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/file_system/git_repo.cpp b/src/buildtool/file_system/git_repo.cpp
index 2e09f84d..d135875a 100644
--- a/src/buildtool/file_system/git_repo.cpp
+++ b/src/buildtool/file_system/git_repo.cpp
@@ -17,6 +17,7 @@
 #include <thread>
 
 #include "src/buildtool/logging/logger.hpp"
+#include "src/utils/cpp/gsl.hpp"
 #include "src/utils/cpp/hex_string.hpp"
 #include "src/utils/cpp/path.hpp"
 
@@ -1147,7 +1148,7 @@ auto GitRepo::ReadTree(std::string const& id, bool is_hex_id) const noexcept
     }
 
 #ifndef NDEBUG
-    gsl_EnsuresAudit(ValidateEntries(entries));
+    EnsuresAudit(ValidateEntries(entries));
 #endif
 
     return entries;
@@ -1160,7 +1161,7 @@ auto GitRepo::CreateTree(tree_entries_t const& entries) const noexcept
     return std::nullopt;
 #else
 #ifndef NDEBUG
-    gsl_ExpectsAudit(ValidateEntries(entries));
+    ExpectsAudit(ValidateEntries(entries));
 #endif  // NDEBUG
     // share the odb lock
     std::shared_lock lock{GetGitCAS()->mutex_};