Commit v3.1.0-rc1~297^2~5 (cmTarget: Drop 'head' argument from
GetSourceFiles, 2014-07-10) exposed a dormant bug in source file computation,
causing the test case to regress. After that commit, the source file
computation and caching finds an existing container of source files. Prior to
that patch, the GetSourceFiles method was called with either a null pointer
for the head cmTarget, or it was called with the this pointer. The
processSources method is eventually called, which normalizes the difference
between the null pointer and the this pointer for the head target. However,
the cache key depends on the actual pre-normalized pointer. The change in
that commit caused the entry to be found in the cache where it was not before,
which resulted in incorrect behavior.
Prior to that commit, the test case also fails if the GetSourceFiles overload
taking a vector<cmSourceFile*> is changed to normalize the head target at
the beginning of the method:
cmTarget const* head = head_ ? head_ : this;
Such a construct was correctly used in other locations where similar caching
was in place, before being removed in commit v3.1.0-rc1~310^2~25 (cmTarget:
Remove 'head' argument from GetLinkInformation, 2014-06-12), but is not
neccessary anymore.
Commit v3.1.0-rc1~674^2~2 (cmTarget: Cache the cmSourceFiles in
GetSourceFiles., 2014-04-05) introduced the caching, but fails the test case
for an unrelated reason. That unrelated error was introduced in
commit v3.1.0-rc1~688^2~5 (cmTarget: Allow any generator expression in
SOURCES property., 2014-03-18) and fixed in
commit v3.1.0-rc1~561^2~1 (cmTarget: Fix listing of source files at
configure-time., 2014-04-13).
All commits which fail the test case in the testable way do so when such a
cached version of the source files is found and returned at generate
time. In the test case, the cached content is populated at configure-time
through the use of the deprecated LOCATION property with CMP0026 OLD. The
cached content is an empty container for the bar target in the test case,
because its source file 'foo.cpp.o' is not known until generate-time. That
means that no source files are available to compute the link language and
the reported error is issued.
The actual problem is that the SourceFilesMap should be cleared after
configure time by cmTarget::ClearLinkMaps. Clear it there now.
If you think about adding a new testcase then here is a small checklist you
can run through to find a proper place for it. Go through the list from the
beginning and stop once you find something that matches your tests needs,
i.e. if you will test a module and only need the configure mode use the
instructions from section 2, not 3.
1. Your testcase can run in CMake script mode, i.e. "cmake -P something"
Put your test in Tests/CMakeTests/ directory as a .cmake.in file. It will be
put into the test binary directory by configure_file(... @ONLY) and run from
there. Use the AddCMakeTest() macro in Tests/CMakeTests/CMakeLists.txt to add
your test to the test runs.
2. Your test needs CMake to run in configure mode, but will not build anything
This includes tests that will build something using try_compile() and friends,
but nothing that expects add_executable(), add_library(), or add_test() to run.
If the test configures the project only once and it must succeed then put it
into the Tests/CMakeOnly/ directory. Create a subdirectory named like your
test and write the CMakeLists.txt you need into that subdirectory. Use the
add_CMakeOnly_test() macro from Tests/CMakeOnly/CMakeLists.txt to add your
test to the test runs.
If the test configures the project with multiple variations and verifies
success or failure each time then put it into the Tests/RunCMake/ directory.
Read the instructions in Tests/RunCMake/CMakeLists.txt to add a test.
3. If you are testing something from the Modules directory
Put your test in the Tests/Modules/ directory. Create a subdirectory there
named after your test. Use the ADD_TEST_MACRO macro from Tests/CMakeLists.txt
to add your test to the test run. If you have put your stuff in
Tests/Modules/Foo then you call it using ADD_TEST_MACRO(Module.Foo Foo).
4. You are doing other stuff.
Find a good place ;) In doubt mail to cmake-developers@cmake.org and ask for
advise.
23f3798c7b