Features: Refactor <LANG>_STANDARD update

In order to support generator expressions in target COMPILE_FEATURES
we apply them at generate time.  Move this step to the beginning of
generation instead of doing it on demand while collecting flags.
This avoids repeating the process unnecessarily, and will then allow
`cmLocalGenerator::AddCompilerRequirementFlag` to be used any time
during generation.

1 files changed, 25 insertions, 8 deletions

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 33e32d1..6c8f132 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -558,6 +558,31 @@ void cmLocalGenerator::ComputeTargetManifest()
   }
 }
 
+bool cmLocalGenerator::ComputeTargetCompileFeatures()
+{
+  // Collect the set of configuration types.
+  std::vector<std::string> configNames;
+  this->Makefile->GetConfigurations(configNames);
+  if (configNames.empty()) {
+    configNames.push_back("");
+  }
+
+  // Process compile features of all targets.
+  std::vector<cmGeneratorTarget*> targets = this->GetGeneratorTargets();
+  for (std::vector<cmGeneratorTarget*>::iterator t = targets.begin();
+       t != targets.end(); ++t) {
+    cmGeneratorTarget* target = *t;
+    for (std::vector<std::string>::iterator ci = configNames.begin();
+         ci != configNames.end(); ++ci) {
+      if (!target->ComputeCompileFeatures(*ci)) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
 bool cmLocalGenerator::IsRootMakefile() const
 {
   return !this->StateSnapshot.GetBuildsystemDirectoryParent().IsValid();
@@ -742,14 +767,6 @@ void cmLocalGenerator::AddCompileOptions(std::string& flags,
       this->AppendFlagEscape(flags, *i);
     }
   }
-  std::vector<std::string> features;
-  target->GetCompileFeatures(features, config);
-  for (std::vector<std::string>::const_iterator it = features.begin();
-       it != features.end(); ++it) {
-    if (!this->Makefile->AddRequiredTargetFeature(target->Target, *it)) {
-      return;
-    }
-  }
 
   for (std::map<std::string, std::string>::const_iterator it =
          target->GetMaxLanguageStandards().begin();