[llvm-dev] change in CMake variable names breaks existing uses and does not conform to CMake conventions

[Mueller-Roemer, Johannes Sebastian via llvm-dev]

Hi Philip,

thanks for the hint about the man page. Totally forgot about that.

Even though Config-mode generally has different rules, we don’t truly support that anyways as none of the exported targets have the INTERFACE_INCLUDE_DIRECTORIES (in which case the LLVM_INCLUDE_DIRS variable would become unnecessary anyways).

Regards,
Johannes

From: Philip Pfaffe [mailto:philip.pfaffe at gmail.com]
Sent: Thursday, September 1, 2016 14:01
To: Mueller-Roemer, Johannes Sebastian <Johannes.Sebastian.Mueller-Roemer at igd.fraunhofer.de>
Cc: Chris Bieneman (cbieneman at apple.com) <cbieneman at apple.com>; llvm-dev at lists.llvm.org
Subject: Re: [llvm-dev] change in CMake variable names breaks existing uses and does not conform to CMake conventions

Hi Everyone, (resending because I can't get the hang of Reply All)

I second Johannes.

cmake's own Find* man page suggests using the _DIRS variant "to keep things consistent":
https://cmake.org/cmake/help/git-master/manual/cmake-developer.7.html#standard-variable-names

Granted, we're supporting Config-mode and not Module-mode, but i think the variable name rules should still apply for consistency.

Best
Philip

2016-09-01 13:31 GMT+02:00 Mueller-Roemer, Johannes Sebastian via llvm-dev <llvm-dev at lists.llvm.org<mailto:llvm-dev at lists.llvm.org>>:
Hi Chris and everyone else,

I just noticed that some of my builds broke due to commit 280013, as LLVM_INCLUDE_DIRS was renamed to LLVM_INCLUDE_DIR. In and of itself, not much of an issue as the fix is just to remove one character (in a couple of places). However, I would like to discuss if this rename is desirable at all. Sure, in-tree LLVM_INCLUDE_DIR is used everywhere, however not providing an ${NAME}_INCLUDE_DIRS variable goes against CMake conventions. See for example the find scripts included with CMake itself:

https://cmake.org/cmake/help/v3.6/module/FindZLIB.html -> provides ZLIB_INCLUDE_DIRS (and not ZLIB_INCLUDE_DIR) even though it is typically only one directory

And the same holds true for most  other Find${NAME}.cmake scripts I had a look at (Boost, Bullet, CUDA, Freetype, XMLRPC, Zlib). I’ll admit there are 1 or 2 exceptions (such as OpenGL) but in general I think it would be better to stick to the more common/conventional case.

Thoughts?

Regards
Johannes


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