From 71f15be957b1a4fc37edbfd70809c759e92227a2 Mon Sep 17 00:00:00 2001
From: Brad King <brad.king@kitware.com>
Date: Tue, 19 Oct 2021 11:28:40 -0400
Subject: VS: Fix compilation of single source with PCH in Unity Build

Sources that are part of a unity build are normally not compiled
individually.  However, the VS IDE allows a single source to be
compiled.  This can also be achieved on the command line:

    msbuild my.vcxproj ... -t:ClCompile -p:SelectedFiles=<src>

where `<src>` is the path in the vcxproj `ClCompile` entry.

In a target with precompiled headers, the source needs PCH settings to
support individual compilation even if the normal unity build does not.
---
 Source/cmVisualStudio10TargetGenerator.cxx                |  3 ++-
 Tests/RunCMake/VS10Project/RunCMakeTest.cmake             | 15 +++++++++++++++
 .../RunCMake/VS10Project/UnityBuildPCH-build-check.cmake  | 10 ++++++++++
 Tests/RunCMake/VS10Project/UnityBuildPCH.c                |  4 ++++
 Tests/RunCMake/VS10Project/UnityBuildPCH.cmake            |  4 ++++
 Tests/RunCMake/VS10Project/UnityBuildPCH.h                |  1 +
 6 files changed, 36 insertions(+), 1 deletion(-)
 create mode 100644 Tests/RunCMake/VS10Project/UnityBuildPCH-build-check.cmake
 create mode 100644 Tests/RunCMake/VS10Project/UnityBuildPCH.c
 create mode 100644 Tests/RunCMake/VS10Project/UnityBuildPCH.cmake
 create mode 100644 Tests/RunCMake/VS10Project/UnityBuildPCH.h

diff --git a/Source/cmVisualStudio10TargetGenerator.cxx b/Source/cmVisualStudio10TargetGenerator.cxx
index 1ea0461..b792c03 100644
--- a/Source/cmVisualStudio10TargetGenerator.cxx
+++ b/Source/cmVisualStudio10TargetGenerator.cxx
@@ -2337,7 +2337,8 @@ void cmVisualStudio10TargetGenerator::WriteAllSources(Elem& e0)
         }
       }
 
-      if (si.Kind == cmGeneratorTarget::SourceKindObjectSource) {
+      if (si.Kind == cmGeneratorTarget::SourceKindObjectSource ||
+          si.Kind == cmGeneratorTarget::SourceKindUnityBatched) {
         this->OutputSourceSpecificFlags(e2, si.Source);
       }
       if (si.Source->GetPropertyAsBool("SKIP_PRECOMPILE_HEADERS")) {
diff --git a/Tests/RunCMake/VS10Project/RunCMakeTest.cmake b/Tests/RunCMake/VS10Project/RunCMakeTest.cmake
index d5ed136..f945b43 100644
--- a/Tests/RunCMake/VS10Project/RunCMakeTest.cmake
+++ b/Tests/RunCMake/VS10Project/RunCMakeTest.cmake
@@ -64,6 +64,21 @@ if (RunCMake_GENERATOR MATCHES "Visual Studio 1[0-4] 201[0-5]" OR
 else()
   run_cmake(UnityBuildNative)
   run_cmake(UnityBuildNativeGrouped)
+
+  function(run_UnityBuildPCH)
+    set(RunCMake_TEST_BINARY_DIR ${RunCMake_BINARY_DIR}/UnityBuildPCH-build)
+    run_cmake(UnityBuildPCH)
+    set(RunCMake_TEST_NO_CLEAN 1)
+    set(vcxproj "${RunCMake_TEST_BINARY_DIR}/UnityBuildPCH.vcxproj")
+    if(EXISTS "${vcxproj}")
+      file(STRINGS ${vcxproj} vcxproj_strings REGEX "ClCompile[^\n]*UnityBuildPCH\\.c")
+    endif()
+    if(vcxproj_strings MATCHES "Include=\"([^\"]+)\"")
+      set(src "${CMAKE_MATCH_1}")
+      run_cmake_command(UnityBuildPCH-build ${CMAKE_COMMAND} --build . --config Debug --target UnityBuildPCH -- -t:ClCompile -p:SelectedFiles=${src})
+    endif()
+  endfunction()
+  run_UnityBuildPCH()
 endif()
 
 run_cmake(VsDotnetTargetFramework)
diff --git a/Tests/RunCMake/VS10Project/UnityBuildPCH-build-check.cmake b/Tests/RunCMake/VS10Project/UnityBuildPCH-build-check.cmake
new file mode 100644
index 0000000..9043bb7
--- /dev/null
+++ b/Tests/RunCMake/VS10Project/UnityBuildPCH-build-check.cmake
@@ -0,0 +1,10 @@
+set(obj "${RunCMake_TEST_BINARY_DIR}/UnityBuildPCH.dir/Debug/UnityBuildPCH.obj")
+if(NOT EXISTS "${obj}")
+  set(RunCMake_TEST_FAILED "Expected object file does not exist:\n  ${obj}")
+  return()
+endif()
+set(lib "${RunCMake_TEST_BINARY_DIR}/Debug/UnityBuildPCH.lib")
+if(EXISTS "${lib}")
+  set(RunCMake_TEST_FAILED "Unexpected library file exists:\n  ${lib}")
+  return()
+endif()
diff --git a/Tests/RunCMake/VS10Project/UnityBuildPCH.c b/Tests/RunCMake/VS10Project/UnityBuildPCH.c
new file mode 100644
index 0000000..b96b068
--- /dev/null
+++ b/Tests/RunCMake/VS10Project/UnityBuildPCH.c
@@ -0,0 +1,4 @@
+int UnityBuildPCH(void)
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/VS10Project/UnityBuildPCH.cmake b/Tests/RunCMake/VS10Project/UnityBuildPCH.cmake
new file mode 100644
index 0000000..875ffec
--- /dev/null
+++ b/Tests/RunCMake/VS10Project/UnityBuildPCH.cmake
@@ -0,0 +1,4 @@
+enable_language(C)
+add_library(UnityBuildPCH STATIC UnityBuildPCH.c)
+target_precompile_headers(UnityBuildPCH PRIVATE UnityBuildPCH.h)
+set_property(TARGET UnityBuildPCH PROPERTY UNITY_BUILD ON)
diff --git a/Tests/RunCMake/VS10Project/UnityBuildPCH.h b/Tests/RunCMake/VS10Project/UnityBuildPCH.h
new file mode 100644
index 0000000..fa882cb
--- /dev/null
+++ b/Tests/RunCMake/VS10Project/UnityBuildPCH.h
@@ -0,0 +1 @@
+/* empty file */
-- 
cgit v0.12