const_prop_lint: Consider array length constant even if array is not #100160

TheWastl · 2022-08-05T04:21:07Z

Fixes #98444.

rust-highfive · 2022-08-05T04:21:10Z

r? @compiler-errors

(rust-highfive has picked a reviewer for you, use r? to override)

rustbot · 2022-08-05T04:21:10Z

Some changes occurred to MIR optimizations

cc @rust-lang/wg-mir-opt

compiler-errors · 2022-08-05T04:51:02Z

r? oli-obk

cc @JakobDegen

RalfJung · 2022-08-05T14:17:02Z

r? @oli-obk

wesleywiser · 2022-08-05T14:33:20Z

compiler/rustc_mir_transform/src/const_prop_lint.rs

@@ -501,12 +501,23 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
                return None;
            }

+            Rvalue::Len(len_place) => {


I think we should make the same change in the const_prop pass as well:

rust/compiler/rustc_mir_transform/src/const_prop.rs

Line 624 in 9bbbf60

| Rvalue::Len(..)

but that doesn't have to be in this PR 🙂

afaicr this is not necessary, because there are optimizations taking care of this before const prop runs

oli-obk · 2022-08-25T10:15:04Z

@bors r+ rollup

bors · 2022-08-25T10:15:06Z

📌 Commit e4a4246 has been approved by oli-obk

It is now in the queue for this repository.

…nt, r=oli-obk const_prop_lint: Consider array length constant even if array is not Fixes rust-lang#98444.

JohnTitor · 2022-08-26T00:51:22Z

Failed in rollup: #101016 (comment)
@bors r-

rustbot · 2022-09-05T18:29:32Z

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

rust-log-analyzer · 2022-09-05T20:51:37Z

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

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

  IMAGE: x86_64-gnu-tools
##[endgroup]
From https://github.com/rust-lang/rust
 * branch              master     -> FETCH_HEAD
Searching for toolstate changes between 2dc703fd6e3aaaf343828cc7dd1aec192d24c628 and c83902e575b2da5c0ce00966b6215feadda35d4b
Clippy or rustfmt subtrees were updated
##[group]Run src/ci/scripts/verify-channel.sh
src/ci/scripts/verify-channel.sh
shell: /usr/bin/bash --noprofile --norc -e -o pipefail {0}
env:
---
diff of stderr:

-error: this operation will panic at runtime
-  --> $DIR/indexing_slicing_index.rs:23:5
-   |
-LL |     x[4]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays.
-   |     ^^^^ index out of bounds: the length is 4 but the index is 4
-   |
-   = note: `#[deny(unconditional_panic)]` on by default
-error: this operation will panic at runtime
-  --> $DIR/indexing_slicing_index.rs:24:5
-   |
-   |
-LL |     x[1 << 3]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays.
-   |     ^^^^^^^^^ index out of bounds: the length is 4 but the index is 8
-error: this operation will panic at runtime
-  --> $DIR/indexing_slicing_index.rs:29:5
-   |
-   |
-LL |     x[const { idx4() }]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays.
-   |     ^^^^^^^^^^^^^^^^^^^ index out of bounds: the length is 4 but the index is 4
-
 error[E0080]: evaluation of `main::{constant#3}` failed
    |
    |
 LL |     const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.
    |              ^^^^^^^^^^^ index out of bounds: the length is 2 but the index is 4
 error[E0080]: erroneous constant used
   --> $DIR/indexing_slicing_index.rs:31:5
    |
    |
 LL |     const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.
 
-error: this operation will panic at runtime
-  --> $DIR/indexing_slicing_index.rs:35:5
-   |
-   |
-LL |     y[4]; // Ok, rustc will handle references too.
-   |     ^^^^ index out of bounds: the length is 4 but the index is 4
-error: this operation will panic at runtime
-  --> $DIR/indexing_slicing_index.rs:44:5
-   |
-   |
-LL |     x[N]; // Ok, let rustc's `unconditional_panic` lint handle `usize` indexing on arrays.
-   |     ^^^^ index out of bounds: the length is 4 but the index is 15
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:22:5
    |
 LL |     x[index];
 LL |     x[index];
    |     ^^^^^^^^
    |
    = note: `-D clippy::indexing-slicing` implied by `-D warnings`
    = help: consider using `.get(n)` or `.get_mut(n)` instead
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:38:5
    |
 LL |     v[0];
 LL |     v[0];
    |     ^^^^
    |
    = help: consider using `.get(n)` or `.get_mut(n)` instead
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:39:5
    |
 LL |     v[10];
 LL |     v[10];
    |     ^^^^^
    |
    = help: consider using `.get(n)` or `.get_mut(n)` instead
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:40:5
    |
    |
 LL |     v[1 << 3];
    |
    |
    = help: consider using `.get(n)` or `.get_mut(n)` instead
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:46:5
    |
 LL |     v[N];
 LL |     v[N];
    |     ^^^^
    |
    = help: consider using `.get(n)` or `.get_mut(n)` instead
 error: indexing may panic
   --> $DIR/indexing_slicing_index.rs:47:5
    |
 LL |     v[M];
 LL |     v[M];
    |     ^^^^
    |
    = help: consider using `.get(n)` or `.get_mut(n)` instead
-error: aborting due to 13 previous errors
+error: aborting due to 8 previous errors
 
 For more information about this error, try `rustc --explain E0080`.
---

error: 1 errors occurred comparing output.
status: exit status: 1
error: test failed, to rerun pass '--test compile-test'
command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/clippy-driver" "tests/ui/indexing_slicing_index.rs" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/test/ui" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/test/ui/indexing_slicing_index.stage-id" "-A" "unused" "--emit=metadata" "-Dwarnings" "-Zui-testing" "-L" "dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps" "-L" "dependency=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/release/deps" "--extern" "tokio=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libtokio-e0524b7e2611e851.rlib" "--extern" "rustc_semver=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/librustc_semver-963bbd3f89834643.rlib" "--extern" "itertools=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libitertools-cdd893c121eb00e4.rlib" "--extern" "parking_lot=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libparking_lot-4554cde6a1339e03.rlib" "--extern" "serde=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libserde-4b46e2e2788394f2.rlib" "--extern" "clippy_lints=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libclippy_lints-a74d54f3750f2f75.rlib" "--extern" "serde_derive=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/release/deps/libserde_derive-eed8221ad604f845.so" "--extern" "clippy_utils=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libclippy_utils-47229815ed3188f9.rlib" "--extern" "if_chain=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libif_chain-03f75cdc6d4d3afc.rlib" "--extern" "quote=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libquote-021aec868151835c.rlib" "--extern" "futures=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libfutures-e92c80438a94fde5.rlib" "--extern" "derive_new=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/release/deps/libderive_new-14dbc812a1f5dba0.so" "--extern" "syn=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libsyn-c6aa3eacac0eeebb.rlib" "--extern" "regex=/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/deps/libregex-619ac20e364f2b2c.rlib" "--edition=2021" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-unknown-linux-gnu/release/test/ui/indexing_slicing_index.stage-id.aux"
------------------------------------------

------------------------------------------
stderr:
stderr:
------------------------------------------
{"message":"evaluation of `main::{constant#3}` failed","code":{"code":"E0080","explanation":"A constant value failed to get evaluated.\n\nErroneous code example:\n\n```compile_fail,E0080\nenum Enum {\n    X = (1 << 500),\n    Y = (1 / 0),\n}\n```\n\nThis error indicates that the compiler was unable to sensibly evaluate a\nconstant expression that had to be evaluated. Attempting to divide by 0\nor causing an integer overflow are two ways to induce this error.\n\nEnsure that the expressions given can be evaluated as the desired integer type.\n\nSee the [Custom Discriminants][custom-discriminants] section of the Reference\nfor more information about setting custom integer types on fieldless enums\nusing the [`repr` attribute][repr-attribute].\n\n[custom-discriminants]: https://doc.rust-lang.org/reference/items/enumerations.html#custom-discriminant-values-for-field-less-enumerations\n[repr-attribute]: https://doc.rust-lang.org/reference/type-layout.html#reprc-enums\n"},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1157,"byte_end":1168,"line_start":31,"line_end":31,"column_start":14,"column_end":25,"is_primary":true,"text":[{"text":"    const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.","highlight_start":14,"highlight_end":25}],"label":"index out of bounds: the length is 2 but the index is 4","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0080]: evaluation of `main::{constant#3}` failed\n  --> tests/ui/indexing_slicing_index.rs:31:14\n   |\nLL |     const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.\n   |              ^^^^^^^^^^^ index out of bounds: the length is 2 but the index is 4\n\n"}
{"message":"erroneous constant used","code":{"code":"E0080","explanation":"A constant value failed to get evaluated.\n\nErroneous code example:\n\n```compile_fail,E0080\nenum Enum {\n    X = (1 << 500),\n    Y = (1 / 0),\n}\n```\n\nThis error indicates that the compiler was unable to sensibly evaluate a\nconstant expression that had to be evaluated. Attempting to divide by 0\nor causing an integer overflow are two ways to induce this error.\n\nEnsure that the expressions given can be evaluated as the desired integer type.\n\nSee the [Custom Discriminants][custom-discriminants] section of the Reference\nfor more information about setting custom integer types on fieldless enums\nusing the [`repr` attribute][repr-attribute].\n\n[custom-discriminants]: https://doc.rust-lang.org/reference/items/enumerations.html#custom-discriminant-values-for-field-less-enumerations\n[repr-attribute]: https://doc.rust-lang.org/reference/type-layout.html#reprc-enums\n"},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1148,"byte_end":1170,"line_start":31,"line_end":31,"column_start":5,"column_end":27,"is_primary":true,"text":[{"text":"    const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.","highlight_start":5,"highlight_end":27}],"label":"referenced constant has errors","suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[],"rendered":"error[E0080]: erroneous constant used\n  --> tests/ui/indexing_slicing_index.rs:31:5\n   |\nLL |     const { &ARR[idx4()] }; // Ok, let rustc handle const contexts.\n   |     ^^^^^^^^^^^^^^^^^^^^^^ referenced constant has errors\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":633,"byte_end":641,"line_start":22,"line_end":22,"column_start":5,"column_end":13,"is_primary":true,"text":[{"text":"    x[index];","highlight_start":5,"highlight_end":13}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"`-D clippy::indexing-slicing` implied by `-D warnings`","code":null,"level":"note","spans":[],"children":[],"rendered":null},{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:22:5\n   |\nLL |     x[index];\n   |     ^^^^^^^^\n   |\n   = note: `-D clippy::indexing-slicing` implied by `-D warnings`\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1385,"byte_end":1389,"line_start":38,"line_end":38,"column_start":5,"column_end":9,"is_primary":true,"text":[{"text":"    v[0];","highlight_start":5,"highlight_end":9}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:38:5\n   |\nLL |     v[0];\n   |     ^^^^\n   |\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1395,"byte_end":1400,"line_start":39,"line_end":39,"column_start":5,"column_end":10,"is_primary":true,"text":[{"text":"    v[10];","highlight_start":5,"highlight_end":10}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:39:5\n   |\nLL |     v[10];\n   |     ^^^^^\n   |\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1406,"byte_end":1415,"line_start":40,"line_end":40,"column_start":5,"column_end":14,"is_primary":true,"text":[{"text":"    v[1 << 3];","highlight_start":5,"highlight_end":14}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:40:5\n   |\nLL |     v[1 << 3];\n   |     ^^^^^^^^^\n   |\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1636,"byte_end":1640,"line_start":46,"line_end":46,"column_start":5,"column_end":9,"is_primary":true,"text":[{"text":"    v[N];","highlight_start":5,"highlight_end":9}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:46:5\n   |\nLL |     v[N];\n   |     ^^^^\n   |\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"indexing may panic","code":{"code":"clippy::indexing_slicing","explanation":null},"level":"error","spans":[{"file_name":"tests/ui/indexing_slicing_index.rs","byte_start":1646,"byte_end":1650,"line_start":47,"line_end":47,"column_start":5,"column_end":9,"is_primary":true,"text":[{"text":"    v[M];","highlight_start":5,"highlight_end":9}],"label":null,"suggested_replacement":null,"suggestion_applicability":null,"expansion":null}],"children":[{"message":"consider using `.get(n)` or `.get_mut(n)` instead","code":null,"level":"help","spans":[],"children":[],"rendered":null}],"rendered":"error: indexing may panic\n  --> tests/ui/indexing_slicing_index.rs:47:5\n   |\nLL |     v[M];\n   |     ^^^^\n   |\n   = help: consider using `.get(n)` or `.get_mut(n)` instead\n\n"}
{"message":"For more information about this error, try `rustc --explain E0080`.","code":null,"level":"failure-note","spans":[],"children":[],"rendered":"For more information about this error, try `rustc --explain E0080`.\n"}

------------------------------------------

JohnCSimon · 2022-10-02T21:56:38Z

Ping from triage:
@TheWastl - can you post your status on this MR?

bors · 2022-10-08T00:23:31Z

☔ The latest upstream changes (presumably #102091) made this pull request unmergeable. Please resolve the merge conflicts.

JohnCSimon · 2022-11-27T04:32:15Z

@TheWastl
Ping from triage: I'm closing this due to inactivity, Please reopen when you are ready to continue with this.
Note: if you do please open the PR BEFORE you push to it, else you won't be able to reopen - this is a quirk of github.
Thanks for your contribution.

@rustbot label: +S-inactive

rust-highfive assigned compiler-errors Aug 5, 2022

rustbot added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Aug 5, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Aug 5, 2022

TheWastl mentioned this pull request Aug 5, 2022

const_eval: Consider array length constant even if array is not #99594

Closed

rust-highfive assigned oli-obk and unassigned compiler-errors Aug 5, 2022

wesleywiser reviewed Aug 5, 2022

View reviewed changes

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-review Status: Awaiting review from the assignee but also interested parties. labels Aug 25, 2022

JohnTitor added a commit to JohnTitor/rust that referenced this pull request Aug 25, 2022

Rollup merge of rust-lang#100160 - TheWastl:issue-98444-const_prop_li…

911878e

…nt, r=oli-obk const_prop_lint: Consider array length constant even if array is not Fixes rust-lang#98444.

JohnTitor mentioned this pull request Aug 25, 2022

Rollup of 9 pull requests #101016

Closed

bors 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-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Aug 26, 2022

const_prop_lint: Consider array length constant even if array is not

d5c9e76

TheWastl force-pushed the issue-98444-const_prop_lint branch from e4a4246 to d5c9e76 Compare September 5, 2022 18:29

JohnCSimon closed this Nov 27, 2022

rustbot added the S-inactive Status: Inactive and waiting on the author. This is often applied to closed PRs. label Nov 27, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

const_prop_lint: Consider array length constant even if array is not #100160

const_prop_lint: Consider array length constant even if array is not #100160

TheWastl commented Aug 5, 2022

rust-highfive commented Aug 5, 2022

rustbot commented Aug 5, 2022

compiler-errors commented Aug 5, 2022

RalfJung commented Aug 5, 2022

wesleywiser Aug 5, 2022

oli-obk Aug 25, 2022

oli-obk commented Aug 25, 2022

bors commented Aug 25, 2022

JohnTitor commented Aug 26, 2022

rustbot commented Sep 5, 2022

rust-log-analyzer commented Sep 5, 2022

JohnCSimon commented Oct 2, 2022

bors commented Oct 8, 2022

JohnCSimon commented Nov 27, 2022

const_prop_lint: Consider array length constant even if array is not #100160

const_prop_lint: Consider array length constant even if array is not #100160

Conversation

TheWastl commented Aug 5, 2022

rust-highfive commented Aug 5, 2022

rustbot commented Aug 5, 2022

compiler-errors commented Aug 5, 2022

RalfJung commented Aug 5, 2022

wesleywiser Aug 5, 2022

Choose a reason for hiding this comment

oli-obk Aug 25, 2022

Choose a reason for hiding this comment

oli-obk commented Aug 25, 2022

bors commented Aug 25, 2022

JohnTitor commented Aug 26, 2022

rustbot commented Sep 5, 2022

rust-log-analyzer commented Sep 5, 2022

JohnCSimon commented Oct 2, 2022

bors commented Oct 8, 2022

JohnCSimon commented Nov 27, 2022