
 
 auto TargetCacheEntry::FromTarget(
     AnalysedTargetPtr const& target,
@@ -48,9 +49,9 @@ auto TargetCacheEntry::ToResult() const noexcept
     auto const& desc = ArtifactDescription::FromJson(json);
     // The assumption is that all artifacts mentioned in a target cache
     // entry are KNOWN to the remote side.
-    gsl_ExpectsAudit(desc and desc->IsKnown());
+    ExpectsAudit(desc and desc->IsKnown());
     auto const& info = desc->ToArtifact().Info();
-    gsl_ExpectsAudit(info);
+    ExpectsAudit(info);
     return *info;
 }