Add simpler entry points to const eval for common usages. #66877

BenLewis-Seequent · 2019-11-29T20:15:26Z

I found the tcx.const_eval API to be complex/awkward to work with, because of the inherent complexity from all of the different situations it is called from. Though it mainly used in one of the following ways:

Evaluates the value of a constant without any substitutions, e.g. evaluating a static, discriminant, etc.
Evaluates the value of a resolved instance of a constant. this happens when evaluating unevaluated constants or normalising trait constants.
Evaluates a promoted constant.

This PR adds three new functions const_eval_mono, const_eval_resolve, and const_eval_promoted to TyCtxt, which each cater to one of the three ways tcx.const_eval
is normally used.

matthewjasper · 2019-11-29T20:17:48Z

r? @oli-obk
cc @eddyb

src/librustc/mir/interpret/mod.rs

rust-highfive · 2019-11-29T20:33:34Z

The job x86_64-gnu-llvm-6.0 of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

2019-11-29T20:16:09.2724085Z ##[command]git remote add origin https://github.com/rust-lang/rust
2019-11-29T20:16:09.2887227Z ##[command]git config gc.auto 0
2019-11-29T20:16:09.2952066Z ##[command]git config --get-all http.https://github.com/rust-lang/rust.extraheader
2019-11-29T20:16:10.1083580Z ##[command]git config --get-all http.proxy
2019-11-29T20:16:10.1094395Z ##[command]git -c http.extraheader="AUTHORIZATION: basic ***" fetch --force --tags --prune --progress --no-recurse-submodules --depth=2 origin +refs/heads/*:refs/remotes/origin/* +refs/pull/66877/merge:refs/remotes/pull/66877/merge
---
2019-11-29T20:21:45.1084103Z    Compiling serde_json v1.0.40
2019-11-29T20:21:46.6978396Z    Compiling tidy v0.1.0 (/checkout/src/tools/tidy)
2019-11-29T20:21:56.9171684Z     Finished release [optimized] target(s) in 1m 21s
2019-11-29T20:21:56.9262880Z tidy check
2019-11-29T20:21:57.7391025Z tidy error: /checkout/src/librustc/mir/interpret/mod.rs:611: line longer than 100 chars
2019-11-29T20:21:57.7391459Z tidy error: /checkout/src/librustc/mir/interpret/mod.rs: missing trailing newline
2019-11-29T20:21:59.5172759Z some tidy checks failed
2019-11-29T20:21:59.5178863Z Found 486 error codes
2019-11-29T20:21:59.5178934Z Found 0 error codes with no tests
2019-11-29T20:21:59.5178981Z Done!
2019-11-29T20:21:59.5178981Z Done!
2019-11-29T20:21:59.5184647Z 
2019-11-29T20:21:59.5184980Z 
2019-11-29T20:21:59.5185828Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/tidy" "/checkout/src" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "--no-vendor"
2019-11-29T20:21:59.5186183Z 
2019-11-29T20:21:59.5186280Z 
2019-11-29T20:21:59.5186567Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/tools/tidy
2019-11-29T20:21:59.5186999Z Build completed unsuccessfully in 0:01:24
2019-11-29T20:21:59.5186999Z Build completed unsuccessfully in 0:01:24
2019-11-29T20:21:59.5242662Z == clock drift check ==
2019-11-29T20:21:59.5263961Z   local time: Fri Nov 29 20:21:59 UTC 2019
2019-11-29T20:21:59.8129915Z   network time: Fri, 29 Nov 2019 20:21:59 GMT
2019-11-29T20:21:59.8132404Z == end clock drift check ==
2019-11-29T20:22:01.1054298Z 
2019-11-29T20:22:01.1152256Z ##[error]Bash exited with code '1'.
2019-11-29T20:22:01.1178757Z ##[section]Starting: Checkout
2019-11-29T20:22:01.1180412Z ==============================================================================
2019-11-29T20:22:01.1180667Z Task         : Get sources
2019-11-29T20:22:01.1180723Z Description  : Get sources from a repository. Supports Git, TfsVC, and SVN repositories.

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @TimNN. (Feature Requests)

src/librustc/mir/interpret/mod.rs

RalfJung · 2019-11-29T22:07:59Z

src/librustc/mir/interpret/mod.rs

@@ -554,3 +556,70 @@ pub fn truncate(value: u128, size: Size) -> u128 {
    // Truncate (shift left to drop out leftover values, shift right to fill with zeroes).
    (value << shift) >> shift
 }
+
+
+impl<'tcx> TyCtxt<'tcx> {


Why are these added in this file, as opposed to next to const_eval or so?

Scrolling over this file, the only coherent description of it that I can come up with is "random stuff".^^

They need to be within librustc as they are used inside it. I'm not sure where the best place is.

maybe just put them into a submodule of this module. queries could work as a name.

oli-obk

Maybe rename the query to const_eval_global_id (or if it is unused except forin the three wrappers, name it const_eval_internal and leave a comment on it suggesting the use of the wrappers).

I worry that otherwise we'll just reintroduce calls to it that manually do all the boilerplate

src/librustc/mir/interpret/mod.rs

BenLewis-Seequent · 2019-11-30T21:49:59Z

I introduced another wrapper const_eval_instance so I could rename the query to const_eval_internal, which is only used by these wrappers and also inside const_eval_internal itself. Although I'm not sure that const_eval_instance is even needed as the only uses of it is for the type_name intrinsic, which could use const_eval_resolve, but we already have the instance.

RalfJung · 2019-12-01T21:31:38Z

So we have const_eval_raw and const_eval_internal? That seems potentially confusing. Please make sure that at least both some with extensive doc comments explaining their difference.

joelpalmer · 2019-12-09T13:27:10Z

Ping from Triage: Hi @Skinny121 - any updates?

BenLewis-Seequent · 2019-12-11T07:40:44Z

@RalfJung I have added to the doc comments explaining the difference between both of these queries.

bors · 2019-12-11T08:41:47Z

☔ The latest upstream changes (presumably #67202) made this pull request unmergeable. Please resolve the merge conflicts.

src/librustc/query/mod.rs

BenLewis-Seequent · 2019-12-20T07:40:52Z

@RalfJung @oli-obk Is there anything more I need to change?

src/librustc_mir/hair/cx/expr.rs

oli-obk · 2019-12-22T12:32:25Z

@bors r+

bors · 2019-12-22T12:32:26Z

📌 Commit c010d84 has been approved by oli-obk

bors · 2019-12-22T12:32:27Z

🌲 The tree is currently closed for pull requests below priority 100, this pull request will be tested once the tree is reopened

…r=oli-obk Add simpler entry points to const eval for common usages. I found the `tcx.const_eval` API to be complex/awkward to work with, because of the inherent complexity from all of the different situations it is called from. Though it mainly used in one of the following ways: - Evaluates the value of a constant without any substitutions, e.g. evaluating a static, discriminant, etc. - Evaluates the value of a resolved instance of a constant. this happens when evaluating unevaluated constants or normalising trait constants. - Evaluates a promoted constant. This PR adds three new functions `const_eval_mono`, `const_eval_resolve`, and `const_eval_promoted` to `TyCtxt`, which each cater to one of the three ways `tcx.const_eval` is normally used.

@ghost

Rollup of 8 pull requests Successful merges: - #66877 (Add simpler entry points to const eval for common usages.) - #67299 (Add `ImmTy::try_from_(u)int` methods) - #67487 (Rustdoc mutability removal) - #67499 (Misc MIR building cleanups) - #67506 (Remove iter_private.rs) - #67508 (Fix typo in path parser name) - #67519 (Document why Any is not an unsafe trait) - #67525 (Utilize rust-lang/rust commit hashes in toolstate) Failed merges: r? @ghost

Rustup to rust-lang/rust#66877 changelog: none

rust-highfive assigned matthewjasper Nov 29, 2019

rust-highfive assigned oli-obk and unassigned matthewjasper Nov 29, 2019

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rustc_typeck: gate AnonConst's generics on feature(const_generics). #66883

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varkor added A-const-generics Area: const generics (parameters and arguments) F-const_generics `#![feature(const_generics)]` and removed A-const-generics Area: const generics (parameters and arguments) labels Dec 14, 2019

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Add simpler entry points to const eval for common usages.

c010d84

BenLewis-Seequent force-pushed the const-eval-entry-points branch from 8707e98 to c010d84 Compare December 21, 2019 22:16

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Dec 22, 2019

oli-obk mentioned this pull request Dec 22, 2019

Various const eval and pattern matching ICE fixes #67192

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Centril mentioned this pull request Dec 22, 2019

Rollup of 6 pull requests #67522

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Rollup of 7 pull requests #67526

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Rollup of 8 pull requests #67532

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bors merged commit c010d84 into rust-lang:master Dec 22, 2019

matthiaskrgr added a commit to matthiaskrgr/rust-clippy that referenced this pull request Dec 22, 2019

rustup rust-lang/rust#66877

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JohnTitor added a commit to JohnTitor/rust-clippy that referenced this pull request Dec 23, 2019

Rustup to rust-lang/rust#66877

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bors added a commit to rust-lang/rust-clippy that referenced this pull request Dec 23, 2019

Auto merge of #4944 - JohnTitor:rustup, r=oli-obk

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Rustup to rust-lang/rust#66877 changelog: none

varkor mentioned this pull request Jan 2, 2020

Tracking issue for const generics (RFC 2000) #44580

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Add simpler entry points to const eval for common usages. #66877

Add simpler entry points to const eval for common usages. #66877

BenLewis-Seequent commented Nov 29, 2019

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Add simpler entry points to const eval for common usages. #66877

Add simpler entry points to const eval for common usages. #66877

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