From e331367a898c6e0afa386c52fc7bd4d84d75ec29 Mon Sep 17 00:00:00 2001
From: Cristian Adam <cristian.adam@gmail.com>
Date: Sun, 3 Nov 2019 21:34:39 +0100
Subject: PCH: Add support for OBJC/OBJCXX languages

---
 Modules/Compiler/GNU.cmake           |  2 ++
 Modules/Platform/Windows-Clang.cmake |  3 ---
 Source/cmGeneratorTarget.cxx         | 34 ++++++++++++++++++++++++++++------
 Source/cmLocalGenerator.cxx          |  2 +-
 4 files changed, 31 insertions(+), 10 deletions(-)

diff --git a/Modules/Compiler/GNU.cmake b/Modules/Compiler/GNU.cmake
index e0ff174..6960571 100644
--- a/Modules/Compiler/GNU.cmake
+++ b/Modules/Compiler/GNU.cmake
@@ -13,6 +13,8 @@ include(Internal/CMakeCheckCompilerFlag)
 
 set(__pch_header_C "c-header")
 set(__pch_header_CXX "c++-header")
+set(__pch_header_OBJC "objective-c-header")
+set(__pch_header_OBJCXX "objective-c++-header")
 
 macro(__compiler_gnu lang)
   # Feature flags.
diff --git a/Modules/Platform/Windows-Clang.cmake b/Modules/Platform/Windows-Clang.cmake
index f226553..02864c6 100644
--- a/Modules/Platform/Windows-Clang.cmake
+++ b/Modules/Platform/Windows-Clang.cmake
@@ -8,9 +8,6 @@ if(__WINDOWS_CLANG)
 endif()
 set(__WINDOWS_CLANG 1)
 
-set(__pch_header_C "c-header")
-set(__pch_header_CXX "c++-header")
-
 macro(__windows_compiler_clang_gnu lang)
   set(CMAKE_LIBRARY_PATH_FLAG "-L")
   set(CMAKE_LINK_LIBRARY_FLAG "-l")
diff --git a/Source/cmGeneratorTarget.cxx b/Source/cmGeneratorTarget.cxx
index 949d9d9..f235af9 100644
--- a/Source/cmGeneratorTarget.cxx
+++ b/Source/cmGeneratorTarget.cxx
@@ -3334,9 +3334,11 @@ std::vector<BT<std::string>> cmGeneratorTarget::GetPrecompileHeaders(
 std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
                                             const std::string& language) const
 {
-  if (language != "C" && language != "CXX") {
+  if (language != "C" && language != "CXX" && language != "OBJC" &&
+      language != "OBJCXX") {
     return std::string();
   }
+
   if (this->GetPropertyAsBool("DISABLE_PRECOMPILE_HEADERS")) {
     return std::string();
   }
@@ -3367,8 +3369,15 @@ std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
       filename = generatorTarget->ObjectDirectory;
     }
 
+    const std::map<std::string, std::string> languageToExtension = {
+      { "C", ".h" },
+      { "CXX", ".hxx" },
+      { "OBJC", ".objc.h" },
+      { "OBJCXX", ".objcxx.hxx" }
+    };
+
     filename = cmStrCat(filename, "CMakeFiles/", generatorTarget->GetName(),
-                        ".dir/cmake_pch", ((language == "C") ? ".h" : ".hxx"));
+                        ".dir/cmake_pch", languageToExtension.at(language));
 
     const std::string filename_tmp = cmStrCat(filename, ".tmp");
     if (!pchReuseFrom) {
@@ -3418,7 +3427,8 @@ std::string cmGeneratorTarget::GetPchHeader(const std::string& config,
 std::string cmGeneratorTarget::GetPchSource(const std::string& config,
                                             const std::string& language) const
 {
-  if (language != "C" && language != "CXX") {
+  if (language != "C" && language != "CXX" && language != "OBJC" &&
+      language != "OBJCXX") {
     return std::string();
   }
   const auto inserted =
@@ -3444,9 +3454,20 @@ std::string cmGeneratorTarget::GetPchSource(const std::string& config,
 
     // For GCC the source extension will be tranformed into .h[xx].gch
     if (!this->Makefile->IsOn("CMAKE_LINK_PCH")) {
-      filename += ((language == "C") ? ".h.c" : ".hxx.cxx");
+      const std::map<std::string, std::string> languageToExtension = {
+        { "C", ".h.c" },
+        { "CXX", ".hxx.cxx" },
+        { "OBJC", ".objc.h.m" },
+        { "OBJCXX", ".objcxx.hxx.mm" }
+      };
+
+      filename += languageToExtension.at(language);
     } else {
-      filename += ((language == "C") ? ".c" : ".cxx");
+      const std::map<std::string, std::string> languageToExtension = {
+        { "C", ".c" }, { "CXX", ".cxx" }, { "OBJC", ".m" }, { "OBJCXX", ".mm" }
+      };
+
+      filename += languageToExtension.at(language);
     }
 
     const std::string filename_tmp = cmStrCat(filename, ".tmp");
@@ -3464,7 +3485,8 @@ std::string cmGeneratorTarget::GetPchSource(const std::string& config,
 std::string cmGeneratorTarget::GetPchFileObject(const std::string& config,
                                                 const std::string& language)
 {
-  if (language != "C" && language != "CXX") {
+  if (language != "C" && language != "CXX" && language != "OBJC" &&
+      language != "OBJCXX") {
     return std::string();
   }
   const auto inserted =
diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index a2eb1b9..00bd8af 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2266,7 +2266,7 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
   std::vector<cmSourceFile*> sources;
   target->GetSourceFiles(sources, buildType);
 
-  for (const std::string& lang : { "C", "CXX" }) {
+  for (const std::string& lang : { "C", "CXX", "OBJC", "OBJCXX" }) {
     auto langSources =
       std::count_if(sources.begin(), sources.end(), [lang](cmSourceFile* sf) {
         return lang == sf->GetLanguage() &&
-- 
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