Allow transmute casts in pre-runtime-MIR #142124
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Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt This PR changes MIR |
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I think That said, I could have sworn there was more that would have been needed here. If this is in |
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Transmute is a boundary for type and lifetime information. Even dropck is basically treating it as an opaque function that consumes its argument and produces a new value of the return type. Move checking handles it correctly as it does process the input operand together with all casts. The only interesting tidbit is probably that borrowck will ICE if you use any type other than a pattern type. |
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Allow transmute casts in pre-runtime-MIR r? `@scottmcm` cc `@BoxyUwU` turns out in rust-lang#138393 I erroneously used transmute casts in https://github.com/rust-lang/rust/blob/fd3da4bebdff63b7529483ff7025986ef16bf463/compiler/rustc_mir_build/src/builder/matches/test.rs#L209 I don't think they have any issues using them before runtime, we just checked for them because we didn't have code exercising those code paths
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Rollup of 14 pull requests Successful merges: - #134442 (Specify the behavior of `file!`) - #134841 (Look at proc-macro attributes when encountering unknown attribute) - #140372 (Exhaustively handle parsed attributes in CheckAttr) - #140766 (Stabilize keylocker) - #141642 (Note the version and PR of removed features when using it) - #141909 (Add central execution context to bootstrap) - #141992 (use `#[naked]` for `__rust_probestack`) - #142102 (docs: Small clarification on the usage of read_to_string and read_to_end trait methods) - #142124 (Allow transmute casts in pre-runtime-MIR) - #142240 (deduplicate the rest of AST walker functions) - #142258 (platform-support.md: Mention specific Linux kernel version or later) - #142262 (Mark `core::slice::memchr` as `#[doc(hidden)]`) - #142271 (compiler: fn ptrs should hit different lints based on ABI) - #142288 (const_eval: fix some outdated comments) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup of 16 pull requests Successful merges: - #134442 (Specify the behavior of `file!`) - #140372 (Exhaustively handle parsed attributes in CheckAttr) - #140766 (Stabilize keylocker) - #141642 (Note the version and PR of removed features when using it) - #141818 (Don't create .msi installer for gnullvm hosts) - #141909 (Add central execution context to bootstrap) - #141992 (use `#[naked]` for `__rust_probestack`) - #142101 (core::ptr: deduplicate more method docs) - #142102 (docs: Small clarification on the usage of read_to_string and read_to_end trait methods) - #142124 (Allow transmute casts in pre-runtime-MIR) - #142240 (deduplicate the rest of AST walker functions) - #142258 (platform-support.md: Mention specific Linux kernel version or later) - #142262 (Mark `core::slice::memchr` as `#[doc(hidden)]`) - #142271 (compiler: fn ptrs should hit different lints based on ABI) - #142275 (rustdoc: Refractor `clean_ty_generics`) - #142288 (const_eval: fix some outdated comments) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of #142124 - oli-obk:transmute-cast, r=scottmcm Allow transmute casts in pre-runtime-MIR r? ``@scottmcm`` cc ``@BoxyUwU`` turns out in #138393 I erroneously used transmute casts in https://github.com/rust-lang/rust/blob/fd3da4bebdff63b7529483ff7025986ef16bf463/compiler/rustc_mir_build/src/builder/matches/test.rs#L209 I don't think they have any issues using them before runtime, we just checked for them because we didn't have code exercising those code paths
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r? @scottmcm
cc @BoxyUwU
turns out in #138393 I erroneously used transmute casts in
rust/compiler/rustc_mir_build/src/builder/matches/test.rs
Line 209 in fd3da4b
I don't think they have any issues using them before runtime, we just checked for them because we didn't have code exercising those code paths