423a5d3e85
Previously:
error: invalid format string: invalid argument name `_x`
--> src/main.rs:2:16
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2 | println!("{_x}", a=0);
| ^^ invalid argument name in format string
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= 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 #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.
56 lines
1.3 KiB
Rust
56 lines
1.3 KiB
Rust
// ignore-tidy-tab
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fn main() {
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println!("{");
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//~^ ERROR invalid format string: expected `'}'` but string was terminated
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println!("{{}}");
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println!("}");
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//~^ ERROR invalid format string: unmatched `}` found
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let _ = format!("{_}", _ = 6usize);
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//~^ ERROR invalid format string: invalid argument name `_`
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let _ = format!("{a:_}", a = "", _ = 0);
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//~^ ERROR invalid format string: invalid argument name `_`
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let _ = format!("{a:._$}", a = "", _ = 0);
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//~^ ERROR invalid format string: invalid argument name `_`
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let _ = format!("{");
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//~^ ERROR invalid format string: expected `'}'` but string was terminated
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let _ = format!("}");
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//~^ ERROR invalid format string: unmatched `}` found
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let _ = format!("{\\}");
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//~^ ERROR invalid format string: expected `'}'`, found `'\\'`
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let _ = format!("\n\n\n{\n\n\n");
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//~^ ERROR invalid format string
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let _ = format!(r###"
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{"###);
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//~^ ERROR invalid format string
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let _ = format!(r###"
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{
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"###);
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//~^ ERROR invalid format string
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let _ = format!(r###"
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}
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"###);
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//~^^^ ERROR invalid format string
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let _ = format!(r###"
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}
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"###);
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//~^^^ ERROR invalid format string: unmatched `}` found
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println!("{} {} {}", 1, 2);
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//~^ ERROR 3 positional arguments in format string, but there are 2 arguments
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}
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