Add global generator factory method to get list of known platforms

Add a `cmGlobalGeneratorFactory::GetKnownPlatforms` method to return
a list of known possible values for `CMAKE_GENERATOR_PLATFORM`.
Implement the method for each generator by referencing the list of
possible values documented in `Help/generator/*.rst` for it.

Co-Author: Julien Jomier <julien.jomier@kitware.com>

Source/cmGlobalGeneratorFactory.h

@@ -38,6 +38,9 @@ public:
 
   /** Determine whether or not this generator supports platforms */
   virtual bool SupportsPlatform() const = 0;
+
+  /** Get the list of supported platforms name for this generator */
+  virtual std::vector<std::string> GetKnownPlatforms() const = 0;
 };
 
 template <class T>
@@ -77,6 +80,13 @@ public:
 
   /** Determine whether or not this generator supports platforms */
   bool SupportsPlatform() const override { return T::SupportsPlatform(); }
+
+  /** Get the list of supported platforms name for this generator */
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    // default is no platform supported
+    return std::vector<std::string>();
+  }
 };
 
 #endif

Source/cmGlobalVisualStudio10Generator.cxx

@@ -91,6 +91,15 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("Itanium");
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory* cmGlobalVisualStudio10Generator::NewFactory()

Source/cmGlobalVisualStudio11Generator.cxx

@@ -93,6 +93,22 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("ARM");
+
+    std::set<std::string> installedSDKs =
+      cmGlobalVisualStudio11Generator::GetInstalledWindowsCESDKs();
+    for (std::string const& i : installedSDKs) {
+      platforms.emplace_back(i);
+    }
+
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory* cmGlobalVisualStudio11Generator::NewFactory()

Source/cmGlobalVisualStudio12Generator.cxx

@@ -75,6 +75,15 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("ARM");
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory* cmGlobalVisualStudio12Generator::NewFactory()

Source/cmGlobalVisualStudio14Generator.cxx

@@ -75,6 +75,15 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("ARM");
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory* cmGlobalVisualStudio14Generator::NewFactory()

Source/cmGlobalVisualStudio9Generator.cxx

@@ -83,6 +83,22 @@ public:
 
   bool SupportsToolset() const override { return false; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("Itanium");
+    cmVisualStudioWCEPlatformParser parser;
+    parser.ParseVersion("9.0");
+    const std::vector<std::string>& availablePlatforms =
+      parser.GetAvailablePlatforms();
+    for (std::string const& i : availablePlatforms) {
+      platforms.emplace_back(i);
+    }
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory* cmGlobalVisualStudio9Generator::NewFactory()

Source/cmGlobalVisualStudioVersionedGenerator.cxx

@@ -149,6 +149,16 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("ARM");
+    platforms.emplace_back("ARM64");
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory*
@@ -214,6 +224,16 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return true; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    std::vector<std::string> platforms;
+    platforms.emplace_back("x64");
+    platforms.emplace_back("Win32");
+    platforms.emplace_back("ARM");
+    platforms.emplace_back("ARM64");
+    return platforms;
+  }
 };
 
 cmGlobalGeneratorFactory*

Source/cmGlobalXCodeGenerator.cxx

@@ -147,6 +147,11 @@ public:
 
   bool SupportsToolset() const override { return true; }
   bool SupportsPlatform() const override { return false; }
+
+  std::vector<std::string> GetKnownPlatforms() const override
+  {
+    return std::vector<std::string>();
+  }
 };
 
 cmGlobalXCodeGenerator::cmGlobalXCodeGenerator(

Source/cmake.cxx

@@ -976,6 +976,7 @@ void cmake::GetRegisteredGenerators(std::vector<GeneratorInfo>& generators,
       GeneratorInfo info;
       info.supportsToolset = gen->SupportsToolset();
       info.supportsPlatform = gen->SupportsPlatform();
+      info.supportedPlatforms = gen->GetKnownPlatforms();
       info.name = name;
       info.baseName = name;
       info.isAlias = false;

Source/cmake.h

@@ -104,6 +104,7 @@ public:
     std::string extraName;
     bool supportsToolset;
     bool supportsPlatform;
+    std::vector<std::string> supportedPlatforms;
     bool isAlias;
   };