Dear Harald, hi all,
On 12.09.21 20:40, Harald Anlauf via Fortran wrote:
in find_substring_ref we erroneously handled given substring start and end
indices as unsigned integers. However, gives indices could be negative,
which is legal as long as end < start, leading to a string of length zero.
The current behavior could lead to a wrong length as well as an invalid read
from (compiler) memory.
The fix allows to reintroduce code in testcase substr_6.f90 that was
erroneously considered as illegal.
Regtested on x86_64-pc-linux-gnu. OK for mainline?
As this is invalid code, I'd like to backport this fix.
OK to both – thanks for patch and all your recent patch work!
Tobias
Fortran - fix handling of substring start and end indices
gcc/fortran/ChangeLog:
PR fortran/85130
* expr.c (find_substring_ref): Handle given substring start and
end indices as signed integers, not unsigned.
gcc/testsuite/ChangeLog:
PR fortran/85130
* gfortran.dg/substr_6.f90: Revert commit r8-7574, adding again
test that was erroneously considered as illegal.
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