Wrapping expr in curly braces changes the operator precedence · Issue #28777 · rust-lang/rust (original) (raw)

This program prints different values depending upon whether the v1 or v2 initializer is surrounded by curly braces:

fn main() { let v1 = { 1 + {2} * {3} }; // 9, indicating a parse of (1 + 2) * 3 let v2 = 1 + {2} * {3} ; // 7, indicating a parse of 1 + (2 * 3) println!("{}", v1); println!("{}", v2); }

I think it should print 7 for both lines. parser-lalr -v accepts this program and consistently parses 1 + (2 * 3) for both lines.

|   |   |   |   |   |   |   (ExprBlock
|   |   |   |   |   |   |   |   (ExprBinary
|   |   |   |   |   |   |   |   |   BiAdd
|   |   |   |   |   |   |   |   |   (ExprLit
|   |   |   |   |   |   |   |   |   |   (LitInteger
|   |   |   |   |   |   |   |   |   |   |   1
|   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   (ExprBinary
|   |   |   |   |   |   |   |   |   |   BiMul
|   |   |   |   |   |   |   |   |   |   (ExprBlock
|   |   |   |   |   |   |   |   |   |   |   (ExprLit
|   |   |   |   |   |   |   |   |   |   |   |   (LitInteger
|   |   |   |   |   |   |   |   |   |   |   |   |   2
|   |   |   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   |   (ExprBlock
|   |   |   |   |   |   |   |   |   |   |   (ExprLit
|   |   |   |   |   |   |   |   |   |   |   |   (LitInteger
|   |   |   |   |   |   |   |   |   |   |   |   |   3
|   |   |   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   |   )
|   |   |   |   |   |   |   )