From 9daa1012d4300b4bf987cdfe84a0d2e2972b8358 Mon Sep 17 00:00:00 2001
From: John Franklin Rickard <johnfranklin.rickard@gmail.com>
Date: Thu, 29 Jan 2026 19:55:26 +0100
Subject: [PATCH] cmGlobalGenerator: Avoid string copies by returning view

---
 Source/cmCoreTryCompile.cxx                | 4 ++--
 Source/cmGlobalGenerator.cxx               | 2 +-
 Source/cmGlobalGenerator.h                 | 2 +-
 Source/cmLocalVisualStudio7Generator.cxx   | 4 ++--
 Source/cmSourceFile.cxx                    | 4 ++--
 Source/cmVisualStudio10TargetGenerator.cxx | 5 +++--
 6 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/Source/cmCoreTryCompile.cxx b/Source/cmCoreTryCompile.cxx
index d5ac27e8fe..6befcbf890 100644
--- a/Source/cmCoreTryCompile.cxx
+++ b/Source/cmCoreTryCompile.cxx
@@ -575,9 +575,9 @@ cm::optional<cmTryCompileResult> cmCoreTryCompile::TryCompileCode(
     for (auto const& source : sources) {
       auto const& si = source.first;
       std::string ext = cmSystemTools::GetFilenameLastExtension(si);
-      std::string lang = gg->GetLanguageFromExtension(ext);
+      cm::string_view lang = gg->GetLanguageFromExtension(ext);
       if (!lang.empty()) {
-        testLangs.insert(lang);
+        testLangs.insert(std::string(lang));
       } else {
         std::ostringstream err;
         err << "Unknown extension \"" << ext
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index e3bed8b1e1..a42afa4f1e 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1100,7 +1100,7 @@ std::string cmGlobalGenerator::GetLanguageOutputExtension(
   return "";
 }
 
-std::string cmGlobalGenerator::GetLanguageFromExtension(
+cm::string_view cmGlobalGenerator::GetLanguageFromExtension(
   cm::string_view ext) const
 {
   // if there is an extension and it starts with . then move past the
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 7838b192af..83f76340d1 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -360,7 +360,7 @@ public:
   bool GetToolSupportsColor() const { return this->ToolSupportsColor; }
 
   //! return the language for the given extension
-  std::string GetLanguageFromExtension(cm::string_view ext) const;
+  cm::string_view GetLanguageFromExtension(cm::string_view ext) const;
   //! is an extension to be ignored
   bool IgnoreFile(cm::string_view ext) const;
   //! What is the preference for linkers and this language (None or Preferred)
diff --git a/Source/cmLocalVisualStudio7Generator.cxx b/Source/cmLocalVisualStudio7Generator.cxx
index a34820bca4..3d44ae8626 100644
--- a/Source/cmLocalVisualStudio7Generator.cxx
+++ b/Source/cmLocalVisualStudio7Generator.cxx
@@ -1486,8 +1486,8 @@ cmLocalVisualStudio7GeneratorFCInfo::cmLocalVisualStudio7GeneratorFCInfo(
     std::string configUpper = cmSystemTools::UpperCase(config);
     cmLVS7GFileConfig fc;
 
-    std::string lang =
-      lg->GlobalGenerator->GetLanguageFromExtension(sf.GetExtension());
+    std::string lang = std::string(
+      lg->GlobalGenerator->GetLanguageFromExtension(sf.GetExtension()));
     std::string const& sourceLang = lg->GetSourceFileLanguage(sf);
     bool needForceLang = false;
     // source file does not match its extension language
diff --git a/Source/cmSourceFile.cxx b/Source/cmSourceFile.cxx
index 822c880172..5f2cf3bf3e 100644
--- a/Source/cmSourceFile.cxx
+++ b/Source/cmSourceFile.cxx
@@ -287,9 +287,9 @@ void cmSourceFile::CheckLanguage(cm::string_view ext)
   // Try to identify the source file language from the extension.
   cmMakefile const* mf = this->Location.GetMakefile();
   cmGlobalGenerator* gg = mf->GetGlobalGenerator();
-  std::string l = gg->GetLanguageFromExtension(ext);
+  cm::string_view l = gg->GetLanguageFromExtension(ext);
   if (!l.empty()) {
-    this->Language = std::move(l);
+    this->Language = std::string(l);
   }
 }
 
diff --git a/Source/cmVisualStudio10TargetGenerator.cxx b/Source/cmVisualStudio10TargetGenerator.cxx
index f6cfc3c4d8..364fd566c1 100644
--- a/Source/cmVisualStudio10TargetGenerator.cxx
+++ b/Source/cmVisualStudio10TargetGenerator.cxx
@@ -2835,8 +2835,9 @@ void cmVisualStudio10TargetGenerator::OutputSourceSpecificFlags(
   // Force language if the file extension does not match.
   // Note that MSVC treats the upper-case '.C' extension as C and not C++.
   std::string const ext = sf.GetExtension();
-  std::string const extLang =
-    ext == "C"_s ? "C" : this->GlobalGenerator->GetLanguageFromExtension(ext);
+  cm::string_view const extLang = ext == "C"_s
+    ? "C"_s
+    : this->GlobalGenerator->GetLanguageFromExtension(ext);
   std::string lang = this->LocalGenerator->GetSourceFileLanguage(sf);
   char const* compileAs = nullptr;
   if (lang != extLang) {