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It seems that C developers tend to use Turing-complete scripts for building instead of a declarative language. Using scripts means that build configuration cann

It seems that C developers tend to use Turing-complete scripts for building instead of a declarative language. Using scripts means that build configuration cannot be processed by automated tools for extraction of information or modification. Why don't you want to use declarative build configuration?

GrantMoyer 2y ago
In my experience the short answer is that there are no declarative build tools for C or C++. The longer answer is that there are no declarative build tools because all the build tools aim to support all the insane build requirements of existing C or C++ projects. At that point embedding a turing complete scripting language actually makes for simpler build descriptions than some massive declarative system trying to handle all the corner cases. Of course, that raises the question: why don't any C or C++ build tools limit themselves to some sane subset of build requirements? That, I don't have a good answer for.
- mid-kid 2y ago
  In general this exists in order to detect features of the target compiler, libraries, platform and etc. A lot of languages can get away with making assumptions, due to either having only one implementation/compiler, supporting very few platforms/architectures or being otherwise insensitive to the environment.
juxtapose 2y ago
I think I'm for Turing-completeness. Let me try to give my reasons... 1. No, using Turing-complete scripts does not prevent information extraction and meaningful automation. You can ask the program to dump useful information, e.g. targets, compiler flags, etc. That's what rizsotto/Bear does for Makefile. CMAKE_EXPORT_COMPILE_COMMANDS is another example. 2. I don't really think you can do anything further with declarative build languages, unless it is a really limited one like JSON or XML. Meson (a relatively advanced one in the space) advocates for non-Turing-completeness, but you still cannot, for example, modify meson build files reliably using an external tool other than a text editor. 3. Complex build configuration usually requires non-trivial computation and/or dynamic dependency graph building. Turing-completeness gives you a possibility and you don't need to wait for build tool upgrades. Comparing Meson to CMake, I find the niceties of Meson are usually not inherently non-TC. That is, you can theoretically reimplement a nicer CMake with all the niceties of Meson, while still being TC.
JonChesterfield 2y ago
Makefiles are mostly declarative and very definitely turing complete when you want that. That's a good compromise, simple stuff is simple and complex stuff is possible. All a rigidly non-turin-complete build tool means is the day will come where you have to throw it away and rewrite everything in a more powerful language, probably at the last minute and with a bunch of fires taking light around you.

GrantMoyer 2y ago

In my experience the short answer is that there are no declarative build tools for C or C++. The longer answer is that there are no declarative build tools because all the build tools aim to support all the insane build requirements of existing C or C++ projects. At that point embedding a turing complete scripting language actually makes for simpler build descriptions than some massive declarative system trying to handle all the corner cases. Of course, that raises the question: why don't any C or C++ build tools limit themselves to some sane subset of build requirements? That, I don't have a good answer for.

mid-kid 2y ago
In general this exists in order to detect features of the target compiler, libraries, platform and etc. A lot of languages can get away with making assumptions, due to either having only one implementation/compiler, supporting very few platforms/architectures or being otherwise insensitive to the environment.

juxtapose 2y ago

I think I'm for Turing-completeness. Let me try to give my reasons... 1. No, using Turing-complete scripts does not prevent information extraction and meaningful automation. You can ask the program to dump useful information, e.g. targets, compiler flags, etc. That's what rizsotto/Bear does for Makefile. CMAKE_EXPORT_COMPILE_COMMANDS is another example. 2. I don't really think you can do anything further with declarative build languages, unless it is a really limited one like JSON or XML. Meson (a relatively advanced one in the space) advocates for non-Turing-completeness, but you still cannot, for example, modify meson build files reliably using an external tool other than a text editor. 3. Complex build configuration usually requires non-trivial computation and/or dynamic dependency graph building. Turing-completeness gives you a possibility and you don't need to wait for build tool upgrades. Comparing Meson to CMake, I find the niceties of Meson are usually not inherently non-TC. That is, you can theoretically reimplement a nicer CMake with all the niceties of Meson, while still being TC.

JonChesterfield 2y ago

Makefiles are mostly declarative and very definitely turing complete when you want that. That's a good compromise, simple stuff is simple and complex stuff is possible. All a rigidly non-turin-complete build tool means is the day will come where you have to throw it away and rewrite everything in a more powerful language, probably at the last minute and with a bunch of fires taking light around you.