# How to generate depends.make file for custom language

**URL:** <https://discourse.cmake.org/t/how-to-generate-depends-make-file-for-custom-language/2173>\
**Category:** Code\
**Tags:** gen:makefiles\
**Created:** [November 13, 2020, 11:25pm UTC](https://discourse.cmake.org/t/how-to-generate-depends-make-file-for-custom-language/2173 "2020-11-13T23:25:12Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rjenkins](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/r/eada6e/32.png) [@rjenkins](https://discourse.cmake.org/u/rjenkins)\
**Post date:** [November 13, 2020, 11:25pm UTC](https://discourse.cmake.org/t/how-to-generate-depends-make-file-for-custom-language/2173/1 "2020-11-13T23:25:12Z")

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Hello,  
I am trying to make a custom language option for building cmake, but my compilation does not correctly update when I do a touch on a header file.  
In older versions of cmake I remember using (with c++ compilers) something along the lines of

```auto
CMAKE_DEPFILE_FLAGS_<LANGUAGE> "-MD -MT <OBJECT> -MF <DEPFILE>"

```

But now it looks like dependencies are aggregated into a depend.make at configuration? Can someone point me in the right direction?

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**Author:** ![marc.chevrier](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/m/ecb155/32.png) [@marc.chevrier](https://discourse.cmake.org/u/marc.chevrier)\
**Post date:** [November 14, 2020, 9:23am UTC](https://discourse.cmake.org/t/how-to-generate-depends-make-file-for-custom-language/2173/2 "2020-11-14T09:23:19Z")

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`CMAKE_DEPFILE_FLAGS_...` is only used by `Ninja` generators. `Makefiles` generators rely on `CMake` internal parser which generates `depend.make` file.  
Unfortunately, this internal parser cannot be customized so custom languages cannot benefit from this parser.

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<div class="post-metadata">

**Author:** ![rjenkins](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/r/eada6e/32.png) [@rjenkins](https://discourse.cmake.org/u/rjenkins)\
**Post date:** [November 29, 2020, 6:02am UTC](https://discourse.cmake.org/t/how-to-generate-depends-make-file-for-custom-language/2173/3 "2020-11-29T06:02:00Z")

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In case anyone is interested, I switched over to the ninja generator and the dependency generation worked (I was compiling to llvm-ir and doing extra compilation passes followed by full LTO).

Thanks for the help Marc!