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Diffstat (limited to 'tests/ui/lexer/error-stage.rs')
-rw-r--r-- | tests/ui/lexer/error-stage.rs | 80 |
1 files changed, 80 insertions, 0 deletions
diff --git a/tests/ui/lexer/error-stage.rs b/tests/ui/lexer/error-stage.rs new file mode 100644 index 000000000..c8d88f745 --- /dev/null +++ b/tests/ui/lexer/error-stage.rs @@ -0,0 +1,80 @@ +// This test is about the treatment of invalid literals. In particular, some +// literals are only considered invalid if they survive to HIR lowering. +// +// Literals with bad suffixes +// -------------------------- +// Literals consist of a primary part and an optional suffix. +// https://doc.rust-lang.org/reference/tokens.html#suffixes says: +// +// Any kind of literal (string, integer, etc) with any suffix is valid as a +// token, and can be passed to a macro without producing an error. The macro +// itself will decide how to interpret such a token and whether to produce an +// error or not. +// +// ``` +// macro_rules! blackhole { ($tt:tt) => () } +// blackhole!("string"suffix); // OK +// ``` +// +// However, suffixes on literal tokens parsed as Rust code are restricted. +// Any suffixes are rejected on non-numeric literal tokens, and numeric +// literal tokens are accepted only with suffixes from the list below. +// +// Integer: u8, i8, u16, i16, u32, i32, u64, i64, u128, i128, usize, isize +// Floating-point: f32, f64 +// +// This means that something like `"string"any_suffix` is a token accepted by +// the lexer, but rejected later for being an invalid combination of primary +// part and suffix. +// +// `0b10f32` is a similar case. `0b10` is a valid primary part that is a valid +// *integer* literal when no suffix is present. It only causes an error later +// when combined with the `f32` float suffix. +// +// However, `0b10.0f32` is different. It is rejected by the lexer because +// `0b10.0` is not a valid token even on its own. +// +// This difference is unfortunate, but it's baked into the language now. +// +// Too-large integer literals +// -------------------------- +// https://doc.rust-lang.org/reference/tokens.html#integer-literals says that +// literals like `128_i8` and `256_u8` "are too big for their type, but are +// still valid tokens". + +macro_rules! sink { + ($($x:tt;)*) => {()} +} + +// The invalid literals are ignored because the macro consumes them. Except for +// `0b10.0f32` because it's a lexer error. +const _: () = sink! { + "string"any_suffix; // OK + 10u123; // OK + 10.0f123; // OK + 0b10f32; // OK + 0b10.0f32; //~ ERROR binary float literal is not supported + 999340282366920938463463374607431768211455999; // OK +}; + +// The invalid literals used to cause errors, but this was changed by #102944. +// Except for `0b010.0f32`, because it's a lexer error. +#[cfg(FALSE)] +fn configured_out() { + "string"any_suffix; // OK + 10u123; // OK + 10.0f123; // OK + 0b10f32; // OK + 0b10.0f32; //~ ERROR binary float literal is not supported + 999340282366920938463463374607431768211455999; // OK +} + +// All the invalid literals cause errors. +fn main() { + "string"any_suffix; //~ ERROR suffixes on string literals are invalid + 10u123; //~ ERROR invalid width `123` for integer literal + 10.0f123; //~ ERROR invalid width `123` for float literal + 0b10f32; //~ ERROR binary float literal is not supported + 0b10.0f32; //~ ERROR binary float literal is not supported + 999340282366920938463463374607431768211455999; //~ ERROR integer literal is too large +} |