[Bug c++/99689] New: Initialized local variable becomes uninitialized after use
soren.soe at gonsoe dot com
gcc-bugzilla@gcc.gnu.org
Sat Mar 20 20:11:11 GMT 2021
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99689
Bug ID: 99689
Summary: Initialized local variable becomes uninitialized after
use
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: soren.soe at gonsoe dot com
Target Milestone: ---
Created attachment 50439
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50439&action=edit
preprocessed file (*.i*) that triggers the bug
% g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/aarch64-linux-gnu/9/lto-wrapper
Target: aarch64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu
9.3.0-17ubuntu1~20.04' --with-bugurl=file:///usr/share/doc/gcc-9/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,gm2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-9
--program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new
--enable-gnu-unique-object --disable-libquadmath --disable-libquadmath-support
--enable-plugin --enable-default-pie --with-system-zlib
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release
--build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu
Thread model: posix
gcc version 9.3.0 (Ubuntu 9.3.0-17ubuntu1~20.04)
% cat bug.cpp
#include <cassert>
#include <string>
#include <utility>
#include <vector>
using vec = std::vector<std::pair<std::string, std::string>>;
void
bad()
{
vec v;
v.emplace_back("abc", "def");
v.emplace_back("abc", "def");
v.emplace_back("abc", "def");
v.emplace_back("abc", "def");
v.emplace_back("abc", "def");
unsigned int m = 0;
for (auto& p : v)
m = std::max<unsigned int>(m, p.first.length());
assert(m == 3);
}
int main()
{
bad();
return 0;
}
% g++ -Wall -Wextra -O3 -std=c++14 bug.cpp
% ./a.out
a.out: bug.cpp:79: void bad(): Assertion `m == 3' failed.
Aborted (core dumped)
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