Ninja: Centralized required Ninja version numbers and comparisons.

Source/cmGlobalNinjaGenerator.cxx

@@ -1256,7 +1256,7 @@ std::string cmGlobalNinjaGenerator::ninjaCmd() const
   return "ninja";
 }
 
-std::string cmGlobalNinjaGenerator::ninjaVersion() const
+std::string cmGlobalNinjaGenerator::CurrentNinjaVersion() const
 {
   std::string version;
   std::string command = ninjaCmd() + " --version";
@@ -1264,13 +1264,14 @@ std::string cmGlobalNinjaGenerator::ninjaVersion() const
                                   &version, 0, 0, 0,
                                   cmSystemTools::OUTPUT_NONE);
 
-  return version;
+  return cmSystemTools::TrimWhitespace(version);
 }
 
 bool cmGlobalNinjaGenerator::SupportsConsolePool() const
 {
   return cmSystemTools::VersionCompare(cmSystemTools::OP_LESS,
-                                       ninjaVersion().c_str(), "1.5") == false;
+    CurrentNinjaVersion().c_str(),
+    RequiredNinjaVersionForConsolePool().c_str()) == false;
 }
 
 void cmGlobalNinjaGenerator::WriteTargetClean(std::ostream& os)

Source/cmGlobalNinjaGenerator.h

@@ -299,8 +299,10 @@ public:
 
   virtual void ComputeTargetObjectDirectory(cmGeneratorTarget* gt) const;
 
-  std::string ninjaVersion() const;
-
+  std::string CurrentNinjaVersion() const;
+  // Ninja generator uses 'deps' and 'msvc_deps_prefix' introduced in 1.3
+  static std::string RequiredNinjaVersion() { return "1.3"; }
+  static std::string RequiredNinjaVersionForConsolePool() { return "1.5"; }
   bool SupportsConsolePool() const;
 
 protected:

Source/cmLocalNinjaGenerator.cxx

@@ -193,16 +193,14 @@ void cmLocalNinjaGenerator::WriteProjectHeader(std::ostream& os)
 void cmLocalNinjaGenerator::WriteNinjaRequiredVersion(std::ostream& os)
 {
   // Default required version
-  // Ninja generator uses 'deps' and 'msvc_deps_prefix' introduced in 1.3
-  std::string requiredVersion = "1.3";
+  std::string requiredVersion =
+      this->GetGlobalNinjaGenerator()->RequiredNinjaVersion();
 
   // Ninja generator uses the 'console' pool if available (>= 1.5)
-  std::string usedVersion = this->GetGlobalNinjaGenerator()->ninjaVersion();
-  if(cmSystemTools::VersionCompare(cmSystemTools::OP_LESS,
-                                   usedVersion.c_str(),
-                                   "1.5") ==  false)
+  if(this->GetGlobalNinjaGenerator()->SupportsConsolePool())
     {
-      requiredVersion = "1.5";
+    requiredVersion =
+      this->GetGlobalNinjaGenerator()->RequiredNinjaVersionForConsolePool();
     }
 
   cmGlobalNinjaGenerator::WriteComment(os,