https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87614
Bug ID: 87614
Summary: User related warnings are hidden in system headers
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: antoshkka at gmail dot com
Target Milestone: ---
Consider the following example:
#include <vector>
int main() {
std::vector<unsigned short> a;
a.emplace_back(70000);
}
No warning produced with "--std=c++17 -Wall -Wextra -Werror -pedantic
-Wold-style-cast -Wconversion -Wsign-conversion -Wunreachable-code
-Wno-missing-braces"
However there is an essential warning in new_allocator.h
include/c++/9.0.0/ext/new_allocator.h:139:4: error: conversion from 'long int'
to 'short unsigned int' may change value [-Werror=conversion]
The warning is also visible if we replace `emplace_back` with `push_back`.
The solution would be to enable warnings for all the places where user provided
data types are constructed or any other functions of the user provided types
are called.
