https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123127
Bug ID: 123127
Summary: -Wsign-conversion should consider control-flow sentive
range and only warn if problematic numbers are
possible
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: redbeard0531 at gmail dot com
Target Milestone: ---
The following code is perfectly fine, but currently generates a bogus warning:
int f(unsigned);
int test(int i) {
if (i < 0)
return 0;
return f(i);
}
<source>:7:14: warning: conversion to 'unsigned int' from 'int' may change the
sign of the result [-Wsign-conversion]
7 | return f(i);
| ^
`i` can never be negative at that point (and I'm pretty sure other warnings
know that), so there shouldn't be a warning when it gets converted to unsigned.
https://godbolt.org/z/6KzM1K36f
I have also filed a matching bug with clang:
https://github.com/llvm/llvm-project/issues/172279
