https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87406
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- 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; } ^