cmLocalCommonGenerator: Save CMAKE_BUILD_TYPE on construction

Copy the value to our `ConfigName` member on construction to ensure it
is available even to code paths that run before `Generate`.  We once
needed to delay this lookup until `Generate` because the local
generators were at one time created before `Configure`.  Now they are
created at generate time which is late enough to expect
`CMAKE_BUILD_TYPE` to be available.

Without this, `cmGlobalUnixMakefileGenerator3::WriteConvenienceRules`
causes use of `ConfigName` before it is populated which breaks use of
source files that depend on the `$<CONFIG>` generator expression.

Fixes: #16889

1 files changed, 4 insertions, 8 deletions

diff --git a/Source/cmLocalCommonGenerator.cxx b/Source/cmLocalCommonGenerator.cxx
index d5f9d27..6524db4 100644
--- a/Source/cmLocalCommonGenerator.cxx
+++ b/Source/cmLocalCommonGenerator.cxx
@@ -16,14 +16,6 @@ cmLocalCommonGenerator::cmLocalCommonGenerator(cmGlobalGenerator* gg,
   : cmLocalGenerator(gg, mf)
   , WorkingDirectory(wd)
 {
-}
-
-cmLocalCommonGenerator::~cmLocalCommonGenerator()
-{
-}
-
-void cmLocalCommonGenerator::SetConfigName()
-{
   // Store the configuration name that will be generated.
   if (const char* config = this->Makefile->GetDefinition("CMAKE_BUILD_TYPE")) {
     // Use the build type given by the user.
@@ -34,6 +26,10 @@ void cmLocalCommonGenerator::SetConfigName()
   }
 }
 
+cmLocalCommonGenerator::~cmLocalCommonGenerator()
+{
+}
+
 std::string cmLocalCommonGenerator::GetTargetFortranFlags(
   cmGeneratorTarget const* target, std::string const& config)
 {