Make broken MIR a proper lint. #119260

cjgillot · 2023-12-23T17:41:50Z

This allows to use expect(rustc::broken_mir) when we actually expect it to fire.

cc @tmiasko

@matthiaskrgr this should address #119077 (comment)

rustbot · 2023-12-23T17:41:57Z

r? @TaKO8Ki

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rustbot · 2023-12-23T17:41:59Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

compiler-errors · 2023-12-26T20:15:13Z

compiler/rustc_lint_defs/src/builtin.rs

+    /// The `broken_mir` statically detects undefined behaviour in the MIR optimization pipeline.
+    /// This is an internal lint, and not intended to be used directly.
+    pub rustc::BROKEN_MIR,
+    Deny,


Forbid maybe?

One use case is to use expect. And you cannot expect a forbidden lint.

tmiasko · 2023-12-27T20:26:53Z

compiler/rustc_lint_defs/src/builtin.rs

+crate::declare_tool_lint! {
+    /// The `broken_mir` statically detects undefined behaviour in the MIR optimization pipeline.
+    /// This is an internal lint, and not intended to be used directly.
+    pub rustc::BROKEN_MIR,
+    Deny,
+    "broken MIR",
+    report_in_external_macro: true
+}


Bike-shedding: The term broken MIR is already used when validation fails. It also overstates the severity of what is being reported. Maybe unusual MIR?

I do believe broken is the right term here

In what sense is this MIR broken?

The motivation behind moving those checks out of validator was the fact that there is nothing inherently wrong about violating them. Those reports should NOT be treated as bugs. It doesn't even mean that the user provided program has an undefined behaviour, since we don't know whether those instructions are ever executed.

bors · 2023-12-30T12:37:43Z

☔ The latest upstream changes (presumably #119377) made this pull request unmergeable. Please resolve the merge conflicts.

bors · 2024-01-05T19:28:16Z

☔ The latest upstream changes (presumably #119621) made this pull request unmergeable. Please resolve the merge conflicts.

compiler-errors · 2024-02-05T21:30:19Z

@rustbot author

Dylan-DPC · 2024-08-02T11:42:14Z

@cjgillot any updates on this? thanks

rust-log-analyzer · 2024-08-03T16:38:56Z

The job x86_64-gnu-llvm-17 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

------
 > importing cache manifest from ghcr.io/rust-lang/rust-ci-cache:3aacb9c90579defe09351ac5e8ee504359f8054da6326ff19038f1b7c90e3cb2aafe33685c6d9b76ee8d2ccbd187ca80c46ab5380485abdd8c0ce7d69cd8d8fd:
------
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-17]
---
sccache: Starting the server...
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-17', '--enable-llvm-link-shared', '--set', 'rust.thin-lto-import-instr-limit=10', '--set', 'change-id=99999999', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--enable-new-symbol-mangling']
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-17/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.thin-lto-import-instr-limit := 10
configure: change-id            := 99999999
---
##[group]Testing stage2 compiletest suite=crashes mode=crashes (x86_64-unknown-linux-gnu)

running 216 tests
........................................................................................  88/216
..........................2024-08-03T16:38:43.393835Z ERROR compiletest::runtest: fatal error, panic: "crashtest no longer crashes/triggers ICE, horray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge."
[crashes] tests/crashes/123810.rs ... F
............................................................. 176/216
........................................


failures:

---- [crashes] tests/crashes/123810.rs stdout ----

error: crashtest no longer crashes/triggers ICE, horray! Please give it a meaningful name, add a doc-comment to the start of the test explaining why it exists and move it to tests/ui or wherever you see fit. Adding 'Fixes #<issueNr>' to your PR description ensures that the corresponding ticket is auto-closed upon merge.
thread '[crashes] tests/crashes/123810.rs' panicked at src/tools/compiletest/src/runtest.rs:368:18:
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:

bors · 2024-08-19T10:03:55Z

☔ The latest upstream changes (presumably #129261) made this pull request unmergeable. Please resolve the merge conflicts.

JohnCSimon · 2025-02-05T21:44:12Z

@cjgillot

ping from triage - can you post your status on this PR? There hasn't been an update in a few months, and there are build and merge conflicts. Thanks!

FYI: when a PR is ready for review, send a message containing
@rustbot ready to switch to S-waiting-on-review so the PR is in the reviewer's backlog.

rustbot assigned TaKO8Ki Dec 23, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Dec 23, 2023

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compiler-errors reviewed Dec 26, 2023

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tmiasko reviewed Dec 27, 2023

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cjgillot force-pushed the mir-lint branch 2 times, most recently from 1176c87 to 0cbefd5 Compare January 1, 2024 02:43

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Feb 5, 2024

cjgillot added 3 commits August 3, 2024 16:04

Make broken MIR a proper lint.

1c121fb

Bless ui test.

f310e6c

Register lint with internal lints.

3f93be6

cjgillot force-pushed the mir-lint branch from 0cbefd5 to 3f93be6 Compare August 3, 2024 16:13

alex-semenyuk added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Oct 23, 2024

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Make broken MIR a proper lint. #119260

Make broken MIR a proper lint. #119260

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Make broken MIR a proper lint. #119260

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Make broken MIR a proper lint. #119260

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