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test(fix): verify cargo might fix into rust-src
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The suggestion is slightly tweaked since the original
diagnostic was rejected due to multiple files were involved.

For the original diagnostic JSON, see
rust-lang/rust#88514 (comment)
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@weihanglo
weihanglo committed Apr 23, 2024
1 parent d29ad67 commit 8410c1e
Showing 1 changed file with 374 additions and 0 deletions.
374 changes: 374 additions & 0 deletions tests/testsuite/fix.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1906,6 +1906,380 @@ warning: `foo` (lib) generated 1 warning (run `cargo fix --lib -p foo` to apply
.run();
}

#[cargo_test]
fn fix_in_rust_src() {
// Tests what happens if rustc emits a suggestion to modify the standard
// library in rust source. This should never happen, and indicates a bug in
// rustc. However, there are several known bugs in rustc where it does this
// (often involving macros), so `cargo fix` has a guard that says if the
// suggestion points to rust source under sysroot to not apply it.
//
// See https://github.com/rust-lang/cargo/issues/9857 for some other
// examples.
//
// This test uses a simulated rustc which replays a suggestion via a JSON
// message that points into rust-src. This does not use the real rustc
// because as the bugs are fixed in the real rustc, that would cause this
// test to stop working.

let p = project()
.file(
"Cargo.toml",
r#"
[package]
name = "foo"
edition = "2021"
"#,
)
.file(
"src/lib.rs",
r#"
pub fn bug_report<W: std::fmt::Write>(w: &mut W) -> std::fmt::Result {
if true {
writeln!(w, "`;?` here ->")?;
} else {
writeln!(w, "but not here")
}
Ok(())
}
"#,
)
.build();
p.cargo("fetch").run();

// Since this is a substitution into a Rust string (representing a JSON
// string), deal with backslashes like on Windows.
let sysroot = paths::sysroot().replace("\\", "/");

// This is a fake rustc that will emit a JSON message when the `foo` crate
// builds that tells cargo to modify a file it shouldn't.
let rustc = project()
.at("rustc-replay")
.file("Cargo.toml", &basic_manifest("rustc-replay", "1.0.0"))
.file("src/main.rs",
&r##"
fn main() {
let pkg_name = match std::env::var("CARGO_PKG_NAME") {
Ok(pkg_name) => pkg_name,
Err(_) => {
let r = std::process::Command::new("rustc")
.args(std::env::args_os().skip(1))
.status();
std::process::exit(r.unwrap().code().unwrap_or(2));
}
};
if pkg_name == "foo" {
eprintln!("{}", r#"{
"$message_type": "diagnostic",
"message": "mismatched types",
"code":
{
"code": "E0308",
"explanation": "Expected type did not match the received type.\n\nErroneous code examples:\n\n```compile_fail,E0308\nfn plus_one(x: i32) -> i32 {\n x + 1\n}\n\nplus_one(\"Not a number\");\n// ^^^^^^^^^^^^^^ expected `i32`, found `&str`\n\nif \"Not a bool\" {\n// ^^^^^^^^^^^^ expected `bool`, found `&str`\n}\n\nlet x: f32 = \"Not a float\";\n// --- ^^^^^^^^^^^^^ expected `f32`, found `&str`\n// |\n// expected due to this\n```\n\nThis error occurs when an expression was used in a place where the compiler\nexpected an expression of a different type. It can occur in several cases, the\nmost common being when calling a function and passing an argument which has a\ndifferent type than the matching type in the function declaration.\n"
},
"level": "error",
"spans":
[
{
"file_name": "__SYSROOT__/lib/rustlib/src/rust/library/core/src/macros/mod.rs",
"byte_start": 23568,
"byte_end": 23617,
"line_start": 670,
"line_end": 670,
"column_start": 9,
"column_end": 58,
"is_primary": true,
"text":
[
{
"text": " $dst.write_fmt($crate::format_args_nl!($($arg)*))",
"highlight_start": 9,
"highlight_end": 58
}
],
"label": "expected `()`, found `Result<(), Error>`",
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion":
{
"span":
{
"file_name": "lib.rs",
"byte_start": 144,
"byte_end": 171,
"line_start": 5,
"line_end": 5,
"column_start": 9,
"column_end": 36,
"is_primary": false,
"text":
[
{
"text": " writeln!(w, \"but not here\")",
"highlight_start": 9,
"highlight_end": 36
}
],
"label": null,
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion": null
},
"macro_decl_name": "writeln!",
"def_site_span":
{
"file_name": "__SYSROOT__/lib/rustlib/src/rust/library/core/src/macros/mod.rs",
"byte_start": 23434,
"byte_end": 23454,
"line_start": 665,
"line_end": 665,
"column_start": 1,
"column_end": 21,
"is_primary": false,
"text":
[
{
"text": "macro_rules! writeln {",
"highlight_start": 1,
"highlight_end": 21
}
],
"label": null,
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion": null
}
}
},
{
"file_name": "lib.rs",
"byte_start": 75,
"byte_end": 177,
"line_start": 2,
"line_end": 6,
"column_start": 5,
"column_end": 6,
"is_primary": false,
"text":
[
{
"text": " if true {",
"highlight_start": 5,
"highlight_end": 14
},
{
"text": " writeln!(w, \"`;?` here ->\")?;",
"highlight_start": 1,
"highlight_end": 38
},
{
"text": " } else {",
"highlight_start": 1,
"highlight_end": 13
},
{
"text": " writeln!(w, \"but not here\")",
"highlight_start": 1,
"highlight_end": 36
},
{
"text": " }",
"highlight_start": 1,
"highlight_end": 6
}
],
"label": "expected this to be `()`",
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion": null
}
],
"children":
[
{
"message": "use the `?` operator to extract the `Result<(), std::fmt::Error>` value, propagating a `Result::Err` value to the caller",
"code": null,
"level": "help",
"spans":
[
{
"file_name": "__SYSROOT__/lib/rustlib/src/rust/library/core/src/macros/mod.rs",
"byte_start": 23617,
"byte_end": 23617,
"line_start": 670,
"line_end": 670,
"column_start": 58,
"column_end": 58,
"is_primary": true,
"text":
[
{
"text": " $dst.write_fmt($crate::format_args_nl!($($arg)*))",
"highlight_start": 58,
"highlight_end": 58
}
],
"label": null,
"suggested_replacement": "?",
"suggestion_applicability": "HasPlaceholders",
"expansion":
{
"span":
{
"file_name": "lib.rs",
"byte_start": 144,
"byte_end": 171,
"line_start": 5,
"line_end": 5,
"column_start": 9,
"column_end": 36,
"is_primary": false,
"text":
[
{
"text": " writeln!(w, \"but not here\")",
"highlight_start": 9,
"highlight_end": 36
}
],
"label": null,
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion": null
},
"macro_decl_name": "writeln!",
"def_site_span":
{
"file_name": "__SYSROOT__/lib/rustlib/src/rust/library/core/src/macros/mod.rs",
"byte_start": 23434,
"byte_end": 23454,
"line_start": 665,
"line_end": 665,
"column_start": 1,
"column_end": 21,
"is_primary": false,
"text":
[
{
"text": "macro_rules! writeln {",
"highlight_start": 1,
"highlight_end": 21
}
],
"label": null,
"suggested_replacement": null,
"suggestion_applicability": null,
"expansion": null
}
}
}
],
"children":
[],
"rendered": null
}
],
"rendered": "error[E0308]: mismatched types\n --> lib.rs:5:9\n |\n2 | / if true {\n3 | | writeln!(w, \"`;?` here ->\")?;\n4 | | } else {\n5 | | writeln!(w, \"but not here\")\n | | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `Result<(), Error>`\n6 | | }\n | |_____- expected this to be `()`\n |\n = note: expected unit type `()`\n found enum `Result<(), std::fmt::Error>`\n = note: this error originates in the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)\nhelp: consider using a semicolon here\n |\n6 | };\n | +\nhelp: you might have meant to return this value\n |\n5 | return writeln!(w, \"but not here\");\n | ++++++ +\nhelp: use the `?` operator to extract the `Result<(), std::fmt::Error>` value, propagating a `Result::Err` value to the caller\n --> __SYSROOT__/lib/rustlib/src/rust/library/core/src/macros/mod.rs:670:58\n |\n67| $dst.write_fmt($crate::format_args_nl!($($arg)*))?\n | +\n\n"
}"#.replace("\n", ""));
std::process::exit(2);
}
}
"##.replace("__SYSROOT__", &sysroot))
.build();
rustc.cargo("build").run();
let rustc_bin = rustc.bin("rustc-replay");

// The output here should not say `Fixed`.
//
// It is OK to compare the full diagnostic output here because the text is
// hard-coded in rustc-replay. Normally tests should not be checking the
// compiler output.
p.cargo("fix --lib --allow-no-vcs --broken-code")
.env("__CARGO_FIX_YOLO", "1")
.env("RUSTC", &rustc_bin)
.with_status(101)
.with_stderr(r#"[CHECKING] foo v0.0.0 ([..])
[WARNING] failed to automatically apply fixes suggested by rustc to crate `foo`
after fixes were automatically applied the compiler reported errors within these files:
* [..]/lib/rustlib/src/rust/library/core/src/macros/mod.rs
* 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:
error[E0308]: mismatched types
--> lib.rs:5:9
|
2 | / if true {
3 | | writeln!(w, "`;?` here ->")?;
4 | | } else {
5 | | writeln!(w, "but not here")
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `Result<(), Error>`
6 | | }
| |_____- expected this to be `()`
|
= note: expected unit type `()`
found enum `Result<(), std::fmt::Error>`
= note: this error originates in the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider using a semicolon here
|
6 | };
| +
help: you might have meant to return this value
|
5 | return writeln!(w, "but not here");
| ++++++ +
help: use the `?` operator to extract the `Result<(), std::fmt::Error>` value, propagating a `Result::Err` value to the caller
--> [..]/lib/rustlib/src/rust/library/core/src/macros/mod.rs:670:58
|
67| $dst.write_fmt($crate::format_args_nl!($($arg)*))?
| +
Original diagnostics will follow.
error[E0308]: mismatched types
--> lib.rs:5:9
|
2 | / if true {
3 | | writeln!(w, "`;?` here ->")?;
4 | | } else {
5 | | writeln!(w, "but not here")
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `()`, found `Result<(), Error>`
6 | | }
| |_____- expected this to be `()`
|
= note: expected unit type `()`
found enum `Result<(), std::fmt::Error>`
= note: this error originates in the macro `writeln` (in Nightly builds, run with -Z macro-backtrace for more info)
help: consider using a semicolon here
|
6 | };
| +
help: you might have meant to return this value
|
5 | return writeln!(w, "but not here");
| ++++++ +
help: use the `?` operator to extract the `Result<(), std::fmt::Error>` value, propagating a `Result::Err` value to the caller
--> [..]/lib/rustlib/src/rust/library/core/src/macros/mod.rs:670:58
|
67| $dst.write_fmt($crate::format_args_nl!($($arg)*))?
| +
[ERROR] could not compile `foo` (lib) due to 1 previous error
"#)
.run();
}

// This fixes rust-lang/rust#123304.
// If that lint stops emitting duplicate suggestions,
// we might need to find a substitution.
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