Ninja: Use "deps = msvc" only for C and CXX (#15253)

The "/showIncludes" flag is only available with MS C and C++ compilers,
and on compilers that "simulate" them (like Intel for Windows).  Fix our
logic to choose this type only for MS tools with these languages.  All
other cases need to use "deps = gcc" and define DEP_FILE in the build
rule.

Source/cmNinjaTargetGenerator.cxx

@@ -200,21 +200,21 @@ cmNinjaTargetGenerator::ComputeFlagsForObject(cmSourceFile const* source,
   return flags;
 }
 
-
-bool cmNinjaTargetGenerator::needsDepFile(const std::string& lang)
+bool cmNinjaTargetGenerator::NeedDepTypeMSVC(const std::string& lang) const
 {
-  cmMakefile* mf = this->GetMakefile();
-
-  const bool usingMSVC = std::string("MSVC") ==
-                       (mf->GetDefinition("CMAKE_C_COMPILER_ID") ?
-                    mf->GetSafeDefinition("CMAKE_C_COMPILER_ID") :
-                    mf->GetSafeDefinition("CMAKE_CXX_COMPILER_ID"));
-
-  return !usingMSVC || lang == "RC";
+  if (lang == "C" || lang == "CXX")
+    {
+    cmMakefile* mf = this->GetMakefile();
+    return (
+      strcmp(mf->GetSafeDefinition("CMAKE_C_COMPILER_ID"), "MSVC") == 0 ||
+      strcmp(mf->GetSafeDefinition("CMAKE_CXX_COMPILER_ID"), "MSVC") == 0 ||
+      strcmp(mf->GetSafeDefinition("CMAKE_C_SIMULATE_ID"), "MSVC") == 0 ||
+      strcmp(mf->GetSafeDefinition("CMAKE_CXX_SIMULATE_ID"), "MSVC") == 0
+      );
+    }
+  return false;
 }
 
-
-
 // TODO: Refactor with
 // void cmMakefileTargetGenerator::WriteTargetLanguageFlags().
 std::string
@@ -391,22 +391,22 @@ cmNinjaTargetGenerator
 
   cmMakefile* mf = this->GetMakefile();
 
-  const std::string cId = mf->GetDefinition("CMAKE_C_COMPILER_ID")
-                          ? mf->GetSafeDefinition("CMAKE_C_COMPILER_ID")
-                          : mf->GetSafeDefinition("CMAKE_CXX_COMPILER_ID");
-  const std::string sId = mf->GetDefinition("CMAKE_C_SIMULATE_ID")
-                          ? mf->GetSafeDefinition("CMAKE_C_SIMULATE_ID")
-                          : mf->GetSafeDefinition("CMAKE_CXX_SIMULATE_ID");
-  const bool usingMSVC = (cId == "MSVC" || sId == "MSVC");
-
   // Tell ninja dependency format so all deps can be loaded into a database
   std::string deptype;
   std::string depfile;
   std::string cldeps;
   std::string flags = "$FLAGS";
-  if (usingMSVC)
+  if (this->NeedDepTypeMSVC(lang))
     {
-    if (!mf->GetIsSourceFileTryCompile() && lang == "RC")
+    deptype = "msvc";
+    depfile = "";
+    flags += " /showIncludes";
+    }
+  else if (lang == "RC" && this->NeedDepTypeMSVC("C"))
+    {
+    // For the MS resource compiler we need cmcldeps, but skip dependencies
+    // for source-file try_compile cases because they are always fresh.
+    if (!mf->GetIsSourceFileTryCompile())
       {
       deptype = "gcc";
       depfile = "$DEP_FILE";
@@ -419,12 +419,6 @@ cmNinjaTargetGenerator
       cldeps += mf->GetSafeDefinition("CMAKE_CL_SHOWINCLUDES_PREFIX");
       cldeps += "\" \"" + cl + "\" ";
       }
-    else
-      {
-      deptype = "msvc";
-      depfile = "";
-      flags += " /showIncludes";
-      }
     }
   else
     {
@@ -636,7 +630,7 @@ cmNinjaTargetGenerator
   cmNinjaVars vars;
   vars["FLAGS"] = this->ComputeFlagsForObject(source, language);
   vars["DEFINES"] = this->ComputeDefines(source, language);
-  if (needsDepFile(language)) {
+  if (!this->NeedDepTypeMSVC(language)) {
     vars["DEP_FILE"] =
             cmGlobalNinjaGenerator::EncodeDepfileSpace(objectFileName + ".d");
   }

Source/cmNinjaTargetGenerator.h

@@ -42,7 +42,7 @@ public:
 
   std::string GetTargetName() const;
 
-  bool needsDepFile(const std::string& lang);
+  bool NeedDepTypeMSVC(const std::string& lang) const;
 
 protected: