Add $<LINK_LANGUAGE> generator expression

They can't be used when evaluating link libraries, but they can be
used for include directories and compile definitions. Later they can
be used for compile options.

5 files changed, 92 insertions, 0 deletions

diff --git a/Tests/CompileDefinitions/compiletest.c b/Tests/CompileDefinitions/compiletest.c
new file mode 100644
index 0000000000..d7883af77d
--- /dev/null
+++ b/Tests/CompileDefinitions/compiletest.c
@@ -0,0 +1,19 @@
+
+#ifndef LINK_C_DEFINE
+#error Expected LINK_C_DEFINE
+#endif
+#ifndef LINK_LANGUAGE_IS_C
+#error Expected LINK_LANGUAGE_IS_C
+#endif
+
+#ifdef LINK_CXX_DEFINE
+#error Unexpected LINK_CXX_DEFINE
+#endif
+#ifdef LINK_LANGUAGE_IS_CXX
+#error Unexpected LINK_LANGUAGE_IS_CXX
+#endif
+
+int main(void)
+{
+  return 0;
+}
diff --git a/Tests/CompileDefinitions/compiletest.cpp b/Tests/CompileDefinitions/compiletest.cpp
index 7379380dec..7df09df819 100644
--- a/Tests/CompileDefinitions/compiletest.cpp
+++ b/Tests/CompileDefinitions/compiletest.cpp
@@ -56,6 +56,21 @@ enum {
 #error Expect PREFIX_DEF2
 #endif
 
+#ifndef LINK_CXX_DEFINE
+#error Expected LINK_CXX_DEFINE
+#endif
+#ifndef LINK_LANGUAGE_IS_CXX
+#error Expected LINK_LANGUAGE_IS_CXX
+#endif
+
+#ifdef LINK_C_DEFINE
+#error Unexpected LINK_C_DEFINE
+#endif
+#ifdef LINK_LANGUAGE_IS_C
+#error Unexpected LINK_LANGUAGE_IS_C
+#endif
+
+
 // TEST_GENERATOR_EXPRESSIONS
 #endif
 
diff --git a/Tests/CompileDefinitions/compiletest_mixed_c.c b/Tests/CompileDefinitions/compiletest_mixed_c.c
new file mode 100644
index 0000000000..698c989a81
--- /dev/null
+++ b/Tests/CompileDefinitions/compiletest_mixed_c.c
@@ -0,0 +1,19 @@
+
+#ifndef LINK_CXX_DEFINE
+#error Expected LINK_CXX_DEFINE
+#endif
+#ifndef LINK_LANGUAGE_IS_CXX
+#error Expected LINK_LANGUAGE_IS_CXX
+#endif
+
+#ifdef LINK_C_DEFINE
+#error Unexpected LINK_C_DEFINE
+#endif
+#ifdef LINK_LANGUAGE_IS_C
+#error Unexpected LINK_LANGUAGE_IS_C
+#endif
+
+void someFunc(void)
+{
+
+}
diff --git a/Tests/CompileDefinitions/compiletest_mixed_cxx.cpp b/Tests/CompileDefinitions/compiletest_mixed_cxx.cpp
new file mode 100644
index 0000000000..c6868547de
--- /dev/null
+++ b/Tests/CompileDefinitions/compiletest_mixed_cxx.cpp
@@ -0,0 +1,19 @@
+
+#ifndef LINK_CXX_DEFINE
+#error Expected LINK_CXX_DEFINE
+#endif
+#ifndef LINK_LANGUAGE_IS_CXX
+#error Expected LINK_LANGUAGE_IS_CXX
+#endif
+
+#ifdef LINK_C_DEFINE
+#error Unexpected LINK_C_DEFINE
+#endif
+#ifdef LINK_LANGUAGE_IS_C
+#error Unexpected LINK_LANGUAGE_IS_C
+#endif
+
+int main(int argc, char **argv)
+{
+  return 0;
+}
diff --git a/Tests/CompileDefinitions/target_prop/CMakeLists.txt b/Tests/CompileDefinitions/target_prop/CMakeLists.txt
index 34be91779c..66a3aa65e4 100644
--- a/Tests/CompileDefinitions/target_prop/CMakeLists.txt
+++ b/Tests/CompileDefinitions/target_prop/CMakeLists.txt
@@ -19,9 +19,29 @@ set_property(TARGET target_prop_executable APPEND PROPERTY COMPILE_DEFINITIONS
     LETTER_LIST3=\"$<JOIN:A;B;C;D,,->\"
     LETTER_LIST4=\"$<JOIN:A;B;C;D,-,->\"
     LETTER_LIST5=\"$<JOIN:A;B;C;D,-,>\"
+    "$<$<LINK_LANGUAGE:CXX>:LINK_CXX_DEFINE>"
+    "$<$<LINK_LANGUAGE:C>:LINK_C_DEFINE>"
+    "LINK_LANGUAGE_IS_$<LINK_LANGUAGE>"
 )
 
 set_property(TARGET target_prop_executable APPEND PROPERTY COMPILE_DEFINITIONS
   BUILD_IS_DEBUG=$<CONFIG:Debug>
   BUILD_IS_NOT_DEBUG=$<NOT:$<CONFIG:Debug>>
   )
+
+add_executable(target_prop_c_executable ../compiletest.c)
+
+set_property(TARGET target_prop_c_executable APPEND PROPERTY COMPILE_DEFINITIONS
+    "$<$<LINK_LANGUAGE:CXX>:LINK_CXX_DEFINE>"
+    "$<$<LINK_LANGUAGE:C>:LINK_C_DEFINE>"
+    "LINK_LANGUAGE_IS_$<LINK_LANGUAGE>"
+    )
+
+# Resulting link language will be CXX
+add_executable(target_prop_mixed_executable ../compiletest_mixed_c.c ../compiletest_mixed_cxx.cpp)
+
+set_property(TARGET target_prop_mixed_executable APPEND PROPERTY COMPILE_DEFINITIONS
+    "$<$<LINK_LANGUAGE:CXX>:LINK_CXX_DEFINE>"
+    "$<$<LINK_LANGUAGE:C>:LINK_C_DEFINE>"
+    "LINK_LANGUAGE_IS_$<LINK_LANGUAGE>"
+    )