https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87406
Manuel López-Ibáñez <manu at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |manu at gcc dot gnu.org --- Comment #2 from Manuel López-Ibáñez <manu at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #1) > We do warn about this, but only with -Wconversion which is not in -Wall or > -Wextra > > c.cc:1:24: warning: conversion to ‘char’ from ‘int’ may alter its value > [-Wconversion] > char f(int i) { return i; } This is not the "constant" case. A testcase would be: char foo(void) { return 132; } <source>: In function 'char square()': <source>:3:12: warning: conversion from 'int' to 'char' changes value from '132' to ''\37777777604'' [-Wconversion] return 132; ^~~ I think the constant case should be safe for -Wall. It is a just a matter of adding more specific flags.