https://gcc.gnu.org/g:6e10ec0cd82b7611b792e80eee2bd1f24b603d00
commit r16-9013-g6e10ec0cd82b7611b792e80eee2bd1f24b603d00 Author: Marek Polacek <[email protected]> Date: Thu May 28 13:43:58 2026 -0400 c++: fix infinite looping with arr[arr] [PR125454] Here r16-3466 moved the canonicalization step that transforms idx[array] to array[idx] to the beginning of cp_build_array_ref. When we have array[array], we'll be swapping till we blow the stack. Previously, we'd give the !INTEGRAL_OR_UNSCOPED_ENUMERATION_TYPE_P error so there was no problem. PR c++/125454 gcc/cp/ChangeLog: * typeck.cc (cp_build_array_ref): Don't recurse for array[array]. gcc/testsuite/ChangeLog: * g++.dg/other/array8.C: New test. Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit a33b41d895f55fd95f8c9f486f6ef23c71a7a1e5) Diff: --- gcc/cp/typeck.cc | 3 ++- gcc/testsuite/g++.dg/other/array8.C | 15 +++++++++++++++ 2 files changed, 17 insertions(+), 1 deletion(-) diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc index dcc35ae28a24..f6b8b26c542c 100644 --- a/gcc/cp/typeck.cc +++ b/gcc/cp/typeck.cc @@ -4162,7 +4162,8 @@ cp_build_array_ref (location_t loc, tree array, tree idx, return error_mark_node; /* 0[array] */ - if (TREE_CODE (TREE_TYPE (idx)) == ARRAY_TYPE) + if (TREE_CODE (TREE_TYPE (idx)) == ARRAY_TYPE + && TREE_CODE (TREE_TYPE (array)) != ARRAY_TYPE) { std::swap (array, idx); diff --git a/gcc/testsuite/g++.dg/other/array8.C b/gcc/testsuite/g++.dg/other/array8.C new file mode 100644 index 000000000000..d238e3ba5898 --- /dev/null +++ b/gcc/testsuite/g++.dg/other/array8.C @@ -0,0 +1,15 @@ +// PR c++/125454 +// { dg-do compile { target c++11 } } + +template <typename T> +void +foo() +{ + T a = a[a]; // { dg-error "array subscript is not an integer" } +} + +void +bar () +{ + foo<int[]>; +}
