explain the MIR const vs TY const situation #1793
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RalfJung
commented
Sep 16, 2023
src/mir/index.md
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| @@ -255,7 +255,66 @@ but [you can read about those below](#promoted)). | |||
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| ## Representing constants | |||
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| *to be written* | |||
| When code has reached the MIR stage, constants can generally come in two forms: *MIR constants* ([`mir::Constant`]) and *type system constants* ([`ty::Const`]). | |||
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@oli-obk this makes me wonder if we should rename mir::Constant to mir::Const to match ty::Const...
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yea 😆 I wanted this forever, but never did it
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I can make a PR, but let's land rust-lang/rust#115865 first or this will be a hell of a conflict.^^
RalfJung
commented
Sep 16, 2023
| `"string literals"` and `b"byte string literals"`) has an optimized variant that | ||
| avoids the full overhead of the in-memory representation. | ||
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| ### ValTrees |
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This is arguably a bit misplaced in the MIR section, but I didn't find a "type system" section. previously it was in the const-eval section and that seems worse.
oli-obk
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Sep 16, 2023
matthiaskrgr
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Sep 26, 2023
Update books ## rust-embedded/book 1 commits in 99ad2847b865e96d8ae7b333d3ee96963557e621..eac173690b8cc99094e1d88bd49dd61127fbd285 2023-09-12 07:34:44 UTC to 2023-09-12 07:34:44 UTC - USB connector-type correction (rust-embedded/book#360) ## rust-lang/nomicon 1 commits in e3f3af69dce71cd37a785bccb7e58449197d940c..ddfa4214487686e91b21aa29afb972c08a8f0d5b 2023-09-22 17:04:10 UTC to 2023-09-22 17:04:10 UTC - Fill "Beneath `std`" (rust-lang/nomicon#413) ## rust-lang/reference 1 commits in ee7c676fd6e287459cb407337652412c990686c0..5262e1c3b43a2c489df8f6717683a44c7a2260fd 2023-09-18 18:28:31 UTC to 2023-09-18 18:28:31 UTC - we reserve the right to reduce our amount of UB (rust-lang/reference#1397) ## rust-lang/rustc-dev-guide 8 commits in 08bb147..a13b7c2 2023-09-25 05:14:41 UTC to 2023-09-11 21:29:18 UTC - Clarify all the `{AP,RP}IT{,IT}` impl trait types (rust-lang/rustc-dev-guide#1798) - Modify build instructions for optimized build (rust-lang/rustc-dev-guide#1795) - Remove outdated references to coverage debug code (rust-lang/rustc-dev-guide#1797) - Add deep dive document about early/late bound parameters interacting with turbofish (rust-lang/rustc-dev-guide#1794) - explain the MIR const vs TY const situation (rust-lang/rustc-dev-guide#1793) - fix type name (rust-lang/rustc-dev-guide#1792) - Clarify that `run-coverage` only runs in some of the CI jobs (rust-lang/rustc-dev-guide#1791) - Document the `coverage-map` and `run-coverage` test suites (rust-lang/rustc-dev-guide#1790)
matthiaskrgr
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Update books ## rust-embedded/book 1 commits in 99ad2847b865e96d8ae7b333d3ee96963557e621..eac173690b8cc99094e1d88bd49dd61127fbd285 2023-09-12 07:34:44 UTC to 2023-09-12 07:34:44 UTC - USB connector-type correction (rust-embedded/book#360) ## rust-lang/nomicon 1 commits in e3f3af69dce71cd37a785bccb7e58449197d940c..ddfa4214487686e91b21aa29afb972c08a8f0d5b 2023-09-22 17:04:10 UTC to 2023-09-22 17:04:10 UTC - Fill "Beneath `std`" (rust-lang/nomicon#413) ## rust-lang/reference 1 commits in ee7c676fd6e287459cb407337652412c990686c0..5262e1c3b43a2c489df8f6717683a44c7a2260fd 2023-09-18 18:28:31 UTC to 2023-09-18 18:28:31 UTC - we reserve the right to reduce our amount of UB (rust-lang/reference#1397) ## rust-lang/rustc-dev-guide 8 commits in 08bb147..a13b7c2 2023-09-25 05:14:41 UTC to 2023-09-11 21:29:18 UTC - Clarify all the `{AP,RP}IT{,IT}` impl trait types (rust-lang/rustc-dev-guide#1798) - Modify build instructions for optimized build (rust-lang/rustc-dev-guide#1795) - Remove outdated references to coverage debug code (rust-lang/rustc-dev-guide#1797) - Add deep dive document about early/late bound parameters interacting with turbofish (rust-lang/rustc-dev-guide#1794) - explain the MIR const vs TY const situation (rust-lang/rustc-dev-guide#1793) - fix type name (rust-lang/rustc-dev-guide#1792) - Clarify that `run-coverage` only runs in some of the CI jobs (rust-lang/rustc-dev-guide#1791) - Document the `coverage-map` and `run-coverage` test suites (rust-lang/rustc-dev-guide#1790)
rust-timer
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Sep 26, 2023
Rollup merge of rust-lang#116153 - rustbot:docs-update, r=ehuss Update books ## rust-embedded/book 1 commits in 99ad2847b865e96d8ae7b333d3ee96963557e621..eac173690b8cc99094e1d88bd49dd61127fbd285 2023-09-12 07:34:44 UTC to 2023-09-12 07:34:44 UTC - USB connector-type correction (rust-embedded/book#360) ## rust-lang/nomicon 1 commits in e3f3af69dce71cd37a785bccb7e58449197d940c..ddfa4214487686e91b21aa29afb972c08a8f0d5b 2023-09-22 17:04:10 UTC to 2023-09-22 17:04:10 UTC - Fill "Beneath `std`" (rust-lang/nomicon#413) ## rust-lang/reference 1 commits in ee7c676fd6e287459cb407337652412c990686c0..5262e1c3b43a2c489df8f6717683a44c7a2260fd 2023-09-18 18:28:31 UTC to 2023-09-18 18:28:31 UTC - we reserve the right to reduce our amount of UB (rust-lang/reference#1397) ## rust-lang/rustc-dev-guide 8 commits in 08bb147..a13b7c2 2023-09-25 05:14:41 UTC to 2023-09-11 21:29:18 UTC - Clarify all the `{AP,RP}IT{,IT}` impl trait types (rust-lang/rustc-dev-guide#1798) - Modify build instructions for optimized build (rust-lang/rustc-dev-guide#1795) - Remove outdated references to coverage debug code (rust-lang/rustc-dev-guide#1797) - Add deep dive document about early/late bound parameters interacting with turbofish (rust-lang/rustc-dev-guide#1794) - explain the MIR const vs TY const situation (rust-lang/rustc-dev-guide#1793) - fix type name (rust-lang/rustc-dev-guide#1792) - Clarify that `run-coverage` only runs in some of the CI jobs (rust-lang/rustc-dev-guide#1791) - Document the `coverage-map` and `run-coverage` test suites (rust-lang/rustc-dev-guide#1790)
marxin
reviewed
Jul 24, 2024
| @@ -283,3 +351,5 @@ See the const-eval WG's [docs on promotion](https://github.com/rust-lang/const-e | |||
| [`ProjectionElem::Deref`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/enum.ProjectionElem.html#variant.Deref | |||
| [`Rvalue`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/enum.Rvalue.html | |||
| [`Operand`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/enum.Operand.html | |||
| [`mir::Constant`]: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_middle/mir/struct.Constant.html | |||
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It seems the link is invalid right now and I can't easily find the corresponding struct type the link should point to.
@RalfJung: Can you please address it?
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mir::Constant has been renamed to this.
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Great! I'm going to include it in #2024.
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