Genex: Enable COMPILE_LANGUAGE for INCLUDE_DIRECTORIES with VS and Xcode

The set of compile flags used for a target's C and C++ sources is based
on the linker language.  By default this is always the C++ flags if any
C++ sources appear in the target, and otherwise the C flags.  Therefore
we can define the `COMPILE_LANGUAGE` generator expression in
`INCLUDE_DIRECTORIES` to match the selected language.

This is not exactly the same as for other generators, but is the best VS
and Xcode can do.  It is also sufficient for many use cases since the
set of include directories for C and C++ is frequently similar but may
be distinct from those for other languages like CUDA.

Fixes: #17435

14 files changed, 31 insertions, 59 deletions

diff --git a/Tests/CMakeCommands/target_include_directories/CMakeLists.txt b/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
index d57556a..8713d99 100644
--- a/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
+++ b/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
@@ -42,17 +42,17 @@ add_executable(consumer
   "${CMAKE_CURRENT_SOURCE_DIR}/consumer.cpp"
 )
 
-if (CMAKE_GENERATOR MATCHES "Makefiles" OR CMAKE_GENERATOR MATCHES "Ninja")
-  target_sources(consumer PRIVATE
-    "${CMAKE_CURRENT_SOURCE_DIR}/consumer.c"
-  )
-  target_include_directories(consumer
-    PRIVATE
-      $<$<COMPILE_LANGUAGE:CXX>:${CMAKE_CURRENT_SOURCE_DIR}/cxx_only>
-      $<$<COMPILE_LANGUAGE:C>:${CMAKE_CURRENT_SOURCE_DIR}/c_only>
-  )
+target_sources(consumer PRIVATE
+  "${CMAKE_CURRENT_SOURCE_DIR}/consumer.c"
+)
+target_include_directories(consumer
+  PRIVATE
+    $<$<COMPILE_LANGUAGE:CXX>:${CMAKE_CURRENT_SOURCE_DIR}/cxx_only>
+    $<$<COMPILE_LANGUAGE:C>:${CMAKE_CURRENT_SOURCE_DIR}/c_only>
+)
+if(CMAKE_GENERATOR MATCHES "Visual Studio|Xcode")
   target_compile_definitions(consumer
-    PRIVATE -DTEST_LANG_DEFINES
+    PRIVATE TEST_LANG_DEFINES_FOR_VISUAL_STUDIO_OR_XCODE
   )
 endif()
 
diff --git a/Tests/CMakeCommands/target_include_directories/consumer.c b/Tests/CMakeCommands/target_include_directories/consumer.c
index ae88f92..419c2d2 100644
--- a/Tests/CMakeCommands/target_include_directories/consumer.c
+++ b/Tests/CMakeCommands/target_include_directories/consumer.c
@@ -1,5 +1,13 @@
 
-#ifdef TEST_LANG_DEFINES
+// Visual Studio allows only one set of flags for C and C++.
+// In a target using C++ we pick the C++ flags even for C sources.
+#ifdef TEST_LANG_DEFINES_FOR_VISUAL_STUDIO_OR_XCODE
+#include "cxx_only.h"
+
+#ifndef CXX_ONLY_DEFINE
+#error Expected CXX_ONLY_DEFINE
+#endif
+#else
 #include "c_only.h"
 
 #ifndef C_ONLY_DEFINE
diff --git a/Tests/CMakeCommands/target_include_directories/consumer.cpp b/Tests/CMakeCommands/target_include_directories/consumer.cpp
index 0f8153b..1e018ad 100644
--- a/Tests/CMakeCommands/target_include_directories/consumer.cpp
+++ b/Tests/CMakeCommands/target_include_directories/consumer.cpp
@@ -1,12 +1,10 @@
 
 #include "consumer.h"
 #include "common.h"
+#include "cxx_only.h"
 #include "interfaceinclude.h"
 #include "publicinclude.h"
 #include "relative_dir.h"
-#ifdef TEST_LANG_DEFINES
-#include "cxx_only.h"
-#endif
 
 #ifdef PRIVATEINCLUDE_DEFINE
 #error Unexpected PRIVATEINCLUDE_DEFINE
@@ -32,11 +30,9 @@
 #error Expected CONSUMER_DEFINE
 #endif
 
-#ifdef TEST_LANG_DEFINES
 #ifndef CXX_ONLY_DEFINE
 #error Expected CXX_ONLY_DEFINE
 #endif
-#endif
 
 int main()
 {
diff --git a/Tests/CudaOnly/WithDefs/CMakeLists.txt b/Tests/CudaOnly/WithDefs/CMakeLists.txt
index 1a5599b..ffe4859 100644
--- a/Tests/CudaOnly/WithDefs/CMakeLists.txt
+++ b/Tests/CudaOnly/WithDefs/CMakeLists.txt
@@ -45,6 +45,11 @@ target_compile_definitions(CudaOnlyWithDefs
     -DDEF_LANG_IS_CUDA=$<COMPILE_LANGUAGE:CUDA>
   )
 
+target_include_directories(CudaOnlyWithDefs
+  PRIVATE
+    $<$<COMPILE_LANGUAGE:CUDA>:${CMAKE_CURRENT_SOURCE_DIR}/inc_cuda>
+)
+
 if(APPLE)
   # Help the static cuda runtime find the driver (libcuda.dyllib) at runtime.
   set_property(TARGET CudaOnlyWithDefs PROPERTY BUILD_RPATH ${CMAKE_CUDA_IMPLICIT_LINK_DIRECTORIES})
diff --git a/Tests/CudaOnly/WithDefs/inc_cuda/inc_cuda.h b/Tests/CudaOnly/WithDefs/inc_cuda/inc_cuda.h
new file mode 100644
index 0000000..e228b58
--- /dev/null
+++ b/Tests/CudaOnly/WithDefs/inc_cuda/inc_cuda.h
@@ -0,0 +1 @@
+#define INC_CUDA
diff --git a/Tests/CudaOnly/WithDefs/main.notcu b/Tests/CudaOnly/WithDefs/main.notcu
index 426eb62..3793d74 100644
--- a/Tests/CudaOnly/WithDefs/main.notcu
+++ b/Tests/CudaOnly/WithDefs/main.notcu
@@ -2,6 +2,11 @@
 #include <cuda_runtime.h>
 #include <iostream>
 
+#include <inc_cuda.h>
+#ifndef INC_CUDA
+#error "INC_CUDA not defined!"
+#endif
+
 #ifndef HOST_DEFINE
 #error "HOST_DEFINE not defined!"
 #endif
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index 8eb8568..edd6c79 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -351,8 +351,6 @@ add_RunCMake_test(IfacePaths_INCLUDE_DIRECTORIES TEST_DIR IfacePaths)
 set(IfacePaths_SOURCES_ARGS -DTEST_PROP=SOURCES)
 add_RunCMake_test(IfacePaths_SOURCES TEST_DIR IfacePaths)
 
-add_RunCMake_test(COMPILE_LANGUAGE-genex)
-
 # Matlab module related tests
 if(CMake_TEST_FindMatlab)
   add_RunCMake_test(FindMatlab)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt
deleted file mode 100644
index ef2163c..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt
+++ /dev/null
@@ -1,3 +0,0 @@
-cmake_minimum_required(VERSION 3.1)
-project(${RunCMake_TEST} NONE)
-include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt
deleted file mode 100644
index d00491f..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt
+++ /dev/null
@@ -1 +0,0 @@
-1
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt
deleted file mode 100644
index 0e13c48..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-CMake Error at IncludeDirectories.cmake:5 \(target_include_directories\):
-  Error evaluating generator expression:
-
-    \$<COMPILE_LANGUAGE:CXX>
-
-  \$<COMPILE_LANGUAGE:...> may only be used for COMPILE_OPTIONS,
-  COMPILE_DEFINITIONS, and file\(GENERATE\) with the Visual Studio generator.
-Call Stack \(most recent call first\):
-  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-Xcode.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-Xcode.txt
deleted file mode 100644
index 3f86dd4..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-Xcode.txt
+++ /dev/null
@@ -1,9 +0,0 @@
-CMake Error at IncludeDirectories.cmake:5 \(target_include_directories\):
-  Error evaluating generator expression:
-
-    \$<COMPILE_LANGUAGE:CXX>
-
-  \$<COMPILE_LANGUAGE:...> may only be used for COMPILE_OPTIONS,
-  COMPILE_DEFINITIONS, and file\(GENERATE\) with the Xcode generator.
-Call Stack \(most recent call first\):
-  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories.cmake b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories.cmake
deleted file mode 100644
index 31771f6..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories.cmake
+++ /dev/null
@@ -1,5 +0,0 @@
-
-enable_language(CXX)
-
-add_executable(main main.cpp)
-target_include_directories(main PRIVATE $<$<COMPILE_LANGUAGE:CXX>:anydir>)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/RunCMakeTest.cmake b/Tests/RunCMake/COMPILE_LANGUAGE-genex/RunCMakeTest.cmake
deleted file mode 100644
index 9ed1b67..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/RunCMakeTest.cmake
+++ /dev/null
@@ -1,9 +0,0 @@
-include(RunCMake)
-
-if (RunCMake_GENERATOR STREQUAL "Xcode")
-    set(RunCMake-stderr-file IncludeDirectories-stderr-Xcode.txt)
-    run_cmake(IncludeDirectories)
-elseif (RunCMake_GENERATOR MATCHES "Visual Studio")
-    set(RunCMake-stderr-file IncludeDirectories-stderr-VS.txt)
-    run_cmake(IncludeDirectories)
-endif()
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/main.cpp b/Tests/RunCMake/COMPILE_LANGUAGE-genex/main.cpp
deleted file mode 100644
index 766b775..0000000
--- a/Tests/RunCMake/COMPILE_LANGUAGE-genex/main.cpp
+++ /dev/null
@@ -1,5 +0,0 @@
-
-int main()
-{
-  return 0;
-}