3 files changed, 46 insertions, 0 deletions
diff --git a/Source/cmGlobalGenerator.cxx b/Source/cmGlobalGenerator.cxx
index ff6ad9d..0404715 100644
--- a/Source/cmGlobalGenerator.cxx
+++ b/Source/cmGlobalGenerator.cxx
@@ -1361,8 +1361,43 @@ void cmGlobalGenerator::ComputeBuildFileGenerators()
   }
 }
 
+bool cmGlobalGenerator::UnsupportedVariableIsDefined(const std::string& name,
+                                                     bool supported) const
+{
+  if (!supported && this->Makefiles.front()->GetDefinition(name)) {
+    std::ostringstream e;
+    /* clang-format off */
+    e <<
+      "Generator\n"
+      "  " << this->GetName() << "\n"
+      "does not support variable\n"
+      "  " << name << "\n"
+      "but it has been specified."
+      ;
+    /* clang-format on */
+    this->GetCMakeInstance()->IssueMessage(MessageType::FATAL_ERROR, e.str());
+    return true;
+  }
+
+  return false;
+}
+
 bool cmGlobalGenerator::Compute()
 {
+  // Make sure unsupported variables are not used.
+  if (this->UnsupportedVariableIsDefined("CMAKE_DEFAULT_BUILD_TYPE",
+                                         this->SupportsDefaultBuildType())) {
+    return false;
+  }
+  if (this->UnsupportedVariableIsDefined("CMAKE_CROSS_CONFIGS",
+                                         this->SupportsCrossConfigs())) {
+    return false;
+  }
+  if (this->UnsupportedVariableIsDefined("CMAKE_DEFAULT_CONFIGS",
+                                         this->SupportsDefaultConfigs())) {
+    return false;
+  }
+
   // Some generators track files replaced during the Generate.
   // Start with an empty vector:
   this->FilesReplacedDuringGenerate.clear();
diff --git a/Source/cmGlobalGenerator.h b/Source/cmGlobalGenerator.h
index 0e7e03d..ba997b2 100644
--- a/Source/cmGlobalGenerator.h
+++ b/Source/cmGlobalGenerator.h
@@ -455,6 +455,10 @@ public:
   /** Generate an <output>.rule file path for a given command output.  */
   virtual std::string GenerateRuleFile(std::string const& output) const;
 
+  virtual bool SupportsDefaultBuildType() const { return false; }
+  virtual bool SupportsCrossConfigs() const { return false; }
+  virtual bool SupportsDefaultConfigs() const { return false; }
+
   static std::string EscapeJSON(const std::string& s);
 
   void ProcessEvaluationFiles();
@@ -674,6 +678,9 @@ private:
 
   virtual const char* GetBuildIgnoreErrorsFlag() const { return nullptr; }
 
+  bool UnsupportedVariableIsDefined(const std::string& name,
+                                    bool supported) const;
+
   // Cache directory content and target files to be built.
   struct DirectoryContent
   {
diff --git a/Source/cmGlobalNinjaGenerator.h b/Source/cmGlobalNinjaGenerator.h
index 3db8356..5668dd1 100644
--- a/Source/cmGlobalNinjaGenerator.h
+++ b/Source/cmGlobalNinjaGenerator.h
@@ -640,6 +640,10 @@ public:
 
   bool ReadCacheEntriesForBuild(const cmState& state) override;
 
+  bool SupportsDefaultBuildType() const override { return true; }
+  bool SupportsCrossConfigs() const override { return true; }
+  bool SupportsDefaultConfigs() const override { return true; }
+
 protected:
   bool OpenBuildFileStreams() override;
   void CloseBuildFileStreams() override;