Improve format string errors #50610
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Improve format string errors #50610
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- Point at format string position inside the formatting string - Explain that argument names can't start with an underscore
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Improve format string errors
Point at format string position inside the formatting string:
```
error: invalid format string: unmatched `}` found
--> $DIR/format-string-error.rs:21:22
|
LL | let _ = format!("}");
| ^ unmatched `}` in format string
```
Explain that argument names can't start with an underscore:
```
error: invalid format string: invalid argument name `_foo`
--> $DIR/format-string-error.rs:15:23
|
LL | let _ = format!("{_foo}", _foo = 6usize);
| ^^^^ invalid argument name in format string
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= note: argument names cannot start with an underscore
```
Fix #23476.
The more accurate spans will only be seen when using `format!` directly, when using `println!` the diagnostics machinery makes the span be the entire statement.
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💔 Test failed - status-travis |
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May 17, 2018
Improve format string errors
Point at format string position inside the formatting string:
```
error: invalid format string: unmatched `}` found
--> $DIR/format-string-error.rs:21:22
|
LL | let _ = format!("}");
| ^ unmatched `}` in format string
```
Explain that argument names can't start with an underscore:
```
error: invalid format string: invalid argument name `_foo`
--> $DIR/format-string-error.rs:15:23
|
LL | let _ = format!("{_foo}", _foo = 6usize);
| ^^^^ invalid argument name in format string
|
= note: argument names cannot start with an underscore
```
Fix rust-lang#23476.
The more accurate spans will only be seen when using `format!` directly, when using `println!` the diagnostics machinery makes the span be the entire statement.
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May 18, 2018
Rollup of 10 pull requests Successful merges: - #50387 (Remove leftover tab in libtest outputs) - #50553 (Add Option::xor method) - #50610 (Improve format string errors) - #50649 (Tweak `nearest_common_ancestor()`.) - #50790 (Fix grammar documentation wrt Unicode identifiers) - #50791 (Fix null exclusions in grammar docs) - #50806 (Add `bless` x.py subcommand for easy ui test replacement) - #50818 (Speed up `opt_normalize_projection_type`) - #50837 (Revert #49767) - #50839 (Make sure people know the book is free oline) Failed merges:
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Nov 28, 2019
Previously:
error: invalid format string: invalid argument name `_x`
--> src/main.rs:2:16
|
2 | println!("{_x}", a=0);
| ^^ invalid argument name in format string
|
= note: argument names cannot start with an underscore
Not supporting identifiers starting with underscore appears to have been
an arbitrary limitation from 2013 in code that was most likely never
reviewed:
https://github.com/rust-lang/rust/pull/8245/files#diff-0347868ef389c805e97636623e4a4ea6R277
The error message was dutifully improved in rust-lang#50610 but is there any
reason that leading underscore would be a special case?
This commit updates the format_args parser to accept identifiers with
leading underscores.
dtolnay
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Nov 30, 2019
Allow any identifier as format arg name
Previously:
```console
error: invalid format string: invalid argument name `_x`
--> src/main.rs:2:16
|
2 | println!("{_x}", _x=0);
| ^^ invalid argument name in format string
|
= note: argument names cannot start with an underscore
```
Not supporting identifiers starting with underscore appears to have been an arbitrary limitation from 2013 in code that was most likely never reviewed: https://github.com/rust-lang/rust/pull/8245/files#diff-0347868ef389c805e97636623e4a4ea6R277
The error message was dutifully improved in rust-lang#50610 but is there any reason that leading underscore would be a special case?
This commit updates the format_args parser to accept identifiers with leading underscores.
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Point at format string position inside the formatting string:
Explain that argument names can't start with an underscore:
Fix #23476.
The more accurate spans will only be seen when using
format!directly, when usingprintln!the diagnostics machinery makes the span be the entire statement.