40 lines
2.3 KiB
Markdown
40 lines
2.3 KiB
Markdown
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---
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title: "CMake & Meson & CompCert"
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date: 2020-06-07T16:13:00+02:00
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draft: false
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categories: [c, development]
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tags: [c]
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url: /posts/cmake-meson-compcert/
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author: "Christoph Cullmann"
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---
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I tried to compile the [Picolibc](https://github.com/keith-packard/picolibc) that uses the [Meson build system](https://mesonbuild.com/) with [CompCert](http://compcert.inria.fr/).
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The CompCert install I tried uses the GNU/GCC toolchain for preprocessing and linking.
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That makes the compiler relatively compatible to a GCC, beside that not all command line options are supported.
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I was used to [CMake](https://www.cmake.org) projects and there it is normally enough to just set CC=ccomp and you are ready and set (at least if you use the GNU/GCC toolchain).
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As long as you don't use special flags in your project, that will just work.
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The Picolibc was the first Meson based project I encountered.
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There setting CC to ccomp just leads to
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{{< highlight bash >}}
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meson.build:1:0: ERROR: Unknown compiler(s): [['ccomp']]
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{{< / highlight >}}
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I did assume that the project won't compile & link without adjustments, as CompCert doesn't support the full range of command line options like GCC as mentioned above nor the full GNU extensions for C.
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But that it directly ends at the compiler initialization in the build system itself was astonishing.
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I searched a bit in the internet and it seems, if I really want to get this working, I actually need to patch Meson itself :/
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(see how to add a new compiler [here](https://github.com/mesonbuild/meson/commit/74602928100394f6129e064f8e0bfe6c9e08c9d2#diff-1eaa302b42bbbba32f1c6d474d08397e)
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At least I found no other solution, actually, I found no real solution for the above error message at all and the code looks like you need to manually add compilers anyways.
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Given I want to spend work on getting the C library to compile and not fix a build system, it seems easier to go with the [newlib](https://github.com/mirror/newlib-cygwin) that uses the old autotools,
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at least for them the compile starts at all with my CC environment variable and you get to places of interest to fix.
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This means for my use case, with a non-standard compiler, I can not see how Meson is an improvement over other existing stuff like CMake or even autotools.
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But perhaps this area will improve in the future.
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