From 476c6a89109d9737715c74bf3458628b665c4c8d Mon Sep 17 00:00:00 2001
From: Cristian Adam <cristian.adam@gmail.com>
Date: Mon, 11 Apr 2022 10:50:22 -0700
Subject: PCH: Fix Xcode non-pch language exclusion

Fix a regression caused by commit bbcdac4e5d (PCH: Fix all-language
precompile header support in Xcode, 2021-08-07, v3.22.0-rc1~140^2).

Fixes: #23138
---
 Source/cmLocalGenerator.cxx                             | 10 ++++++----
 .../PrecompileHeaders/PchIncludedOneLanguage.cmake      | 17 +++++++++++++++++
 Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake     |  1 +
 3 files changed, 24 insertions(+), 4 deletions(-)
 create mode 100644 Tests/RunCMake/PrecompileHeaders/PchIncludedOneLanguage.cmake

diff --git a/Source/cmLocalGenerator.cxx b/Source/cmLocalGenerator.cxx
index fc5e6e5..feea49f 100644
--- a/Source/cmLocalGenerator.cxx
+++ b/Source/cmLocalGenerator.cxx
@@ -2510,12 +2510,12 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
     static const std::array<std::string, 4> langs = { { "C", "CXX", "OBJC",
                                                         "OBJCXX" } };
 
-    bool haveAnyPch = false;
+    std::set<std::string> pchLangSet;
     if (this->GetGlobalGenerator()->IsXcode()) {
       for (const std::string& lang : langs) {
         const std::string pchHeader = target->GetPchHeader(config, lang, "");
         if (!pchHeader.empty()) {
-          haveAnyPch = true;
+          pchLangSet.emplace(lang);
         }
       }
     }
@@ -2560,9 +2560,11 @@ void cmLocalGenerator::AddPchDependencies(cmGeneratorTarget* target)
         const std::string pchHeader = target->GetPchHeader(config, lang, arch);
 
         if (pchSource.empty() || pchHeader.empty()) {
-          if (this->GetGlobalGenerator()->IsXcode() && haveAnyPch) {
+          if (this->GetGlobalGenerator()->IsXcode() && !pchLangSet.empty()) {
             for (auto* sf : sources) {
-              sf->SetProperty("SKIP_PRECOMPILE_HEADERS", "ON");
+              if (pchLangSet.find(sf->GetLanguage()) == pchLangSet.end()) {
+                sf->SetProperty("SKIP_PRECOMPILE_HEADERS", "ON");
+              }
             }
           }
           continue;
diff --git a/Tests/RunCMake/PrecompileHeaders/PchIncludedOneLanguage.cmake b/Tests/RunCMake/PrecompileHeaders/PchIncludedOneLanguage.cmake
new file mode 100644
index 0000000..dd582ac
--- /dev/null
+++ b/Tests/RunCMake/PrecompileHeaders/PchIncludedOneLanguage.cmake
@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 3.16)
+project(PchIncludedAllLanguages C CXX)
+
+if(CMAKE_CXX_COMPILE_OPTIONS_USE_PCH)
+  add_definitions(-DHAVE_PCH_SUPPORT)
+endif()
+
+add_executable(main
+  main.cpp
+  empty.c
+  pch-included.cpp
+)
+
+target_precompile_headers(main PRIVATE $<$<COMPILE_LANGUAGE:CXX>:${CMAKE_CURRENT_SOURCE_DIR}/pch.h>)
+
+enable_testing()
+add_test(NAME main COMMAND main)
diff --git a/Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake b/Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake
index ca5b52e..29611ae 100644
--- a/Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake
+++ b/Tests/RunCMake/PrecompileHeaders/RunCMakeTest.cmake
@@ -29,4 +29,5 @@ if(RunCMake_GENERATOR MATCHES "Make|Ninja")
 endif()
 run_test(PchReuseFromObjLib)
 run_test(PchIncludedAllLanguages)
+run_test(PchIncludedOneLanguage)
 run_test(PchLibObjLibExe)
-- 
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