Map size_t to usize by default and check compatibility [Rebased] #2278
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emilio
approved these changes
Sep 24, 2022
| layout.align == ctx.target_pointer_size(), | ||
| "Target platform requires --no-size_t-is-usize" | ||
| ); | ||
| } |
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Can we add the relevant values to the assertion error? Something like:
"Target platform requires --no-size_t-is-usize. {} size ({}) or align ({}) doesn't match target pointer size ({})", spelling, layout.size, layout.align, ctx.target_pointer_size()`
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@pvdrz you should have the ability to merge this when ready, lmk if that doesn't work for some reason. Please squash the rustfmt commit? |
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@emilio I'll do the change you asked and squash everything then. |
…ng#1901, rust-lang#1903) This addresses the underlying issue identified in rust-lang#1671, that size_t (integer that can hold any object size) isn't guaranteed to match usize, which is defined more like uintptr_t (integer that can hold any pointer). However, on almost all platforms, this is true, and in fact Rust already uses usize extensively in contexts where size_t would be more appropriate, such as slice indexing. So, it's better for ergonomics when interfacing with C code to map the C size_t type to usize. (See also discussion in rust-lang/rust#65473 about how usize really should be defined as size_t, not uintptr_t.) The previous fix for rust-lang#1671 removed the special case for size_t and defaulted to binding it as a normal typedef. This change effectively reverts that and goes back to mapping size_t to usize (and ssize_t to isize), but also ensures that if size_t is emitted, the typedef'd type of size_t in fact is compatible with usize (defined by checking that the size and alignment match the target pointer width). For (hypothetical) platforms where this is not true, or for compatibility with the default behavior of bindgen between 0.53 and this commit, onwards, you can disable this mapping with --no-size_t-is-usize.
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dspicher
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Nov 30, 2022
`size_t` has been aligned with `usize` [1], rendering the cast unnecessary. [1] rust-lang/rust-bindgen#2278
Aeradriel
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May 26, 2023
`size_t` has been aligned with `usize` [1], rendering the cast unnecessary. [1] rust-lang/rust-bindgen#2278
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Rebased version of #2062