add_library: Allow arbitrary non-linked sources in OBJECT libraries

Loosen this restriction on OBJECT libraries to allow source files of any
name to be generated by custom commands or listed for reference in IDE
projects so long as they would not affect linking of a normal library.
Update the rejection message to be more specific about the looser
restriction.

Extend the ObjectLibrary test to cover a ".cmake" file generated by a
custom command in an OBJECT library.

4 files changed, 17 insertions, 3 deletions

diff --git a/Tests/ObjectLibrary/A/CMakeLists.txt b/Tests/ObjectLibrary/A/CMakeLists.txt
index 3fba9f8..c24c5ed 100644
--- a/Tests/ObjectLibrary/A/CMakeLists.txt
+++ b/Tests/ObjectLibrary/A/CMakeLists.txt
@@ -11,5 +11,16 @@ add_custom_command(
                                    ${CMAKE_CURRENT_BINARY_DIR}/a1.c
   )
 
-add_library(A OBJECT a1.c a2.c)
+# Remove the custom command output to be sure it runs in an
+# incremental test.  Skip this on VS 6 because it sometimes
+# re-runs CMake after the custom command runs.
+if(NOT CMAKE_GENERATOR STREQUAL "Visual Studio 6")
+  file(REMOVE ${CMAKE_CURRENT_BINARY_DIR}/a.cmake)
+endif()
+add_custom_command(
+  OUTPUT a.cmake
+  COMMAND ${CMAKE_COMMAND} -E touch ${CMAKE_CURRENT_BINARY_DIR}/a.cmake
+  )
+
+add_library(A OBJECT a1.c a2.c a.cmake)
 target_include_directories(A PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
diff --git a/Tests/ObjectLibrary/CMakeLists.txt b/Tests/ObjectLibrary/CMakeLists.txt
index 75c34d8..e9f553e 100644
--- a/Tests/ObjectLibrary/CMakeLists.txt
+++ b/Tests/ObjectLibrary/CMakeLists.txt
@@ -12,6 +12,7 @@ add_library(Cshared SHARED c.c $<TARGET_OBJECTS:A> $<TARGET_OBJECTS:Bexport>)
 add_executable(UseCshared main.c)
 set_property(TARGET UseCshared PROPERTY COMPILE_DEFINITIONS SHARED_C)
 target_link_libraries(UseCshared Cshared)
+add_custom_command(TARGET UseCshared POST_BUILD COMMAND ${CMAKE_COMMAND} -P ${CMAKE_CURRENT_BINARY_DIR}/A/a.cmake)
 
 add_executable(UseCinternal main.c c.c $<TARGET_OBJECTS:A> $<TARGET_OBJECTS:B>)
 
diff --git a/Tests/RunCMake/ObjectLibrary/BadObjSource1-stderr.txt b/Tests/RunCMake/ObjectLibrary/BadObjSource1-stderr.txt
index b31225b..a09552b 100644
--- a/Tests/RunCMake/ObjectLibrary/BadObjSource1-stderr.txt
+++ b/Tests/RunCMake/ObjectLibrary/BadObjSource1-stderr.txt
@@ -3,6 +3,7 @@ CMake Error at BadObjSource1.cmake:1 \(add_library\):
 
     bad.def
 
-  but may contain only headers and sources that compile.
+  but may contain only sources that compile, header files, and other files
+  that would not affect linking of a normal library.
 Call Stack \(most recent call first\):
   CMakeLists.txt:3 \(include\)
diff --git a/Tests/RunCMake/ObjectLibrary/BadObjSource2-stderr.txt b/Tests/RunCMake/ObjectLibrary/BadObjSource2-stderr.txt
index 906cf0b..b91ffd0 100644
--- a/Tests/RunCMake/ObjectLibrary/BadObjSource2-stderr.txt
+++ b/Tests/RunCMake/ObjectLibrary/BadObjSource2-stderr.txt
@@ -3,6 +3,7 @@ CMake Error at BadObjSource2.cmake:1 \(add_library\):
 
     bad.obj
 
-  but may contain only headers and sources that compile.
+  but may contain only sources that compile, header files, and other files
+  that would not affect linking of a normal library.
 Call Stack \(most recent call first\):
   CMakeLists.txt:3 \(include\)