LINK_WHAT_YOU_USE feature: externalize configuration

Currently, this feature is only supported on ELF platforms. So, the property
LINK_WHAT_YOU_USE will be ignored for other plateforms.
Moreover, flags and commands are now controled by CMake variables.

Fixes: #20174

1 files changed, 24 insertions, 0 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index a14f085..6b88a03 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -3047,6 +3047,30 @@ void cmLocalGenerator::AppendPositionIndependentLinkerFlags(
   }
 }
 
+bool cmLocalGenerator::AppendLWYUFlags(std::string& flags,
+                                       const cmGeneratorTarget* target,
+                                       const std::string& lang)
+{
+  auto useLWYU = target->GetPropertyAsBool("LINK_WHAT_YOU_USE") &&
+    (target->GetType() == cmStateEnums::TargetType::EXECUTABLE ||
+     target->GetType() == cmStateEnums::TargetType::SHARED_LIBRARY ||
+     target->GetType() == cmStateEnums::TargetType::MODULE_LIBRARY);
+
+  if (useLWYU) {
+    const auto& lwyuFlag = this->GetMakefile()->GetSafeDefinition(
+      cmStrCat("CMAKE_", lang, "_LINK_WHAT_YOU_USE_FLAG"));
+    useLWYU = !lwyuFlag.empty();
+
+    if (useLWYU) {
+      std::vector<BT<std::string>> lwyuOpts;
+      lwyuOpts.emplace_back(lwyuFlag);
+      this->AppendFlags(flags, target->ResolveLinkerWrapper(lwyuOpts, lang));
+    }
+  }
+
+  return useLWYU;
+}
+
 void cmLocalGenerator::AppendCompileOptions(std::string& options,
                                             std::string const& options_list,
                                             const char* regex) const