Teach target_* commands to set INTERFACE properties of IMPORTED targets

Now, several `INTERFACE_*` properties can be set on `IMPORTED` targets,
not only via `set_property` and `set_target_properties` but also via
`target_compile_definitions`, `target_compile_features`,
`target_compile_options`, `target_include_directories`, `target_sources`
and `target_link_libraries`.

Fixes: #15689
Issue: #17197

Tests/RunCMake/add_library/UNKNOWNwithNoSourcesButLinkObjects-stderr.txt

@@ -1,5 +0,0 @@
-^CMake Error at UNKNOWNwithNoSourcesButLinkObjects.cmake:[0-9]+ \(target_link_libraries\):
-  Cannot specify link libraries for target \"TestUnknownLibWithoutSources\"
-  which is not built by this project.
-Call Stack \(most recent call first\):
-  CMakeLists.txt:[0-9]+ \(include\)$

Tests/RunCMake/add_library/UNKNOWNwithNoSourcesButLinkObjects.cmake

@@ -2,4 +2,4 @@ enable_language(CXX)
 add_library(ObjectLibDependency OBJECT test.cpp)
 
 add_library(TestUnknownLibWithoutSources UNKNOWN IMPORTED)
-target_link_libraries(TestUnknownLibWithoutSources PUBLIC $<TARGET_OBJECTS:ObjectLibDependency>)
+target_link_libraries(TestUnknownLibWithoutSources INTERFACE $<TARGET_OBJECTS:ObjectLibDependency>)

Tests/RunCMake/target_compile_features/imported_target-stderr.txt

@@ -1,4 +1,5 @@
-CMake Error at imported_target.cmake:[0-9]+ \(target_compile_features\):
-  Cannot specify compile features for imported target "main".
+^CMake Error at imported_target.cmake:[0-9]+ \(target_compile_features\):
+  target_compile_features may only set INTERFACE properties on INTERFACE
+  targets
 Call Stack \(most recent call first\):
-  CMakeLists.txt:3 \(include\)
+  CMakeLists.txt:3 \(include\)$

Tests/RunCMake/target_compile_features/imported_target.cmake

@@ -1,4 +1,10 @@
 enable_language(CXX)
 
-add_library(main INTERFACE IMPORTED)
-target_compile_features(main INTERFACE cxx_delegating_constructors)
+add_library(lib1-interface INTERFACE IMPORTED)
+target_compile_features(lib1-interface INTERFACE cxx_delegating_constructors)
+
+add_library(lib2-interface INTERFACE IMPORTED)
+target_compile_features(lib2-interface PUBLIC cxx_delegating_constructors)
+
+add_library(lib-shared SHARED IMPORTED)
+target_compile_features(lib-shared INTERFACE cxx_delegating_constructors)

Tests/RunCMake/target_link_libraries/ImportedTarget.cmake

@@ -0,0 +1,2 @@
+add_library(UnknownImportedGlobal UNKNOWN IMPORTED GLOBAL)
+target_link_libraries(UnknownImportedGlobal INTERFACE z)

Tests/RunCMake/target_link_libraries/ImportedTargetFailure-stderr.txt

@@ -0,0 +1,5 @@
+^CMake Error at ImportedTargetFailure.cmake:[0-9]+ \(target_link_libraries\):
+  IMPORTED library can only be used with the INTERFACE keyword of
+  target_link_libraries
+Call Stack \(most recent call first\):
+  CMakeLists\.txt:[0-9]+ \(include\)$

Tests/RunCMake/target_link_libraries/ImportedTargetFailure.cmake

@@ -0,0 +1,2 @@
+add_library(UnknownImportedGlobal UNKNOWN IMPORTED GLOBAL)
+target_link_libraries(UnknownImportedGlobal PRIVATE z)

Tests/RunCMake/target_link_libraries/RunCMakeTest.cmake

@@ -4,6 +4,8 @@ run_cmake(CMP0023-WARN)
 run_cmake(CMP0023-NEW)
 run_cmake(CMP0023-WARN-2)
 run_cmake(CMP0023-NEW-2)
+run_cmake(ImportedTarget)
+run_cmake(ImportedTargetFailure)
 run_cmake(MixedSignature)
 run_cmake(Separate-PRIVATE-LINK_PRIVATE-uses)
 run_cmake(SubDirTarget)