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Don't build format string suggestions from concat! offsets - #163368

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h-kurashina:fix-156101
Oct 1, 2026
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Don't build format string suggestions from concat! offsets#163368
rust-bors[bot] merged 1 commit into
rust-lang:mainfrom
h-kurashina:fix-156101

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@h-kurashina h-kurashina commented Sep 26, 2026 •
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Fixes #156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by concat!, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the RemoveRawIdent suggestion already
check is_source_literal before calling fmt_span.from_inner, but the
UsePositional, ReorderFormatParameter and AddMissingColon
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change UsePositional took at! from the
concat! invocation as the captured argument, replaced it with 0,
and suggested passing at! as an argument:

help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);

The crash test is moved to tests/ui/fmt, with cases covering each of
these suggestions.

@hina-kura49
Don't build format string suggestions from concat! offsets
8c3ae60 
When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
@rustbot

rustbot commented Sep 26, 2026

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This PR changes a file inside tests/crashes. If a crash was fixed, please move into the corresponding ui subdir and add 'Fixes #' to the PR description to autoclose the issue upon merge.

@rustbot rustbot added 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 Sep 26, 2026
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Thanks for the pull request, and welcome! The Rust Project has assigned @Enselic (or someone else) to review your changes, you should hear from them (or someone else) within the next two weeks.

Please see the contribution instructions and our LLM policy for more information.

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@h-kurashina h-kurashina mentioned this pull request Sep 26, 2026
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mejrs
mejrs approved these changes Sep 30, 2026
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r? me @bors r+ rollup

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📌 Commit 8c3ae60 has been approved by mejrs

It is now in the queue for this repository.

@rust-bors rust-bors Bot added the S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. label Sep 30, 2026
@rust-bors rust-bors Bot removed the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Sep 30, 2026
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Sep 30, 2026
@JonathanBrouwer
Rollup merge of rust-lang#163368 - h-kurashina:fix-156101, r=mejrs
54dd252 
Don't build format string suggestions from `concat!` offsets

Fixes rust-lang#156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change `UsePositional` took `at!` from the
`concat!` invocation as the captured argument, replaced it with `0`,
and suggested passing `at!` as an argument:

```
help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);
```

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
@JonathanBrouwer JonathanBrouwer mentioned this pull request Sep 30, 2026
Closed
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Sep 30, 2026
@JonathanBrouwer
Rollup merge of rust-lang#163368 - h-kurashina:fix-156101, r=mejrs
f1d5136 
Don't build format string suggestions from `concat!` offsets

Fixes rust-lang#156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change `UsePositional` took `at!` from the
`concat!` invocation as the captured argument, replaced it with `0`,
and suggested passing `at!` as an argument:

```
help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);
```

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
@JonathanBrouwer JonathanBrouwer mentioned this pull request Sep 30, 2026
Closed
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Sep 30, 2026
@JonathanBrouwer
Rollup merge of rust-lang#163368 - h-kurashina:fix-156101, r=mejrs
887315a 
Don't build format string suggestions from `concat!` offsets

Fixes rust-lang#156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change `UsePositional` took `at!` from the
`concat!` invocation as the captured argument, replaced it with `0`,
and suggested passing `at!` as an argument:

```
help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);
```

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
@JonathanBrouwer JonathanBrouwer mentioned this pull request Sep 30, 2026
Closed
rust-bors Bot pushed a commit that referenced this pull request Sep 30, 2026
@bors
Auto merge of #163560 - JonathanBrouwer:rollup-i6jC441, r=JonathanBro…
12127cc 
…uwer

Rollup of 18 pull requests

Successful merges:

 - #163532 (rustc_codegen_cranelift subtree update)
 - #163534 (miri subtree update)
 - #163279 (const and NonZero impl for clamp_magnitude())
 - #162900 (Some refactorings around metadata encoding)
 - #163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - #163483 (Bump bootstrap compiler to 1.100.0 beta)
 - #159798 (Attribute documentation for cfg_attr)
 - #163368 (Don't build format string suggestions from `concat!` offsets)
 - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - #163405 (Remove some #[linkage] options)
 - #163470 (Miscellaneous attr error stuff)
 - #163489 (expose Rc::is_unique)
 - #163492 (x86 and x86_64: cleanup some callconv code)
 - #163496 (cycle handling: mirror old solver)
 - #163509 (Use more default field values in `Resolver`)
 - #163519 (Forbid  `Reborrow` impls for types with destructors)
 - #163520 (Cast cleanups)
 - #163524 (Document `Result` case for the `arena_cache` query modifier)

Failed merges:

 - #163547 ([beta] rustfmt backport)
JonathanBrouwer added a commit to JonathanBrouwer/rust that referenced this pull request Sep 30, 2026
@JonathanBrouwer
Rollup merge of rust-lang#163368 - h-kurashina:fix-156101, r=mejrs
7c94ee0 
Don't build format string suggestions from `concat!` offsets

Fixes rust-lang#156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change `UsePositional` took `at!` from the
`concat!` invocation as the captured argument, replaced it with `0`,
and suggested passing `at!` as an argument:

```
help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);
```

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
@JonathanBrouwer JonathanBrouwer mentioned this pull request Sep 30, 2026
Closed
rust-bors Bot pushed a commit that referenced this pull request Sep 30, 2026
@bors
Auto merge of #163566 - JonathanBrouwer:rollup-UyBYK1C, r=JonathanBro…
a2c44a3 
…uwer

Rollup of 18 pull requests

Successful merges:

 - #163532 (rustc_codegen_cranelift subtree update)
 - #163534 (miri subtree update)
 - #163279 (const and NonZero impl for clamp_magnitude())
 - #162900 (Some refactorings around metadata encoding)
 - #163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - #159798 (Attribute documentation for cfg_attr)
 - #162921 (make mips64 `Complex` GCC-compatible)
 - #163368 (Don't build format string suggestions from `concat!` offsets)
 - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - #163405 (Remove some #[linkage] options)
 - #163470 (Miscellaneous attr error stuff)
 - #163489 (expose Rc::is_unique)
 - #163492 (x86 and x86_64: cleanup some callconv code)
 - #163496 (cycle handling: mirror old solver)
 - #163509 (Use more default field values in `Resolver`)
 - #163519 (Forbid  `Reborrow` impls for types with destructors)
 - #163520 (Cast cleanups)
 - #163524 (Document `Result` case for the `arena_cache` query modifier)
rust-bors Bot pushed a commit that referenced this pull request Sep 30, 2026
@bors
Auto merge of #163566 - JonathanBrouwer:rollup-UyBYK1C, r=JonathanBro…
103837a 
…uwer

Rollup of 18 pull requests

Successful merges:

 - #163532 (rustc_codegen_cranelift subtree update)
 - #163534 (miri subtree update)
 - #163279 (const and NonZero impl for clamp_magnitude())
 - #162900 (Some refactorings around metadata encoding)
 - #163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - #159798 (Attribute documentation for cfg_attr)
 - #162921 (make mips64 `Complex` GCC-compatible)
 - #163368 (Don't build format string suggestions from `concat!` offsets)
 - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - #163405 (Remove some #[linkage] options)
 - #163470 (Miscellaneous attr error stuff)
 - #163489 (expose Rc::is_unique)
 - #163492 (x86 and x86_64: cleanup some callconv code)
 - #163496 (cycle handling: mirror old solver)
 - #163509 (Use more default field values in `Resolver`)
 - #163519 (Forbid  `Reborrow` impls for types with destructors)
 - #163520 (Cast cleanups)
 - #163524 (Document `Result` case for the `arena_cache` query modifier)
@jhpratt jhpratt mentioned this pull request Oct 1, 2026
Merged
rust-bors Bot pushed a commit that referenced this pull request Oct 1, 2026
@bors
Auto merge of #163583 - jhpratt:rollup-KbTrszs, r=jhpratt
837b18a 
Rollup of 20 pull requests

Successful merges:

 - #163279 (const and NonZero impl for clamp_magnitude())
 - #163081 (Provide more context on "not general enough" error)
 - #163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - #159798 (Attribute documentation for cfg_attr)
 - #162921 (make mips64 `Complex` GCC-compatible)
 - #163368 (Don't build format string suggestions from `concat!` offsets)
 - #163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - #163470 (Miscellaneous attr error stuff)
 - #163489 (expose Rc::is_unique)
 - #163492 (x86 and x86_64: cleanup some callconv code)
 - #163496 (cycle handling: mirror old solver)
 - #163509 (Use more default field values in `Resolver`)
 - #163519 (Forbid  `Reborrow` impls for types with destructors)
 - #163520 (Cast cleanups)
 - #163524 (Document `Result` case for the `arena_cache` query modifier)
 - #163546 (PassWrapper: adapt for new PassPlugin load method)
 - #163551 (Add libs-nominated triagebot config)
 - #163559 (Suggest `#[unsafe(no_mangle)]` for entry points in `no_std` binaries)
 - #163564 (rustc-dev-guide subtree update)
 - #163568 (remove dead cfg_select! arm)
@rust-bors
rust-bors Bot merged commit 3ea0d1e into rust-lang:main Oct 1, 2026
13 checks passed
@rustbot rustbot added this to the 1.101.0 milestone Oct 1, 2026
rust-bors Bot pushed a commit that referenced this pull request Oct 1, 2026
@bors
Unrolled build for #163368 in rollup 163583
8b74d06 
Rollup merge of #163368 - h-kurashina:fix-156101, r=mejrs

Don't build format string suggestions from `concat!` offsets

Fixes #156101

When a format string does not come directly from a string literal in
the source, e.g. when it is produced by `concat!`, the parser's inner
offsets are relative to the expanded string rather than to the source.
The primary error span and the `RemoveRawIdent` suggestion already
check `is_source_literal` before calling `fmt_span.from_inner`, but the
`UsePositional`, `ReorderFormatParameter` and `AddMissingColon`
suggestions did not.

As a result, these suggestions could point into the middle of a
multibyte character and ICE when rendered, or suggest a bogus argument
copied from unrelated source text. Only emit them when the format
string is a source literal, like the other suggestions do.

For example, before this change `UsePositional` took `at!` from the
`concat!` invocation as the captured argument, replaced it with `0`,
and suggested passing `at!` as an argument:

```
help: consider using a positional formatting argument instead
  |
2 -     format_args!(concat!("{}{a.b}", ""));
2 +     format_args!(conc0("{}{a.b}", ""), at!);
```

The crash test is moved to `tests/ui/fmt`, with cases covering each of
these suggestions.
RalfJung pushed a commit to RalfJung/miri that referenced this pull request Oct 1, 2026
@bors
Auto merge of #163583 - jhpratt:rollup-KbTrszs, r=jhpratt
7edc483 
Rollup of 20 pull requests

Successful merges:

 - rust-lang/rust#163279 (const and NonZero impl for clamp_magnitude())
 - rust-lang/rust#163081 (Provide more context on "not general enough" error)
 - rust-lang/rust#163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - rust-lang/rust#159798 (Attribute documentation for cfg_attr)
 - rust-lang/rust#162921 (make mips64 `Complex` GCC-compatible)
 - rust-lang/rust#163368 (Don't build format string suggestions from `concat!` offsets)
 - rust-lang/rust#163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - rust-lang/rust#163470 (Miscellaneous attr error stuff)
 - rust-lang/rust#163489 (expose Rc::is_unique)
 - rust-lang/rust#163492 (x86 and x86_64: cleanup some callconv code)
 - rust-lang/rust#163496 (cycle handling: mirror old solver)
 - rust-lang/rust#163509 (Use more default field values in `Resolver`)
 - rust-lang/rust#163519 (Forbid  `Reborrow` impls for types with destructors)
 - rust-lang/rust#163520 (Cast cleanups)
 - rust-lang/rust#163524 (Document `Result` case for the `arena_cache` query modifier)
 - rust-lang/rust#163546 (PassWrapper: adapt for new PassPlugin load method)
 - rust-lang/rust#163551 (Add libs-nominated triagebot config)
 - rust-lang/rust#163559 (Suggest `#[unsafe(no_mangle)]` for entry points in `no_std` binaries)
 - rust-lang/rust#163564 (rustc-dev-guide subtree update)
 - rust-lang/rust#163568 (remove dead cfg_select! arm)
@github-actions github-actions Bot mentioned this pull request Oct 3, 2026
Draft
github-actions Bot pushed a commit to rust-lang/rustc-dev-guide that referenced this pull request Oct 5, 2026
@bors
Auto merge of #163583 - jhpratt:rollup-KbTrszs, r=jhpratt
25525fb 
Rollup of 20 pull requests

Successful merges:

 - rust-lang/rust#163279 (const and NonZero impl for clamp_magnitude())
 - rust-lang/rust#163081 (Provide more context on "not general enough" error)
 - rust-lang/rust#163455 (Don't use the metadata based crate_hash for rustdoc runs)
 - rust-lang/rust#159798 (Attribute documentation for cfg_attr)
 - rust-lang/rust#162921 (make mips64 `Complex` GCC-compatible)
 - rust-lang/rust#163368 (Don't build format string suggestions from `concat!` offsets)
 - rust-lang/rust#163375 (Update expect messages in library/std/src/os/unix/net/ following Rust's `expect` guidance)
 - rust-lang/rust#163470 (Miscellaneous attr error stuff)
 - rust-lang/rust#163489 (expose Rc::is_unique)
 - rust-lang/rust#163492 (x86 and x86_64: cleanup some callconv code)
 - rust-lang/rust#163496 (cycle handling: mirror old solver)
 - rust-lang/rust#163509 (Use more default field values in `Resolver`)
 - rust-lang/rust#163519 (Forbid  `Reborrow` impls for types with destructors)
 - rust-lang/rust#163520 (Cast cleanups)
 - rust-lang/rust#163524 (Document `Result` case for the `arena_cache` query modifier)
 - rust-lang/rust#163546 (PassWrapper: adapt for new PassPlugin load method)
 - rust-lang/rust#163551 (Add libs-nominated triagebot config)
 - rust-lang/rust#163559 (Suggest `#[unsafe(no_mangle)]` for entry points in `no_std` binaries)
 - rust-lang/rust#163564 (rustc-dev-guide subtree update)
 - rust-lang/rust#163568 (remove dead cfg_select! arm)
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[ICE]: assertion failed: bpos.to_u32() >= mbc.pos.to_u32() + mbc.bytes as u32

5 participants

@h-kurashina @rustbot @mejrs @Enselic @hina-kura49