[clang] 9aecbdf - [clang][DepScan] Allow ModuleDep to be const (#132968)

[via cfe-commits]

Author: Cyndy Ishida
Date: 2025-03-25T13:13:58-07:00
New Revision: 9aecbdf8ed787a8edd1b7f97a1c7fbf6e9d12515

URL: https://github.com/llvm/llvm-project/commit/9aecbdf8ed787a8edd1b7f97a1c7fbf6e9d12515
DIFF: https://github.com/llvm/llvm-project/commit/9aecbdf8ed787a8edd1b7f97a1c7fbf6e9d12515.diff

LOG: [clang][DepScan] Allow ModuleDep to be const (#132968)

This type can be exposed from C APIs, where instantiations of this type
are not expected to mutate after creation. To support this, mark the
lazy computation of build arguments mutable, as that is not intended to
otherwise mutate the state of these objects.


This was reviewed separately by @jansvoboda11

Added: 
    

Modified: 
    clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
    clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h b/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
index 422202caddfd4..ed150b467e3a1 100644
--- a/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
+++ b/clang/include/clang/Tooling/DependencyScanning/ModuleDepCollector.h
@@ -153,7 +153,7 @@ struct ModuleDeps {
 
   /// Get (or compute) the compiler invocation that can be used to build this
   /// module. Does not include argv[0].
-  const std::vector<std::string> &getBuildArguments();
+  const std::vector<std::string> &getBuildArguments() const;
 
 private:
   friend class ModuleDepCollector;
@@ -166,7 +166,8 @@ struct ModuleDeps {
   /// including transitive dependencies.
   std::vector<std::string> FileDeps;
 
-  std::variant<std::monostate, CowCompilerInvocation, std::vector<std::string>>
+  mutable std::variant<std::monostate, CowCompilerInvocation,
+                       std::vector<std::string>>
       BuildInfo;
 };
 

diff  --git a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
index d715ef874e002..364f156566855 100644
--- a/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
+++ b/clang/lib/Tooling/DependencyScanning/ModuleDepCollector.cpp
@@ -31,7 +31,9 @@ void ModuleDeps::forEachFileDep(llvm::function_ref<void(StringRef)> Cb) const {
   }
 }
 
-const std::vector<std::string> &ModuleDeps::getBuildArguments() {
+const std::vector<std::string> &ModuleDeps::getBuildArguments() const {
+  // FIXME: this operation is not thread safe and is expected to be called
+  // on a single thread. Otherwise it should be protected with a lock.
   assert(!std::holds_alternative<std::monostate>(BuildInfo) &&
          "Using uninitialized ModuleDeps");
   if (const auto *CI = std::get_if<CowCompilerInvocation>(&BuildInfo))