Am 25.11.2024 um 17:26 schrieb Edgar Fuß: > Why does C's sizeof operator need parentheses when applied to a type? > > I suspect some ambiguity without the parentheses, but I fail do make up one.
The expression 'sizeof int * + 1' has two different interpretations: sizeof(int) * (+1) sizeof(int *) + 1 I found this out by running: bison -o /dev/null -v --report-file=before usr.bin/xlint/lint1/cgram.y Then I removed the parentheses from the rule 'T_SIZEOF T_LPAREN type_name T_RPAREN' and ran Bison again. There were 23 new conflicts. 21 of these were due to the keywords '_Alignas', '__packed' and '__attribute__', and these are ambiguous in many other places of the lint grammar, so I treated them as unsuspicious. Two of the newly added conflicts were about the T_ASTERISK '*' token. These gave me enough of a hint to come up with the above expression. Roland
