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IDProjectCategoryView StatusDate SubmittedLast Update
0011985CMakeCMakepublic2011-03-18 10:132016-06-10 14:31
ReporterMathias Gaunard 
Assigned ToKitware Robot 
PrioritynormalSeverityminorReproducibilityalways
StatusclosedResolutionmoved 
PlatformAnyOSOS Version
Product VersionCMake-2-8 
Target VersionFixed in Version 
Summary0011985: CMake scanner doesn't extract dependencies of C and C++ files correctly
DescriptionDue to using a simplified scanner that doesn't do full preprocessing, include directives that depend on C/C++ preprocessor usage are not dealt with correctly.

This has been discussed on the mailing list here:
http://www.cmake.org/pipermail/cmake/2010-July/038465.html [^]

CMake should detect when files contain non-trivial include directives and invoke a full C preprocessor in that case.

Alternatively CMake could provide a way to override the tool used to detect those dependencies.
Indeed, in the current situation, there seems to be no workaround possible. Explicitly adding OBJECT_DEPENDS properties doesn't seem to work either.
Steps To ReproduceDownload attached testcase.
Run cmake with the Makefile or NMakefile generator.
Make the 'test' target.
Touch test2.hpp to make it more recent
Make the 'test' target again, and notice nothing gets recompiled
Additional InformationHaving correct dependencies of C/C++ files is extremely important, especially for continuous integration solutions.

Such includes exist in various libraries. The Boost C++ libraries contain such includes to generate its meta-programming code, while several other libraries use such includes to conditionally include code for one architecture or another.
TagsNo tags attached.
Attached Filesbz2 file icon test_cmake.tar.bz2 [^] (431 bytes) 2011-03-18 10:13

 Relationships
related to 0013718closedKitware Robot CMake does not preprocess out conditional includes while scanning dependencies 

  Notes
(0025805)
Mathias Gaunard (reporter)
2011-03-18 10:18

 Sorry, should be "CMake scanner doesn't extract dependencies of C and C++ files correctly".
Can't find how to update the summary.
(0025806)
Michael Wild (reporter)
2011-03-18 10:33

 Just a crazy idea, but couldn't CMake use the clang libraries (libbasic and liblex should do the trick AFAIK) to do actual, correct preprocessing? The clang license is a BSD-variant, and should be compatible with the one used by CMake, so the sources could actually be included in CMake...
(0025828)
Mathias Gaunard (reporter)
2011-03-19 09:19

 Beware with using the clang libraries.
To have the correct dependencies, the preprocessor would need to behave exactly like the target compiler: have all the same macros predefined, and more importantly exhibit the same preprocessing bugs.
(0025833)
Michael Wild (reporter)
2011-03-19 11:09

 True. Didn't think of that. There are two other options I can see which don't suffer from above mentioned problems:

- Ask the compiler to come up with a list of dependencies (e.g. "gcc -M"). This is problematic at best for some tool chains (e.g. requires quite some work with MS compilers), sometimes it's also unbelievably slow.

- Use LD_PRELOAD/DLL-injection to track all files opened by the compiler during compilation (take a look at Tup for an example). While potentially very complete (also handles other files, such as compiler configuration files, libraries etc.) it makes my skin crawl...
(0031624)
Mathias Gaunard (reporter)
2012-11-20 10:43

 The Ninja generator uses gcc -M for gcc and a special tool for MSVC, and is therefore not affected by this bug.
Other generators could be changed to behave like the Ninja generator.
(0041822)
Kitware Robot (administrator)
2016-06-10 14:28

 Resolving issue as `moved`.

This issue tracker is no longer used. Further discussion of this issue may take place in the current CMake Issues page linked in the banner at the top of this page.

 Issue History
Date Modified Username Field Change
2011-03-18 10:13 Mathias Gaunard New Issue
2011-03-18 10:13 Mathias Gaunard File Added: test_cmake.tar.bz2
2011-03-18 10:18 Mathias Gaunard Note Added: 0025805
2011-03-18 10:33 Michael Wild Note Added: 0025806
2011-03-19 09:19 Mathias Gaunard Note Added: 0025828
2011-03-19 11:09 Michael Wild Note Added: 0025833
2011-03-29 18:02 Brad King Status new => backlog
2012-11-20 09:27 Brad King Relationship added related to 0013718
2012-11-20 10:43 Mathias Gaunard Note Added: 0031624
2013-01-05 03:00 Peter Kuemmel Summary CMake scanner does extract dependencies of C and C++ files correctly => CMake scanner doesn't extract dependencies of C and C++ files correctly
2016-06-10 14:28 Kitware Robot Note Added: 0041822
2016-06-10 14:28 Kitware Robot Status backlog => resolved
2016-06-10 14:28 Kitware Robot Resolution open => moved
2016-06-10 14:28 Kitware Robot Assigned To => Kitware Robot
2016-06-10 14:31 Kitware Robot Status resolved => closed

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