Merge topic 'target-language-genex'

232a6883 Help: Add release notes for target-language-genex.
9e168941 File(GENERATE): Process genex evaluation files for each language.
b734fa44 Genex: Allow COMPILE_LANGUAGE when processing include directories.
0b945ea9 Genex: Allow COMPILE_LANGUAGE when processing compile definitions.
5c559f11 Genex: Enable use of COMPILE_LANGUAGE for compile options.
e387ce7d Genex: Add a COMPILE_LANGUAGE generator expression.
4a0128f4 VS6: Compute CMAKE_*_FLAGS and COMPILE_DEFINITIONS* only when needed

56 files changed, 404 insertions, 1 deletions

diff --git a/Tests/CMakeCommands/target_compile_definitions/CMakeLists.txt b/Tests/CMakeCommands/target_compile_definitions/CMakeLists.txt
index 14d40aa..f96283d 100644
--- a/Tests/CMakeCommands/target_compile_definitions/CMakeLists.txt
+++ b/Tests/CMakeCommands/target_compile_definitions/CMakeLists.txt
@@ -26,6 +26,21 @@ target_compile_definitions(consumer
   PRIVATE
 )
 
+if (CMAKE_GENERATOR MATCHES "Makefiles" OR CMAKE_GENERATOR MATCHES "Ninja")
+  target_sources(consumer PRIVATE
+    "${CMAKE_CURRENT_SOURCE_DIR}/consumer.c"
+  )
+  target_compile_definitions(consumer
+    PRIVATE
+      CONSUMER_LANG_$<COMPILE_LANGUAGE>
+      LANG_IS_CXX=$<COMPILE_LANGUAGE:CXX>
+      LANG_IS_C=$<COMPILE_LANGUAGE:C>
+  )
+  target_compile_definitions(consumer
+    PRIVATE -DTEST_LANG_DEFINES
+  )
+endif()
+
 add_definitions(-DSOME_DEF)
 add_library(imp UNKNOWN IMPORTED)
 get_target_property(_res imp COMPILE_DEFINITIONS)
diff --git a/Tests/CMakeCommands/target_compile_definitions/consumer.c b/Tests/CMakeCommands/target_compile_definitions/consumer.c
new file mode 100644
index 0000000..5796d96
--- /dev/null
+++ b/Tests/CMakeCommands/target_compile_definitions/consumer.c
@@ -0,0 +1,23 @@
+
+#ifdef TEST_LANG_DEFINES
+  #ifdef CONSUMER_LANG_CXX
+  #error Unexpected CONSUMER_LANG_CXX
+  #endif
+
+  #ifndef CONSUMER_LANG_C
+  #error Expected CONSUMER_LANG_C
+  #endif
+
+  #if !LANG_IS_C
+  #error Expected LANG_IS_C
+  #endif
+
+  #if LANG_IS_CXX
+  #error Unexpected LANG_IS_CXX
+  #endif
+#endif
+
+void consumer_c()
+{
+
+}
diff --git a/Tests/CMakeCommands/target_compile_definitions/consumer.cpp b/Tests/CMakeCommands/target_compile_definitions/consumer.cpp
index a391114..778f57e 100644
--- a/Tests/CMakeCommands/target_compile_definitions/consumer.cpp
+++ b/Tests/CMakeCommands/target_compile_definitions/consumer.cpp
@@ -15,4 +15,22 @@
 #error Expected DASH_D_DEFINE
 #endif
 
+#ifdef TEST_LANG_DEFINES
+  #ifndef CONSUMER_LANG_CXX
+  #error Expected CONSUMER_LANG_CXX
+  #endif
+
+  #ifdef CONSUMER_LANG_C
+  #error Unexpected CONSUMER_LANG_C
+  #endif
+
+  #if !LANG_IS_CXX
+  #error Expected LANG_IS_CXX
+  #endif
+
+  #if LANG_IS_C
+  #error Unexpected LANG_IS_C
+  #endif
+#endif
+
 int main() { return 0; }
diff --git a/Tests/CMakeCommands/target_compile_options/CMakeLists.txt b/Tests/CMakeCommands/target_compile_options/CMakeLists.txt
index 1d04639..35dd276 100644
--- a/Tests/CMakeCommands/target_compile_options/CMakeLists.txt
+++ b/Tests/CMakeCommands/target_compile_options/CMakeLists.txt
@@ -23,6 +23,21 @@ add_executable(consumer
   "${CMAKE_CURRENT_SOURCE_DIR}/consumer.cpp"
 )
 
+if (NOT CMAKE_GENERATOR MATCHES "Visual Studio")
+  target_sources(consumer PRIVATE
+    "${CMAKE_CURRENT_SOURCE_DIR}/consumer.c"
+  )
+  target_compile_options(consumer
+    PRIVATE
+      -DCONSUMER_LANG_$<COMPILE_LANGUAGE>
+      -DLANG_IS_CXX=$<COMPILE_LANGUAGE:CXX>
+      -DLANG_IS_C=$<COMPILE_LANGUAGE:C>
+  )
+  target_compile_definitions(consumer
+    PRIVATE -DTEST_LANG_DEFINES
+  )
+endif()
+
 target_compile_options(consumer
   PRIVATE $<$<CXX_COMPILER_ID:GNU>:$<TARGET_PROPERTY:target_compile_options,INTERFACE_COMPILE_OPTIONS>>
 )
diff --git a/Tests/CMakeCommands/target_compile_options/consumer.c b/Tests/CMakeCommands/target_compile_options/consumer.c
new file mode 100644
index 0000000..5796d96
--- /dev/null
+++ b/Tests/CMakeCommands/target_compile_options/consumer.c
@@ -0,0 +1,23 @@
+
+#ifdef TEST_LANG_DEFINES
+  #ifdef CONSUMER_LANG_CXX
+  #error Unexpected CONSUMER_LANG_CXX
+  #endif
+
+  #ifndef CONSUMER_LANG_C
+  #error Expected CONSUMER_LANG_C
+  #endif
+
+  #if !LANG_IS_C
+  #error Expected LANG_IS_C
+  #endif
+
+  #if LANG_IS_CXX
+  #error Unexpected LANG_IS_CXX
+  #endif
+#endif
+
+void consumer_c()
+{
+
+}
diff --git a/Tests/CMakeCommands/target_compile_options/consumer.cpp b/Tests/CMakeCommands/target_compile_options/consumer.cpp
index 1299606..c5882a5 100644
--- a/Tests/CMakeCommands/target_compile_options/consumer.cpp
+++ b/Tests/CMakeCommands/target_compile_options/consumer.cpp
@@ -15,4 +15,22 @@
 
 #endif
 
+#ifdef TEST_LANG_DEFINES
+  #ifndef CONSUMER_LANG_CXX
+  #error Expected CONSUMER_LANG_CXX
+  #endif
+
+  #ifdef CONSUMER_LANG_C
+  #error Unexpected CONSUMER_LANG_C
+  #endif
+
+  #if !LANG_IS_CXX
+  #error Expected LANG_IS_CXX
+  #endif
+
+  #if LANG_IS_C
+  #error Unexpected LANG_IS_C
+  #endif
+#endif
+
 int main() { return 0; }
diff --git a/Tests/CMakeCommands/target_include_directories/CMakeLists.txt b/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
index 661bbaa..d57556a 100644
--- a/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
+++ b/Tests/CMakeCommands/target_include_directories/CMakeLists.txt
@@ -42,6 +42,20 @@ 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_compile_definitions(consumer
+    PRIVATE -DTEST_LANG_DEFINES
+  )
+endif()
+
 target_include_directories(consumer
   PRIVATE
     $<TARGET_PROPERTY:target_include_directories,INTERFACE_INCLUDE_DIRECTORIES>
diff --git a/Tests/CMakeCommands/target_include_directories/c_only/c_only.h b/Tests/CMakeCommands/target_include_directories/c_only/c_only.h
new file mode 100644
index 0000000..29f68ee
--- /dev/null
+++ b/Tests/CMakeCommands/target_include_directories/c_only/c_only.h
@@ -0,0 +1,2 @@
+
+#define C_ONLY_DEFINE
diff --git a/Tests/CMakeCommands/target_include_directories/consumer.c b/Tests/CMakeCommands/target_include_directories/consumer.c
new file mode 100644
index 0000000..8821f5b
--- /dev/null
+++ b/Tests/CMakeCommands/target_include_directories/consumer.c
@@ -0,0 +1,10 @@
+
+#ifdef TEST_LANG_DEFINES
+  #include "c_only.h"
+
+  #ifndef C_ONLY_DEFINE
+  #error Expected C_ONLY_DEFINE
+  #endif
+#endif
+
+int consumer_c() { return 0; }
diff --git a/Tests/CMakeCommands/target_include_directories/consumer.cpp b/Tests/CMakeCommands/target_include_directories/consumer.cpp
index 7e3443e..649510c 100644
--- a/Tests/CMakeCommands/target_include_directories/consumer.cpp
+++ b/Tests/CMakeCommands/target_include_directories/consumer.cpp
@@ -4,6 +4,9 @@
 #include "interfaceinclude.h"
 #include "relative_dir.h"
 #include "consumer.h"
+#ifdef TEST_LANG_DEFINES
+  #include "cxx_only.h"
+#endif
 
 #ifdef PRIVATEINCLUDE_DEFINE
 #error Unexpected PRIVATEINCLUDE_DEFINE
@@ -29,4 +32,10 @@
 #error Expected CONSUMER_DEFINE
 #endif
 
+#ifdef TEST_LANG_DEFINES
+  #ifndef CXX_ONLY_DEFINE
+  #error Expected CXX_ONLY_DEFINE
+  #endif
+#endif
+
 int main() { return 0; }
diff --git a/Tests/CMakeCommands/target_include_directories/cxx_only/cxx_only.h b/Tests/CMakeCommands/target_include_directories/cxx_only/cxx_only.h
new file mode 100644
index 0000000..67289a4
--- /dev/null
+++ b/Tests/CMakeCommands/target_include_directories/cxx_only/cxx_only.h
@@ -0,0 +1,2 @@
+
+#define CXX_ONLY_DEFINE
diff --git a/Tests/RunCMake/CMakeLists.txt b/Tests/RunCMake/CMakeLists.txt
index eb42057..9f1256e 100644
--- a/Tests/RunCMake/CMakeLists.txt
+++ b/Tests/RunCMake/CMakeLists.txt
@@ -208,3 +208,5 @@ add_RunCMake_test(IfacePaths_SOURCES TEST_DIR IfacePaths)
 if(RPMBUILD_EXECUTABLE)
   add_RunCMake_test(CPackRPM)
 endif()
+
+add_RunCMake_test(COMPILE_LANGUAGE-genex)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt
new file mode 100644
index 0000000..ef2163c
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CMakeLists.txt
@@ -0,0 +1,3 @@
+cmake_minimum_required(VERSION 3.1)
+project(${RunCMake_TEST} NONE)
+include(${RunCMake_TEST}.cmake)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-result.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-VS.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-VS.txt
new file mode 100644
index 0000000..73b66ac
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-VS.txt
@@ -0,0 +1,8 @@
+CMake Error at CompileDefinitions.cmake:5 \(target_compile_definitions\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> may not be used with Visual Studio generators.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-Xcode.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-Xcode.txt
new file mode 100644
index 0000000..a1ed633
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions-stderr-Xcode.txt
@@ -0,0 +1,9 @@
+CMake Error at CompileDefinitions.cmake:5 \(target_compile_definitions\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> may only be used with COMPILE_OPTIONS with the
+  Xcode generator.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions.cmake b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions.cmake
new file mode 100644
index 0000000..7935d88
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileDefinitions.cmake
@@ -0,0 +1,5 @@
+
+enable_language(CXX)
+
+add_executable(main main.cpp)
+target_compile_definitions(main PRIVATE $<$<COMPILE_LANGUAGE:CXX>:-DANYTHING>)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-result.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-stderr-VS.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-stderr-VS.txt
new file mode 100644
index 0000000..e9e8e9f
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions-stderr-VS.txt
@@ -0,0 +1,8 @@
+CMake Error at CompileOptions.cmake:5 \(target_compile_options\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> may not be used with Visual Studio generators.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions.cmake b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions.cmake
new file mode 100644
index 0000000..6c92abc
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/CompileOptions.cmake
@@ -0,0 +1,5 @@
+
+enable_language(CXX)
+
+add_executable(main main.cpp)
+target_compile_options(main PRIVATE $<$<COMPILE_LANGUAGE:CXX>:-DANYTHING>)
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt
new file mode 100644
index 0000000..ec15068
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-VS.txt
@@ -0,0 +1,8 @@
+CMake Error at IncludeDirectories.cmake:5 \(target_include_directories\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> may not be used with Visual Studio generators.
+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
new file mode 100644
index 0000000..fdf92b2
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories-stderr-Xcode.txt
@@ -0,0 +1,9 @@
+CMake Error at IncludeDirectories.cmake:5 \(target_include_directories\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> may only be used with COMPILE_OPTIONS 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
new file mode 100644
index 0000000..31771f6
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/IncludeDirectories.cmake
@@ -0,0 +1,5 @@
+
+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
new file mode 100644
index 0000000..5e0a5f5
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/RunCMakeTest.cmake
@@ -0,0 +1,20 @@
+include(RunCMake)
+
+if (RunCMake_GENERATOR MATCHES "Visual Studio")
+    set(RunCMake-stderr-file CompileOptions-stderr-VS.txt)
+    run_cmake(CompileOptions)
+endif()
+if (RunCMake_GENERATOR STREQUAL "Xcode")
+    set(RunCMake-stderr-file CompileDefinitions-stderr-Xcode.txt)
+    run_cmake(CompileDefinitions)
+elseif (RunCMake_GENERATOR MATCHES "Visual Studio")
+    set(RunCMake-stderr-file CompileDefinitions-stderr-VS.txt)
+    run_cmake(CompileDefinitions)
+endif()
+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
new file mode 100644
index 0000000..31a1337
--- /dev/null
+++ b/Tests/RunCMake/COMPILE_LANGUAGE-genex/main.cpp
@@ -0,0 +1,5 @@
+
+int main()
+{
+    return 0;
+}
diff --git a/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex-result.txt b/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex-result.txt
new file mode 100644
index 0000000..573541a
--- /dev/null
+++ b/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex-result.txt
@@ -0,0 +1 @@
+0
diff --git a/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex.cmake b/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex.cmake
new file mode 100644
index 0000000..e2b081d
--- /dev/null
+++ b/Tests/RunCMake/File_Generate/COMPILE_LANGUAGE-genex.cmake
@@ -0,0 +1,12 @@
+
+enable_language(CXX C)
+
+add_library(empty empty.cpp empty.c)
+target_compile_options(empty
+  PRIVATE LANG_IS_$<COMPILE_LANGUAGE>
+)
+
+file(GENERATE
+  OUTPUT opts-$<COMPILE_LANGUAGE>.txt
+  CONTENT "$<TARGET_PROPERTY:empty,COMPILE_OPTIONS>\n"
+)
diff --git a/Tests/RunCMake/File_Generate/OutputConflict-stderr.txt b/Tests/RunCMake/File_Generate/OutputConflict-stderr.txt
index dbd39de..0abb7df 100644
--- a/Tests/RunCMake/File_Generate/OutputConflict-stderr.txt
+++ b/Tests/RunCMake/File_Generate/OutputConflict-stderr.txt
@@ -1,5 +1,5 @@
 CMake Error in CMakeLists.txt:
   Evaluation file to be written multiple times for different configurations
-  with different content:
+  or languages with different content:
 
   .*output.txt
diff --git a/Tests/RunCMake/File_Generate/RunCMakeTest.cmake b/Tests/RunCMake/File_Generate/RunCMakeTest.cmake
index 97f93d5..db344ef 100644
--- a/Tests/RunCMake/File_Generate/RunCMakeTest.cmake
+++ b/Tests/RunCMake/File_Generate/RunCMakeTest.cmake
@@ -17,6 +17,16 @@ if (NOT file_contents MATCHES "generated.cpp.rule")
   message(SEND_ERROR "Rule file not in target sources! ${file_contents}")
 endif()
 
+if (NOT RunCMake_GENERATOR MATCHES "Visual Studio")
+  run_cmake(COMPILE_LANGUAGE-genex)
+  foreach(l CXX C)
+    file(READ "${RunCMake_BINARY_DIR}/COMPILE_LANGUAGE-genex-build/opts-${l}.txt" l_defs)
+    if (NOT l_defs STREQUAL "LANG_IS_${l}\n")
+      message(FATAL_ERROR "File content does not match: ${l_defs}")
+    endif()
+  endforeach()
+endif()
+
 set(timeformat "%Y%j%H%M%S")
 
 file(REMOVE "${RunCMake_BINARY_DIR}/WriteIfDifferent-build/output_file.txt")
diff --git a/Tests/RunCMake/File_Generate/empty.c b/Tests/RunCMake/File_Generate/empty.c
new file mode 100644
index 0000000..563eef0
--- /dev/null
+++ b/Tests/RunCMake/File_Generate/empty.c
@@ -0,0 +1,8 @@
+
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+int empty_c()
+{
+  return 0;
+}
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-stderr.txt
new file mode 100644
index 0000000..789b4d0
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-add_custom_command.cmake:6 \(add_custom_command\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command.cmake
new file mode 100644
index 0000000..f4ba261
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_command.cmake
@@ -0,0 +1,8 @@
+
+enable_language(C)
+
+add_library(empty empty.c)
+
+add_custom_command(TARGET empty PRE_BUILD
+  COMMAND ${CMAKE_COMMAND} -E echo $<COMPILE_LANGUAGE>
+)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-stderr.txt
new file mode 100644
index 0000000..400fbc0
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-add_custom_target.cmake:4 \(add_custom_target\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target.cmake
new file mode 100644
index 0000000..4102623
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_custom_target.cmake
@@ -0,0 +1,6 @@
+
+enable_language(C)
+
+add_custom_target(empty
+  COMMAND ${CMAKE_COMMAND} -E echo $<COMPILE_LANGUAGE>
+)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-stderr.txt
new file mode 100644
index 0000000..e45bb02
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-add_executable.cmake:4 \(add_executable\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable.cmake
new file mode 100644
index 0000000..5c2ff35
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_executable.cmake
@@ -0,0 +1,4 @@
+
+enable_language(C)
+
+add_executable(empty empty.$<COMPILE_LANGUAGE>)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-stderr.txt
new file mode 100644
index 0000000..c9ee6fe
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-add_library.cmake:4 \(add_library\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library.cmake
new file mode 100644
index 0000000..dd9f824
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_library.cmake
@@ -0,0 +1,4 @@
+
+enable_language(C)
+
+add_library(empty empty.$<COMPILE_LANGUAGE>)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-stderr.txt
new file mode 100644
index 0000000..9955f5d
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-add_test.cmake:5 \(add_test\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test.cmake
new file mode 100644
index 0000000..deedf65
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-add_test.cmake
@@ -0,0 +1,5 @@
+
+include(CTest)
+enable_testing()
+
+add_test(NAME dummy COMMAND ${CMAKE_COMMAND} -E echo $<COMPILE_LANGUAGE>)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-stderr.txt
new file mode 100644
index 0000000..eca700f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install-stderr.txt
@@ -0,0 +1,8 @@
+CMake Error:
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install.cmake
new file mode 100644
index 0000000..92c20e3
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-install.cmake
@@ -0,0 +1,5 @@
+
+install(FILES
+  empty.$<COMPILE_LANGUAGE>
+  DESTINATION src
+)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-stderr.txt
new file mode 100644
index 0000000..2d324e2
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources-stderr.txt
@@ -0,0 +1,10 @@
+CMake Error at COMPILE_LANGUAGE-target_sources.cmake:5 \(target_sources\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE>
+
+  \$<COMPILE_LANGUAGE:...> may only be used to specify include directories
+  compile definitions, compile options and to evaluate components of the
+  file\(GENERATE\) command.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources.cmake
new file mode 100644
index 0000000..0c78acd
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-target_sources.cmake
@@ -0,0 +1,5 @@
+
+enable_language(C)
+
+add_library(empty empty.c)
+target_sources(empty PRIVATE empty.$<COMPILE_LANGUAGE>)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-result.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-result.txt
new file mode 100644
index 0000000..d00491f
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-result.txt
@@ -0,0 +1 @@
+1
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-stderr.txt b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-stderr.txt
new file mode 100644
index 0000000..444da45
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang-stderr.txt
@@ -0,0 +1,8 @@
+CMake Error at COMPILE_LANGUAGE-unknown-lang.cmake:4 \(target_compile_options\):
+  Error evaluating generator expression:
+
+    \$<COMPILE_LANGUAGE:CXX>
+
+  \$<COMPILE_LANGUAGE:...> Unknown language.
+Call Stack \(most recent call first\):
+  CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang.cmake b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang.cmake
new file mode 100644
index 0000000..cec12a3
--- /dev/null
+++ b/Tests/RunCMake/GeneratorExpression/COMPILE_LANGUAGE-unknown-lang.cmake
@@ -0,0 +1,4 @@
+
+enable_language(C)
+add_executable(empty empty.c)
+target_compile_options(empty PRIVATE $<$<COMPILE_LANGUAGE:CXX>:-Wall>)
diff --git a/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake b/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
index 6c32393..542b7fc 100644
--- a/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
+++ b/Tests/RunCMake/GeneratorExpression/RunCMakeTest.cmake
@@ -16,6 +16,14 @@ run_cmake(NonValidTarget-C_COMPILER_VERSION)
 run_cmake(NonValidTarget-CXX_COMPILER_VERSION)
 run_cmake(NonValidTarget-TARGET_PROPERTY)
 run_cmake(NonValidTarget-TARGET_POLICY)
+run_cmake(COMPILE_LANGUAGE-add_custom_target)
+run_cmake(COMPILE_LANGUAGE-add_custom_command)
+run_cmake(COMPILE_LANGUAGE-install)
+run_cmake(COMPILE_LANGUAGE-target_sources)
+run_cmake(COMPILE_LANGUAGE-add_executable)
+run_cmake(COMPILE_LANGUAGE-add_library)
+run_cmake(COMPILE_LANGUAGE-add_test)
+run_cmake(COMPILE_LANGUAGE-unknown-lang)
 
 if(LINKER_SUPPORTS_PDB)
   run_cmake(NonValidTarget-TARGET_PDB_FILE)