Performance: Improve efficiency of source file lookup in cmMakefile

This reintroduces the change from commit v3.10.0-rc1~69^2 (Performance:
Improve efficiency of source file lookup in cmMakefile, 2017-08-17) with
some corrections.  The original was rolled back by commit
v3.10.0-rc1~52^2~1 (Revert "Performance: ...", 2017-09-25) due to
incompatibilities found.  The rollback was followed-up by addition of a
test for the offending case, and this revision passes the test.

1 files changed, 2 insertions, 8 deletions

diff --git a/Source/cmExtraCodeBlocksGenerator.cxx b/Source/cmExtraCodeBlocksGenerator.cxx
index 9c9b75b..76fc8f1 100644
--- a/Source/cmExtraCodeBlocksGenerator.cxx
+++ b/Source/cmExtraCodeBlocksGenerator.cxx
@@ -345,8 +345,7 @@ void cmExtraCodeBlocksGenerator::CreateNewProjectFile(
   all_files_map_t allFiles;
   std::vector<std::string> cFiles;
 
-  std::vector<std::string> const& srcExts =
-    this->GlobalGenerator->GetCMakeInstance()->GetSourceExtensions();
+  auto cm = this->GlobalGenerator->GetCMakeInstance();
 
   for (cmLocalGenerator* lg : lgs) {
     cmMakefile* makefile = lg->GetMakefile();
@@ -377,12 +376,7 @@ void cmExtraCodeBlocksGenerator::CreateNewProjectFile(
             std::string lang = s->GetLanguage();
             if (lang == "C" || lang == "CXX") {
               std::string const& srcext = s->GetExtension();
-              for (std::string const& ext : srcExts) {
-                if (srcext == ext) {
-                  isCFile = true;
-                  break;
-                }
-              }
+              isCFile = cm->IsSourceExtension(srcext);
             }
 
             std::string const& fullPath = s->GetFullPath();