unstably allow constants to refer to statics and read from immutable statics #119614
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
rustbot
added
S-waiting-on-review
|
The Miri subtree was changed cc @rust-lang/miri Some changes occurred to the CTFE / Miri engine cc @rust-lang/miri Some changes occurred to the CTFE / Miri engine cc @rust-lang/miri |
oli-obk
approved these changes
Jan 5, 2024
fmease
reviewed
Jan 5, 2024
tests/ui/feature-gates/feature-gate-const-refs-to-static.stderr
Outdated
Show resolved
Hide resolved
6 tasks
RalfJung
force-pushed
the
const-refs-to-static
branch
2 times, most recently
from
768c020 to
7f21ace
Compare
fmease
reviewed
Jan 5, 2024
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
2 times, most recently
from
6a0f1bc to
1ad4b85
Compare
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
from
1ad4b85 to
8db79e5
Compare
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
from
8db79e5 to
8344f1b
Compare
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
from
8344f1b to
60b12fd
Compare
|
Some changes occurred to MIR optimizations cc @rust-lang/wg-mir-opt |
|
I realized I have to make validation descend into statics, or else valtree construction can encounter unvalidated data. This also makes the feature more conservative: consts that refer to mutable memory behind a shared reference are immediately rejected, not just when they are used as a pattern. |
RalfJung
force-pushed
the
const-refs-to-static
branch
from
d9943e9 to
0eb6726
Compare
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
from
0eb6726 to
aee26a8
Compare
This comment has been minimized.
This comment has been minimized.
This comment has been minimized.
This comment has been minimized.
RalfJung
force-pushed
the
const-refs-to-static
branch
from
aea0509 to
c7cca7c
Compare
|
seems fishy to allow valtrees to read from immutable statics. That means we meaningfully lose the static's identity during rountdrip. |
|
Valtrees are about the value. How would the static's identity matter? |
|
@bors r- conflicts |
bors
added
S-waiting-on-author
RalfJung
force-pushed
the
const-refs-to-static
branch
from
ea7654f to
4def373
Compare
|
@bors r=oli-obk |
bors
added
S-waiting-on-bors
|
☀️ Test successful - checks-actions |
|
Finished benchmarking commit (6cc4843): comparison URL. Overall result: ❌ regressions - no action needed@rustbot label: -perf-regression Instruction countThis is a highly reliable metric that was used to determine the overall result at the top of this comment.
Max RSS (memory usage)ResultsThis is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
CyclesThis benchmark run did not return any relevant results for this metric. Binary sizeResultsThis is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.
Bootstrap: 666.587s -> 667.259s (0.10%) |
matthiaskrgr
added a commit
to matthiaskrgr/rust
that referenced
this pull request
Feb 12, 2024
…li-obk add another test for promoteds-in-static rust-lang#119614 led to validation of promoteds recursing into statics. These statics can point to `static mut` and interior mutable `static` and do other things we don't allow in `const`, but promoteds are validated as `const`, so we get strange errors (saying "in `const`" when there is no const) and surprising validation failures. rust-lang#120960 fixes that; this here adds another test. r? `@oli-obk` Fixes rust-lang#120968
matthiaskrgr
added a commit
to matthiaskrgr/rust
that referenced
this pull request
Feb 12, 2024
…li-obk add another test for promoteds-in-static rust-lang#119614 led to validation of promoteds recursing into statics. These statics can point to `static mut` and interior mutable `static` and do other things we don't allow in `const`, but promoteds are validated as `const`, so we get strange errors (saying "in `const`" when there is no const) and surprising validation failures. rust-lang#120960 fixes that; this here adds another test. r? ``@oli-obk`` Fixes rust-lang#120968
rust-timer
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Feb 13, 2024
Rollup merge of rust-lang#120970 - RalfJung:static-promoted-test, r=oli-obk add another test for promoteds-in-static rust-lang#119614 led to validation of promoteds recursing into statics. These statics can point to `static mut` and interior mutable `static` and do other things we don't allow in `const`, but promoteds are validated as `const`, so we get strange errors (saying "in `const`" when there is no const) and surprising validation failures. rust-lang#120960 fixes that; this here adds another test. r? ``@oli-obk`` Fixes rust-lang#120968
github-actions bot
pushed a commit
to rust-lang/miri
that referenced
this pull request
Feb 13, 2024
add another test for promoteds-in-static rust-lang/rust#119614 led to validation of promoteds recursing into statics. These statics can point to `static mut` and interior mutable `static` and do other things we don't allow in `const`, but promoteds are validated as `const`, so we get strange errors (saying "in `const`" when there is no const) and surprising validation failures. rust-lang/rust#120960 fixes that; this here adds another test. r? ``@oli-obk`` Fixes rust-lang/rust#120968
90 tasks
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
I am not aware of any fundamental reason why we cannot allow constants to mention statics. What we really need is that constants do not read from statics that can change their value:
r? @oli-obk -- if you are okay with experimenting with this feature, I will create a tracking issue.
Based on and blocked on #119044; only the last commit is new.