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fix(fix): Switch from ad-hoc to structured warnings #16711

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Merged
weihanglo merged 1 commit into from
Mar 6, 2026
+92 −139
Merged

fix(fix): Switch from ad-hoc to structured warnings #16711

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107 changes: 48 additions & 59 deletions src/cargo/util/diagnostic_server.rs
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,14 +2,16 @@
//! cross-platform way for the `cargo fix` command.

use std::collections::HashSet;
use std::fmt::Write as _;
use std::io::{BufReader, Read, Write};
use std::net::{Shutdown, SocketAddr, TcpListener, TcpStream};
use std::path::PathBuf;
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, Ordering};
use std::thread::{self, JoinHandle};

use annotate_snippets::Group;
use annotate_snippets::Level;
use annotate_snippets::Origin;
use anyhow::{Context as _, Error};
use cargo_util::ProcessBuilder;
use serde::{Deserialize, Serialize};
Expand Down Expand Up @@ -128,15 +130,15 @@ impl<'a> DiagnosticPrinter<'a> {
Message::ReplaceFailed { file, message } => {
let issue_link = get_bug_report_url(self.workspace_wrapper);

let mut msg = format!("error applying suggestions to `{file}`\n");
writeln!(&mut msg)?;
writeln!(&mut msg, "The full error message was:")?;
writeln!(&mut msg)?;
writeln!(&mut msg, "> {message}")?;
writeln!(&mut msg)?;
writeln!(&mut msg, "{}", gen_please_report_this_bug_text(issue_link))?;
writeln!(&mut msg, "{}", gen_suggest_broken_code())?;
self.gctx.shell().warn(&msg)?;
let report = &[
Level::ERROR
.secondary_title("error applying suggestions")
.element(Origin::path(file))
.element(Level::ERROR.with_name("cause").message(message)),
gen_please_report_this_bug_group(issue_link),
gen_suggest_broken_code_group(),
];
self.gctx.shell().print_report(report, false)?;
Ok(())
}
Message::FixFailed {
Expand All @@ -152,42 +154,34 @@ impl<'a> DiagnosticPrinter<'a> {
};
let issue_link = get_bug_report_url(self.workspace_wrapper);

let mut msg =
format!("failed to automatically apply fixes suggested by rustc{to_crate}\n");
if !files.is_empty() {
writeln!(&mut msg)?;
writeln!(
&mut msg,
"after fixes were automatically applied the compiler \
reported errors within these files:"
)?;
writeln!(&mut msg)?;
for file in files {
writeln!(&mut msg, " * {file}")?;
}
writeln!(&mut msg)?;
}
write!(
&mut msg,
"{}\n",
gen_please_report_this_bug_text(issue_link)
)?;
write!(&mut msg, "{}\n\n", gen_suggest_broken_code())?;
if !errors.is_empty() {
writeln!(&mut msg, "The following errors were reported:")?;
for error in errors {
write!(&mut msg, "{error}")?;
if !error.ends_with('\n') {
writeln!(&mut msg)?;
}
}
}
if let Some(exit) = abnormal_exit {
writeln!(&mut msg, "rustc exited abnormally: {exit}")?;
}
writeln!(&mut msg, "Original diagnostics will follow.")?;
let cause_message = if !errors.is_empty() {
Some(errors.join("\n").trim().to_owned())
} else {
None
};

let report = &[
Level::ERROR
.secondary_title(format!("errors present after applying fixes{to_crate}"))
.elements(files.iter().map(|f| Origin::path(f)))
.elements(
cause_message
.into_iter()
.map(|err| Level::ERROR.with_name("cause").message(err)),
)
.elements(abnormal_exit.iter().map(|exit| {
Level::ERROR
.with_name("cause")
.message(format!("rustc exited abnormally: {exit}"))
})),
gen_please_report_this_bug_group(issue_link),
gen_suggest_broken_code_group(),
Group::with_title(
Level::NOTE.secondary_title("original diagnostics will follow:"),
),
];

self.gctx.shell().warn(&msg)?;
self.gctx.shell().print_report(report, false)?;
Ok(())
}
Message::EditionAlreadyEnabled { message, edition } => {
Expand Down Expand Up @@ -223,22 +217,17 @@ https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-proje
}
}

fn gen_please_report_this_bug_text(url: &str) -> String {
format!(
"This likely indicates a bug in either rustc or cargo itself,\n\
and we would appreciate a bug report! You're likely to see\n\
a number of compiler warnings after this message which cargo\n\
attempted to fix but failed. If you could open an issue at\n\
{url}\n\
quoting the full output of this command we'd be very appreciative!\
",
)
fn gen_please_report_this_bug_group(url: &str) -> Group<'static> {
Group::with_title(Level::HELP.secondary_title(format!(
"to report this as a bug, open an issue at {url}, quoting the full output of this command"
)))
}

fn gen_suggest_broken_code() -> &'static str {
"Note that you may be able to make some more progress in the near-term\n\
fixing code with the `--broken-code` flag\
"
fn gen_suggest_broken_code_group() -> Group<'static> {
Group::with_title(
Level::HELP
.secondary_title("to possibly apply more fixes, pass in the `--broken-code` flag"),
)
}

fn get_bug_report_url(rustc_workspace_wrapper: &Option<PathBuf>) -> &str {
Expand Down
29 changes: 21 additions & 8 deletions tests/testsuite/fix.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1429,9 +1429,17 @@ fn fix_to_broken_code() {
.cwd("bar")
.env("RUSTC", p.root().join("foo/target/debug/foo"))
.with_stderr_data(str![[r#"
[COMPILING] bar v0.1.0 ([ROOT]/foo/bar)
[ERROR] errors present after applying fixes to crate `bar`
|
= cause: thread 'main' ([..]) panicked at src/main.rs:23:29:
explicit panic
[NOTE] run with `RUST_BACKTRACE=1` environment variable to display a backtrace
[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[NOTE] original diagnostics will follow:
...
[WARNING] failed to automatically apply fixes suggested by rustc to crate `bar`
...

"#]])
.run();

Expand Down Expand Up @@ -1772,13 +1780,18 @@ fn abnormal_exit() {
)
// "signal: 6, SIGABRT: process abort signal" on some platforms
.with_stderr_data(str![[r#"
[LOCKING] 1 package to latest compatible version
[COMPILING] pm v0.1.0 ([ROOT]/foo/pm)
[CHECKING] foo v0.1.0 ([ROOT]/foo)
[ERROR] errors present after applying fixes to crate `foo`
|
= cause: I'm not a diagnostic.
= cause: rustc exited abnormally: [..]
[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[NOTE] original diagnostics will follow:
...
[WARNING] failed to automatically apply fixes suggested by rustc to crate `foo`
...
I'm not a diagnostic.
rustc exited abnormally: [..]
Original diagnostics will follow.
...

"#]])
.run();
}
Expand Down
95 changes: 23 additions & 72 deletions tests/testsuite/fix_n_times.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -327,21 +327,11 @@ fn fix_overlapping_max() {
|_execs| {},
str![[r#"
[CHECKING] foo v0.0.1 ([ROOT]/foo)
[WARNING] error applying suggestions to `src/lib.rs`

The full error message was:

> cannot replace slice of data that was already replaced

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

[ERROR] error applying suggestions
--> src/lib.rs
= cause: cannot replace slice of data that was already replaced
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@weihanglo weihanglo Mar 6, 2026

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(not a blocker)

Is cause: a convention?

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@epage epage Mar 6, 2026

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Nope

[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[FIXED] src/lib.rs (4 fixes)
rustc fix shim comment 5
rustc fix shim comment 6
Expand All @@ -362,25 +352,12 @@ fn fix_verification_failed() {
|_execs| {},
str![[r#"
[CHECKING] foo v0.0.1 ([ROOT]/foo)
[WARNING] failed to automatically apply fixes suggested by rustc to crate `foo`

after fixes were automatically applied the compiler reported errors within these files:

* src/lib.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
rustc fix shim error count=2
Original diagnostics will follow.

[ERROR] errors present after applying fixes to crate `foo`
--> src/lib.rs
= cause: rustc fix shim error count=2
[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[NOTE] original diagnostics will follow:
rustc fix shim comment 1
[WARNING] `foo` (lib) generated 1 warning (run `cargo fix --lib -p foo` to apply 1 suggestion)
[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
Expand All @@ -402,25 +379,12 @@ fn fix_verification_failed_clippy() {
},
str![[r#"
[CHECKING] foo v0.0.1 ([ROOT]/foo)
[WARNING] failed to automatically apply fixes suggested by rustc to crate `foo`

after fixes were automatically applied the compiler reported errors within these files:

* src/lib.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust-clippy/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
rustc fix shim error count=2
Original diagnostics will follow.

[ERROR] errors present after applying fixes to crate `foo`
--> src/lib.rs
= cause: rustc fix shim error count=2
[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust-clippy/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[NOTE] original diagnostics will follow:
rustc fix shim comment 1
[WARNING] `foo` (lib) generated 1 warning (run `cargo clippy --fix --lib -p foo` to apply 1 suggestion)
[FINISHED] `dev` profile [unoptimized + debuginfo] target(s) in [ELAPSED]s
Expand Down Expand Up @@ -493,25 +457,12 @@ fn broken_code_one_suggestion() {
},
str![[r#"
[CHECKING] foo v0.0.1 ([ROOT]/foo)
[WARNING] failed to automatically apply fixes suggested by rustc to crate `foo`

after fixes were automatically applied the compiler reported errors within these files:

* src/lib.rs

This likely indicates a bug in either rustc or cargo itself,
and we would appreciate a bug report! You're likely to see
a number of compiler warnings after this message which cargo
attempted to fix but failed. If you could open an issue at
https://github.com/rust-lang/rust/issues
quoting the full output of this command we'd be very appreciative!
Note that you may be able to make some more progress in the near-term
fixing code with the `--broken-code` flag

The following errors were reported:
rustc fix shim error count=2
Original diagnostics will follow.

[ERROR] errors present after applying fixes to crate `foo`
--> src/lib.rs
= cause: rustc fix shim error count=2
[HELP] to report this as a bug, open an issue at https://github.com/rust-lang/rust/issues, quoting the full output of this command
[HELP] to possibly apply more fixes, pass in the `--broken-code` flag
[NOTE] original diagnostics will follow:
rustc fix shim comment 1
rustc fix shim error count=2
[WARNING] `foo` (lib) generated 1 warning
Expand Down