Features: FATAL_ERROR on compilers with no recorded features.

Users of the new target_compile_features command are expected to
check the existence of the CMAKE_CXX_COMPILE_FEATURES variable before
attempting to use it to require features.

1 files changed, 22 insertions, 2 deletions

diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 6ec40fb..07cfe12 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -4604,8 +4604,28 @@ AddRequiredTargetFeature(cmTarget *target, const std::string& feature,
 
   if (!featuresKnown || !*featuresKnown)
     {
-    // We know of no features for the compiler at all.
-    return true;
+    cmOStringStream e;
+    if (error)
+      {
+      e << "no";
+      }
+    else
+      {
+      e << "No";
+      }
+    e << " known features for compiler\n\""
+      << this->GetDefinition("CMAKE_" + lang + "_COMPILER_ID")
+      << "\"\nversion "
+      << this->GetDefinition("CMAKE_" + lang + "_COMPILER_VERSION") << ".";
+    if (error)
+      {
+      *error = e.str();
+      }
+    else
+      {
+      this->IssueMessage(cmake::FATAL_ERROR, e.str());
+      }
+    return false;
     }
 
   std::vector<std::string> availableFeatures;