[cmake-developers] linked-usage-cleanup regressed automoc

[Alexander Neundorf]

Hi,

On Wednesday 20 February 2013, Stephen Kelly wrote:
> Alexander Neundorf wrote:
> > On Wednesday 20 February 2013, Stephen Kelly wrote:
> >> Brad King wrote:
> >> > Please fix and add this case to the tests.
> >> 
> >> I've added fix-automoc-linker-language to stage. Alex, could you review
> >> please?
> > 
> > If I see it correctly, actually nothing is done to each target between
> > the calls to InitializeMocSourceFile() and the following
> > SetupAutomocTarget(). So instead of running two loops over the targets,
> > shouldn't it be enough to add the source file to the target early on in
> > SetupAutomocTarget(), e.g. before the call to AddUtilityCommand() ?
> 
> I tried that too, but the problem is that if two different targets are
> dependent, it seems that the link closure is calculated and cached for the
> dependent target before it gets its source file set.
> 
> There are a few ways to deal with that, but I went with this one.
> 
> I'll merge it soon. Thanks for reviewing.

Unfortunately this patch creates bug ( 
http://public.kitware.com/Bug/view.php?id=13999 ) and doesn't fix the actual 
problem, the crash is still there.

Before this patch, void cmQtAutomoc::SetupAutomocTarget(cmTarget* target) 
returned early if no Qt was present, and nothing bad happened in this case.

With this patch, the <target>_automoc.cpp file is added to every target.
Probably this fixes the original problem because now the target 
"no_link_language" has a link language, due to its newly attached source file 
no_link_language_automoc.cpp.
It then crashes:

CMake Error: CMake can not determine linker language for 
target:no_link_language

Program received signal SIGSEGV, Segmentation fault.
0x082d55a3 in std::vector<cmComputeLinkInformation::Item, 
std::allocator<cmComputeLinkInformation::Item> >::begin() const ()
(gdb) bt
#0  0x082d55a3 in std::vector<cmComputeLinkInformation::Item, 
std::allocator<cmComputeLinkInformation::Item> >::begin() const ()
#1  0x082cc76d in isLinkDependentProperty(cmTarget*, std::basic_string<char, 
std::char_traits<char>, std::allocator<char> > const&, char const*, char 
const*) ()
#2  0x082cc98d in 
cmTarget::IsLinkInterfaceDependentBoolProperty(std::basic_string<char, 
std::char_traits<char>, std::allocator<char> > const&, char const*) ()
#3  0x083d9b8c in 
TargetPropertyNode::Evaluate(std::vector<std::basic_string<char, 
std::char_traits<char>, std::allocator<char> >, 
std::allocator<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> > > > const&, cmGeneratorExpressionContext*, 
GeneratorExpressionContent const*, cmGeneratorExpressionDAGChecker*) const ()
#4  0x083d6b53 in 
GeneratorExpressionContent::Evaluate(cmGeneratorExpressionContext*, 
cmGeneratorExpressionDAGChecker*) const ()
#5  0x083de544 in cmCompiledGeneratorExpression::Evaluate(cmMakefile*, char 
const*, bool, cmTarget*, cmTarget*, cmGeneratorExpressionDAGChecker*) const ()
#6  0x083de438 in cmCompiledGeneratorExpression::Evaluate(cmMakefile*, char 
const*, bool, cmTarget*, cmGeneratorExpressionDAGChecker*) const ()
#7  0x082c4cc1 in processIncludeDirectories(cmTarget*, 
std::vector<cmTargetInternals::IncludeDirectoriesEntry*, 
std::allocator<cmTargetInternals::IncludeDirectoriesEntry*> > const&, 
std::vector<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> >, std::allocator<std::basic_string<char, 
std::char_traits<char>, std::allocator<char> > > >&, 
std::set<std::basic_string<char, std::char_traits<char>, std::allocator<char> 
>, std::less<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> > >, std::allocator<std::basic_string<char, 
std::char_traits<char>, std::allocator<char> > > >&, 
cmGeneratorExpressionDAGChecker*, char const*, bool) ()
#8  0x082c5895 in cmTarget::GetIncludeDirectories(char const*) ()
#9  0x083e0e86 in cmGeneratorTarget::GetIncludeDirectories(char const*) ()
#10 0x08413808 in 
cmLocalGenerator::GetIncludeDirectories(std::vector<std::basic_string<char, 
std::char_traits<char>, std::allocator<char> >, 
std::allocator<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> > > >&, cmGeneratorTarget*, char const*, char const*, 
bool) ()
#11 0x0844b611 in cmQtAutomoc::SetupAutomocTarget(cmTarget*) ()
#12 0x083e66fe in cmGlobalGenerator::CreateAutomocTargets() ()
#13 0x083e5e7f in cmGlobalGenerator::Generate() ()
#14 0x083f8ffe in cmGlobalUnixMakefileGenerator3::Generate() ()
#15 0x082f0cbe in cmake::Generate() ()
#16 0x082f0b01 in cmake::Run(std::vector<std::basic_string<char, 
std::char_traits<char>, std::allocator<char> >, 
std::allocator<std::basic_string<char, std::char_traits<char>, 
std::allocator<char> > > > const&, bool) ()
#17 0x08257b41 in do_cmake(int, char**) ()
#18 0x08257099 in main ()
(gdb) 


(this is again the backtrace from the earlier, unmodified version).
I think instead of avoiding the case where the code crashes, it should not 
crash.

I pushed the branch AutomocFixWithoutQt to stage.
It mostly reverts the previous change.
Additionally it adds a test for the case that there is no Qt, and it adds 
handling for the case that a target does not contain any C++ files (it now 
does nothing).

The crash can be also reproduced with the attached example, completely without 
Qt and/or automoc.

If you want I can enter a ticket for that.

Alex
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