BLD: default to C17 rather than C99 #20515
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Okay, nothing is ever a one line diff it seems .... the Windows failure is real (only with numpy 1.23.5): |
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So f2py C17 support in numpy seems to need some work/testing, it seems |
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I tested combinations of
numpy 1.26.x was the first minor version to be built with I have not yet checked if we can work around the problem somehow. |
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The root cause is a bug in older versions of |
This update should be a safe bump, because C17 is a pure maintenance update of C11 with no new features; and C11 is mostly a maintenance/bugfix update of C99 with a few new features. Our [toolchain roadmap](http://scipy.github.io/devdocs/dev/toolchain.html#c-compilers), which was updated just days ago, says that we can use C17 given our minimum compiler versions. I also note that in numpy#25072, the numpy default was updated from C99 to C11 and that went fine (the one change needed was a Cython bug fix, which went into Cython 3.0.6 - and our minimum version is currently 3.0.8). Finally, another motivation to do this now is that under the `--disable-gil` build of CPython 3.13, Cython currently generates code that uses `static_assert`, which is a C11 feature. Hence our current default of `-std=c99` doesn't build with that nogil build.
…build] Due to numpy#24761, which we hit when building against numpy versions <1.26.1
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Okay, this is all happy now. |
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Over in scikit-learn, we hit an issue building under pyiodide after moving to C17: scikit-learn/scikit-learn#29013. From what I can tell, scipy currently doesn't build under pyodide (#15290) due to missing fortran support, so scipy doesn't have a similar issue. However, if pyodide doesn't grow C17 support before that happens, then scipy specifying C17 in Just a heads' up! |
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Thanks for the heads up. Looking at getting that fixed in Meson (pyodide/pyodide#4762).
SciPy does build in Pyodide in-tree, it's at 1.12.0 right now with an update to 1.13.0 in progress. C17 support will become needed for 1.14.0 - we should have this fix included in a new Meson release by then. |
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Fix in progress: mesonbuild/meson#13221 |
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Hello, I was building Scipy in debug mode and got an error related with this thread. The full log tells this: Do you have any idea of how could I solve this? Edit: I tried changing the meson.build file, asking for |
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I'm not sure if Downgrading to |
This update should be a safe bump, because C17 is a pure maintenance update of C11 with no new features; and C11 is mostly a maintenance/bugfix update of C99 with a few new features. Our toolchain roadmap, which was updated just days ago, says that we can use C17 given our minimum compiler versions.
I also note that in numpy#25072, the numpy default was updated from C99 to C11 and that went fine (the one change needed was a Cython bug fix, which went into Cython 3.0.6 - and our minimum version is currently 3.0.8).
Finally, another motivation to do this now is that under the
--disable-gilbuild of CPython 3.13, Cython currently generates code that usesstatic_assert, which is a C11 feature. Hence our current default of-std=c99doesn't build with that nogil build. (hat tip to @ngoldbaum for pointing out this problem). EDIT: PEP 7 is also relevant here, since it specifies what C standard version is used by CPython (see https://peps.python.org/pep-0007/#c-dialect). To be safe, be should be using >= the version used by CPython.For a description of changes in C17, see https://gustedt.wordpress.com/2018/04/17/c17/.
Note: opening as draft until I've checked the CI logs for (the absence of) new warnings.