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fix: Fix panic in format_args expansion #15006

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Merged
merged 1 commit into from
Jun 7, 2023
Merged

fix: Fix panic in format_args expansion #15006

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38 changes: 38 additions & 0 deletions crates/hir-def/src/macro_expansion_tests/builtin_fn_macro.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -207,6 +207,44 @@ fn main() {
);
}

#[test]
fn regression_15002() {
check(
r#"
#[rustc_builtin_macro]
macro_rules! format_args {
($fmt:expr) => ({ /* compiler built-in */ });
($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
}

fn main() {
format_args!(x = 2);
format_args!(x =);
format_args!(x =, x = 2);
format_args!("{}", x =);
format_args!(=, "{}", x =);
format_args!(x = 2, "{}", 5);
}
"#,
expect![[r##"
#[rustc_builtin_macro]
macro_rules! format_args {
($fmt:expr) => ({ /* compiler built-in */ });
($fmt:expr, $($args:tt)*) => ({ /* compiler built-in */ })
}

fn main() {
/* error: no rule matches input tokens */;
/* error: no rule matches input tokens */;
/* error: no rule matches input tokens */;
/* error: no rule matches input tokens */::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::Argument::new(&(), ::core::fmt::Display::fmt), ]);
/* error: no rule matches input tokens */;
::core::fmt::Arguments::new_v1(&["", ], &[::core::fmt::Argument::new(&(5), ::core::fmt::Display::fmt), ]);
}
"##]],
);
}

#[test]
fn test_format_args_expand_with_comma_exprs() {
check(
Expand Down
7 changes: 3 additions & 4 deletions crates/hir-expand/src/builtin_fn_macro.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -262,9 +262,6 @@ fn format_args_expand_general(
let expand_error =
ExpandResult::new(tt::Subtree::empty(), mbe::ExpandError::NoMatchingRule.into());

if args.is_empty() {
return expand_error;
}
let mut key_args = FxHashMap::default();
let mut args = args.into_iter().filter_map(|mut arg| {
// Remove `key =`.
Expand All @@ -281,7 +278,9 @@ fn format_args_expand_general(
Some(arg)
}).collect::<Vec<_>>().into_iter();
// ^^^^^^^ we need this collect, to enforce the side effect of the filter_map closure (building the `key_args`)
let format_subtree = args.next().unwrap();
let Some(format_subtree) = args.next() else {
return expand_error;
};
let format_string = (|| {
let token_tree = format_subtree.token_trees.get(0)?;
match token_tree {
Expand Down