3 files changed, 60 insertions, 6 deletions

diff --git a/Source/cmGeneratorExpressionEvaluator.cxx b/Source/cmGeneratorExpressionEvaluator.cxx
index 5f246f9..6692a92 100644
--- a/Source/cmGeneratorExpressionEvaluator.cxx
+++ b/Source/cmGeneratorExpressionEvaluator.cxx
@@ -1370,6 +1370,8 @@ static const struct CompileFeaturesNode : public cmGeneratorExpressionNode
       {
       std::vector<std::string> const& langAvailable
                                               = availableFeatures[lit->first];
+      const char* standardDefault = context->Makefile
+        ->GetDefinition("CMAKE_" + lit->first + "_STANDARD_DEFAULT");
       for (std::vector<std::string>::const_iterator it = lit->second.begin();
           it != lit->second.end(); ++it)
         {
@@ -1378,6 +1380,12 @@ static const struct CompileFeaturesNode : public cmGeneratorExpressionNode
           {
           return "0";
           }
+        if (standardDefault && !*standardDefault)
+          {
+          // This compiler has no notion of language standard levels.
+          // All features known for the language are always available.
+          continue;
+          }
         if (!context->Makefile->HaveStandardAvailable(target,
                                                       lit->first, *it))
           {
@@ -1386,8 +1394,7 @@ static const struct CompileFeaturesNode : public cmGeneratorExpressionNode
             const char* l = target->GetProperty(lit->first + "_STANDARD");
             if (!l)
               {
-              l = context->Makefile
-                  ->GetDefinition("CMAKE_" + lit->first + "_STANDARD_DEFAULT");
+              l = standardDefault;
               }
             assert(l);
             context->MaxLanguageStandard[target][lit->first] = l;
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index 834f705..af4c950 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2207,6 +2207,13 @@ AddCompilerRequirementFlag(std::string &flags, cmTarget* target,
     {
     return;
     }
+  const char* defaultStd
+      = this->Makefile->GetDefinition("CMAKE_" + lang + "_STANDARD_DEFAULT");
+  if (defaultStd && !*defaultStd)
+    {
+    // This compiler has no notion of language standard levels.
+    return;
+    }
   std::string stdProp = lang + "_STANDARD";
   const char *standardProp = target->GetProperty(stdProp);
   if (!standardProp)
@@ -2269,8 +2276,6 @@ AddCompilerRequirementFlag(std::string &flags, cmTarget* target,
                                 std::find(stds.begin(), stds.end(), standard);
   assert(stdIt != stds.end());
 
-  const char* defaultStd
-      = this->Makefile->GetDefinition("CMAKE_" + lang + "_STANDARD_DEFAULT");
   std::vector<std::string>::const_iterator defaultStdIt;
   if (defaultStd)
     {
diff --git a/Source/cmMakefile.cxx b/Source/cmMakefile.cxx
index 87e62d7..ba914e1 100644
--- a/Source/cmMakefile.cxx
+++ b/Source/cmMakefile.cxx
@@ -5253,6 +5253,27 @@ bool cmMakefile::
 HaveCStandardAvailable(cmTarget const* target,
                        const std::string& feature) const
 {
+  const char* defaultCStandard =
+    this->GetDefinition("CMAKE_C_STANDARD_DEFAULT");
+  if (!defaultCStandard)
+    {
+    std::ostringstream e;
+    e << "CMAKE_C_STANDARD_DEFAULT is not set.  COMPILE_FEATURES support "
+      "not fully configured for this compiler.";
+    this->IssueMessage(cmake::INTERNAL_ERROR, e.str());
+    // Return true so the caller does not try to lookup the default standard.
+    return true;
+    }
+  if (std::find_if(cmArrayBegin(C_STANDARDS), cmArrayEnd(C_STANDARDS),
+                cmStrCmp(defaultCStandard)) == cmArrayEnd(C_STANDARDS))
+    {
+    std::ostringstream e;
+    e << "The CMAKE_C_STANDARD_DEFAULT variable contains an "
+         "invalid value: \"" << defaultCStandard << "\".";
+    this->IssueMessage(cmake::INTERNAL_ERROR, e.str());
+    return false;
+    }
+
   bool needC90 = false;
   bool needC99 = false;
   bool needC11 = false;
@@ -5262,7 +5283,7 @@ HaveCStandardAvailable(cmTarget const* target,
   const char *existingCStandard = target->GetProperty("C_STANDARD");
   if (!existingCStandard)
     {
-    existingCStandard = this->GetDefinition("CMAKE_C_STANDARD_DEFAULT");
+    existingCStandard = defaultCStandard;
     }
 
   if (std::find_if(cmArrayBegin(C_STANDARDS), cmArrayEnd(C_STANDARDS),
@@ -5331,6 +5352,27 @@ bool cmMakefile::IsLaterStandard(std::string const& lang,
 bool cmMakefile::HaveCxxStandardAvailable(cmTarget const* target,
                                          const std::string& feature) const
 {
+  const char* defaultCxxStandard =
+    this->GetDefinition("CMAKE_CXX_STANDARD_DEFAULT");
+  if (!defaultCxxStandard)
+    {
+    std::ostringstream e;
+    e << "CMAKE_CXX_STANDARD_DEFAULT is not set.  COMPILE_FEATURES support "
+      "not fully configured for this compiler.";
+    this->IssueMessage(cmake::INTERNAL_ERROR, e.str());
+    // Return true so the caller does not try to lookup the default standard.
+    return true;
+    }
+  if (std::find_if(cmArrayBegin(CXX_STANDARDS), cmArrayEnd(CXX_STANDARDS),
+                cmStrCmp(defaultCxxStandard)) == cmArrayEnd(CXX_STANDARDS))
+    {
+    std::ostringstream e;
+    e << "The CMAKE_CXX_STANDARD_DEFAULT variable contains an "
+         "invalid value: \"" << defaultCxxStandard << "\".";
+    this->IssueMessage(cmake::INTERNAL_ERROR, e.str());
+    return false;
+    }
+
   bool needCxx98 = false;
   bool needCxx11 = false;
   bool needCxx14 = false;
@@ -5339,7 +5381,7 @@ bool cmMakefile::HaveCxxStandardAvailable(cmTarget const* target,
   const char *existingCxxStandard = target->GetProperty("CXX_STANDARD");
   if (!existingCxxStandard)
     {
-    existingCxxStandard = this->GetDefinition("CMAKE_CXX_STANDARD_DEFAULT");
+    existingCxxStandard = defaultCxxStandard;
     }
 
   if (std::find_if(cmArrayBegin(CXX_STANDARDS), cmArrayEnd(CXX_STANDARDS),