Ninja: Refactor detection of MinGW tools on Windows

Check for CMAKE_COMPILER_IS_MINGW only after enabling a language when it
might actually be set.  Previously this worked by accident because the
check for working compiler or a second language enabled would cause the
code path to be taken.

Store UsingMinGW as an instance member of cmGlobalNinjaGenerator so that
it is reset on each reconfigure.  Otherwise cmake-gui cannot switch
between build trees for MinGW or non-MinGW tools.

Source/cmGlobalNinjaGenerator.cxx

@@ -96,7 +96,7 @@ std::string cmGlobalNinjaGenerator::EncodePath(const std::string &path)
 {
   std::string result = path;
 #ifdef _WIN32
-  if(UsingMinGW)
+  if (this->IsMinGW())
     cmSystemTools::ReplaceString(result, "\\", "/");
   else
     cmSystemTools::ReplaceString(result, "/", "\\");
@@ -484,6 +484,7 @@ cmGlobalNinjaGenerator::cmGlobalNinjaGenerator()
   , CompileCommandsStream(0)
   , Rules()
   , AllDependencies()
+  , UsingMinGW(false)
   , ComputingUnknownDependencies(false)
   , PolicyCMP0058(cmPolicies::WARN)
 {
@@ -544,23 +545,16 @@ void cmGlobalNinjaGenerator::Generate()
   this->CloseBuildFileStream();
 }
 
-// Implemented in all cmGlobaleGenerator sub-classes.
-// Used in:
-//   Source/cmMakefile.cxx:
 void cmGlobalNinjaGenerator
 ::EnableLanguage(std::vector<std::string>const& langs,
-                 cmMakefile* makefile,
+                 cmMakefile* mf,
                  bool optional)
 {
-  if (makefile->IsOn("CMAKE_COMPILER_IS_MINGW"))
-    {
-    UsingMinGW = true;
-    }
   if (std::find(langs.begin(), langs.end(), "Fortran") != langs.end())
     {
     cmSystemTools::Error("The Ninja generator does not support Fortran yet.");
     }
-  this->cmGlobalGenerator::EnableLanguage(langs, makefile, optional);
+  this->cmGlobalGenerator::EnableLanguage(langs, mf, optional);
   for(std::vector<std::string>::const_iterator l = langs.begin();
       l != langs.end(); ++l)
     {
@@ -568,11 +562,15 @@ void cmGlobalNinjaGenerator
       {
       continue;
       }
-    this->ResolveLanguageCompiler(*l, makefile, optional);
+    this->ResolveLanguageCompiler(*l, mf, optional);
     }
+#ifdef _WIN32
+  if (mf->IsOn("CMAKE_COMPILER_IS_MINGW"))
+    {
+    this->UsingMinGW = true;
+    }
+#endif
 }
-
-bool cmGlobalNinjaGenerator::UsingMinGW = false;
 
 // Implemented by:
 //   cmGlobalUnixMakefileGenerator3

Source/cmGlobalNinjaGenerator.h

@@ -63,7 +63,7 @@ public:
 
   static std::string EncodeIdent(const std::string &ident, std::ostream &vars);
   static std::string EncodeLiteral(const std::string &lit);
-  static std::string EncodePath(const std::string &path);
+  std::string EncodePath(const std::string &path);
   static std::string EncodeDepfileSpace(const std::string &path);
 
   /**
@@ -155,9 +155,7 @@ public:
                            const cmNinjaDeps& targets,
                            const std::string& comment = "");
 
-
-  static bool IsMinGW() { return UsingMinGW; }
-
+  bool IsMinGW() const { return this->UsingMinGW; }
 
 public:
   /// Default constructor.
@@ -362,6 +360,8 @@ private:
   /// The set of dependencies to add to the "all" target.
   cmNinjaDeps AllDependencies;
 
+  bool UsingMinGW;
+
   /// The set of custom commands we have seen.
   std::set<cmCustomCommand const*> CustomCommands;
 
@@ -385,9 +385,6 @@ private:
 
   typedef std::map<std::string, cmTarget*> TargetAliasMap;
   TargetAliasMap TargetAliases;
-
-  static bool UsingMinGW;
-
 };
 
 #endif // ! cmGlobalNinjaGenerator_h

Source/cmNinjaTargetGenerator.cxx

@@ -175,7 +175,7 @@ cmNinjaTargetGenerator::ComputeFlagsForObject(cmSourceFile const* source,
                                         // needed by cmcldeps
                                             false,
                                             this->GetConfigName());
-    if(cmGlobalNinjaGenerator::IsMinGW())
+    if (this->GetGlobalGenerator()->IsMinGW())
       cmSystemTools::ReplaceString(includeFlags, "\\", "/");
 
     this->LocalGenerator->AppendFlags(languageFlags, includeFlags);