rustc: improve diagnostics for file-open failures by Unique-Usman · Pull Request #158323 · rust-lang/rust

Unique-Usman · 2026-06-23T18:50:01Z

rustbot · 2026-06-23T18:50:04Z

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

rustbot · 2026-06-23T18:50:07Z

rustbot has assigned @nnethercote.
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Unique-Usman · 2026-06-23T18:56:01Z

cc: @estebank

nnethercote

Generally looks good. A couple of nits below, and I will give @estebank some more time to comment.

View changes since this review

UnkwUsr · 2026-06-24T19:06:00Z

Edge case: permission denied for directory. This PR reports "permission denied when opening file". For comparison, ls from gnu-coreutils handles such case correctly.

$ mkdir /tmp/asd
$ chmod 000 /tmp/asd
$ ./rustc /tmp/asd
error: permission denied when opening file `/tmp/asd`

error: aborting due to 1 previous error

$ ls /tmp/asd
ls: cannot open directory '/tmp/asd': Permission denied

Though for directories with access it prints an error about directory:

$ chmod 777 /tmp/asd
$ ./rustc /tmp/asd
error: `/tmp/asd` is a directory

error: aborting due to 1 previous error

estebank

Edge case: permission denied for directory. This PR reports "permission denied when opening file". For comparison, ls from gnu-coreutils handles such case correctly.

Although I agree, I would be hesitant with trying to naively improve that case because depending on how it is written, it won't be TOCTOU-safe. I feel it is ok to go with the current approach of just customizing the text from what ErrorKind is returned.

I'm happy with the changes overall.

View changes since this review

estebank · 2026-06-24T22:57:04Z

+                            parent.join(suggestion.as_str()).display().to_string()
+                        };
+                        err.help(format!(
+                            "you might have meant to open `{}`: `rustc {}`",


Let's not provide the command example because if someone is running a more complex command (even as simple as rustc foo.rs --edition=2024), we'd be suggesting the wrong thing. Just mentioning the file name should be enough (at least for now).

estebank · 2026-06-24T23:02:32Z

+        if e.kind() == ErrorKind::NotFound {
+            if let Some(file_name) = path.file_name().and_then(|n| n.to_str()) {
+                let parent =
+                    path.parent().filter(|p| !p.as_os_str().is_empty()).unwrap_or(Path::new("."));


Minor concern: is this the right way of doing this? It seems ok, but I am surprised there's no better way of doing this :)

Good point. I didn't find a dedicated helper for this case. parent() can yield an empty path for relative paths like foo.rs, and we need a directory we can iterate, so I filtered out the empty path and fell back to ".". Happy to switch to a more idiomatic approach if there's one I'm missing.

What of this ?

let parent = match path.parent() { Some(p) if !p.as_os_str().is_empty() => p, _ => Path::new("."), };

nnethercote · 2026-06-29T10:49:27Z

@bors r+ rollup

rust-bors · 2026-06-29T10:49:30Z

📌 Commit a13e2da has been approved by nnethercote

It is now in the queue for this repository.

…e, r=nnethercote rustc: improve diagnostics for file-open failures Fix: [rust-lang#156070](rust-lang#156070)

Rollup of 6 pull requests Successful merges: - #158073 (bootstrap: fix panic when repo path contains spaces by switching to CARGO_ENCODED_RUSTFLAGS) - #158256 (Avoid parser panics bubbling out to proc macros) - #158081 (trait-system: Recover deferred closure calls after errors) - #158323 (rustc: improve diagnostics for file-open failures) - #158327 (Move attribute and keyword docs from `std` to `core`) - #158468 (Include default-stability info in rustdoc JSON.)

jhpratt · 2026-06-29T16:38:18Z

@bor r-

#158558 (comment)

jhpratt · 2026-06-29T16:38:31Z

@bors r-

rust-bors · 2026-06-29T16:38:39Z

This pull request was unapproved.

This PR was contained in a rollup (#158558), which was unapproved.

View changes since this unapproval

Emit more targeted diagnostics when an input file cannot be opened, including dedicated messages for common error kinds and typo suggestions for missing files. Add run-make tests covering NotFound, PermissionDenied, IsADirectory, and non-existent directory cases. Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>

rust-log-analyzer · 2026-06-29T22:46:26Z

The job aarch64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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

---- [ui] tests/ui/modules/path-no-file-name.rs stdout ----
Saved the actual stderr to `/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/modules/path-no-file-name/path-no-file-name.stderr`
diff of stderr:

- error: permission denied when opening file `$DIR/.`
+ error: `$DIR/.` is a directory
2   --> $DIR/path-no-file-name.rs:5:1
3    |
4 LL | mod m;

Note: some mismatched output was normalized before being compared
- error: `/checkout/tests/ui/modules/.` is a directory
-   --> /checkout/tests/ui/modules/path-no-file-name.rs:5:1
+ error: `$DIR/.` is a directory


The actual stderr differed from the expected stderr
To update references, rerun the tests and pass the `--bless` flag
To only update this specific test, also pass `--test-args modules/path-no-file-name.rs`

error: 1 errors occurred comparing output.
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/modules/path-no-file-name.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/aarch64-unknown-linux-gnu/stage2" "--target=aarch64-unknown-linux-gnu" "--check-cfg" "cfg(test,FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/aarch64-unknown-linux-gnu/test/ui/modules/path-no-file-name" "-A" "unused" "-W" "unused_attributes" "-A" "internal_features" "-A" "incomplete_features" "-A" "unused_parens" "-A" "unused_braces" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/aarch64-unknown-linux-gnu/native/rust-test-helpers"
stdout: none
--- stderr -------------------------------
error: `/checkout/tests/ui/modules/.` is a directory
##[error]  --> /checkout/tests/ui/modules/path-no-file-name.rs:5:1
   |
LL | mod m; //~ ERROR couldn't read
   | ^^^^^^

error: aborting due to 1 previous error
------------------------------------------

estebank · 2026-06-29T23:13:16Z

You will have to change the test to have two flavors, one for windows and one for linux (so you'll end up with two different stderr files), as well as remove the comments in the test that rewrite the stderr output.

rustbot added A-run-make Area: port run-make Makefiles to rmake.rs 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 Jun 23, 2026

rustbot assigned nnethercote Jun 23, 2026

nnethercote reviewed Jun 24, 2026

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Comment thread compiler/rustc_parse/src/lib.rs Outdated

Comment thread compiler/rustc_parse/src/lib.rs Outdated

Comment thread tests/run-make/input-file-errors/rmake.rs Outdated

Unique-Usman requested a review from nnethercote June 24, 2026 07:25

Unique-Usman force-pushed the ua/invalid_source_file branch from dae50a7 to 2f4edae Compare June 24, 2026 08:22

estebank approved these changes Jun 24, 2026

View reviewed changes

Unique-Usman force-pushed the ua/invalid_source_file branch from 2f4edae to a13e2da Compare June 25, 2026 17:54

Unique-Usman requested a review from estebank June 25, 2026 22:11

nnethercote approved these changes Jun 29, 2026

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rust-bors Bot 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 Jun 29, 2026

jhpratt added a commit to jhpratt/rust that referenced this pull request Jun 29, 2026

Rollup merge of rust-lang#158323 - Unique-Usman:ua/invalid_source_fil…

8148b29

…e, r=nnethercote rustc: improve diagnostics for file-open failures Fix: [rust-lang#156070](rust-lang#156070)

jhpratt mentioned this pull request Jun 29, 2026

Rollup of 6 pull requests #158558

Closed

rust-bors Bot 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 Jun 29, 2026

Unique-Usman force-pushed the ua/invalid_source_file branch from a13e2da to b81e3b2 Compare June 29, 2026 21:59

Unique-Usman force-pushed the ua/invalid_source_file branch from b81e3b2 to f3e42b9 Compare June 29, 2026 22:05

Unique-Usman requested a review from nnethercote June 29, 2026 22:12

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jun 29, 2026

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