https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103145
Bug ID: 103145 Summary: False positive of -Wstringop-overread on gcc-11 Product: gcc Version: 11.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: tonyfettes at tonyfettes dot com Target Milestone: --- Hi, The following piece of code will trigger -Wstringop-overread $ cat test.c // test.c #include <stdio.h> #define ARRAY_SIZE 4 struct func_in_t { int x; int y; }; struct example_t { int field0; int field1; int field2; int field3; int field4; }; struct example_t func(const struct func_in_t *in, const int array[ARRAY_SIZE]) { struct example_t out = {0}; return out; } int main() { int array[ARRAY_SIZE] = { 0, 0, 0, 0 }; struct func_in_t in = { .x = 0, .y = 0, }; struct example_t col = func(&in, array); (void) col; return 0; } $ gcc -fno-strict-aliasing -fwrapv -Wall test.c -o test test.c: In function ‘main’: test.c:30:26: warning: ‘func’ reading 16 bytes from a region of size 8 [-Wstringop-overread] 30 | struct example_t col = func(&in, array); | ^~~~~~~~~~~~~~~~ test.c:30:26: note: referencing argument 2 of type ‘const int *’ test.c:19:18: note: in a call to function ‘func’ 19 | struct example_t func(const struct func_in_t *in, const int array[ARRAY_SIZE]) { | ^~~~ $ gcc -v Using built-in specs. COLLECT_GCC=gcc COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/11.1.0/lto-wrapper Target: x86_64-pc-linux-gnu Configured with: /build/gcc/src/gcc/configure --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++,d --with-isl --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-install-libiberty --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-libunwind-exceptions --disable-werror gdc_include_dir=/usr/include/dlang/gdc Thread model: posix Supported LTO compression algorithms: zlib zstd gcc version 11.1.0 (GCC) It seems like a duplication of https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101854, but I'm not sure about it since gcc gave different diagnostics (one is overread, the other is overflow), so I decide to submit it anyway.