https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106247
Bug ID: 106247
Summary: GCC12 warning in Eigen: array subscript is partly
outside array bounds
Product: gcc
Version: 12.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fchelnokov at gmail dot com
Target Milestone: ---
If one compiles the following program using Eigen 3.4.0:
#include <Eigen/Dense>
int main(){
Eigen::Array<double, 2, 2> a;
a.setRandom();
Eigen::Array<double, 3, 2> b;
b.col(0).tail(2) = a.col(1);
}
in GCC12 with command-line options: -std=c++20 -Wall -Wextra -pedantic-errors
-O2 -march=haswell
then a large error occurs ending with
/opt/compiler-explorer/gcc-12.1.0/lib/gcc/x86_64-linux-gnu/12.1.0/include/avxintrin.h:893:24:
warning: array subscript '__m256d_u[0]' is partly outside array bounds of
'Eigen::Array<double, 2, 2> [1]' [-Warray-bounds]
893 | return *(__m256d_u *)__P;
| ^~~
Similar errors occur with other -march options or other code using Eigen
library.
Everything is fine in GCC 11 or other compilers. Online demo:
https://gcc.godbolt.org/z/hT348GYo9
Is it Eigen or GCC bug? Related discussion:
https://stackoverflow.com/q/72871100/7325599
