https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87994
--- Comment #8 from Dominique d'Humieres <dominiq at lps dot ens.fr> --- I have instrumented gfortran with the patch in comment 5 and all the tests fail as with pr87881: ================================================================= ==67715==ERROR: AddressSanitizer: heap-use-after-free on address 0x6170000045d8 at pc 0x0001001565a9 bp 0x7ffeefbfdd30 sp 0x7ffeefbfdd28 READ of size 8 at 0x6170000045d8 thread T0 #0 0x1001565a8 in simplify_ref_chain(gfc_ref*, int, gfc_expr**) expr.c:1943 #1 0x10015438e in gfc_simplify_expr(gfc_expr*, int) expr.c:2164 #2 0x100369eaf in gfc_match_varspec(gfc_expr*, int, bool, bool) primary.c:2287 #3 0x1003798ba in gfc_match_rvalue(gfc_expr**) primary.c:3670 #4 0x1000c2f63 in match_data_constant(gfc_expr**) decl.c:379 #5 0x1000c4291 in top_val_list(gfc_data*) decl.c:478 #6 0x1000c4905 in gfc_match_data() decl.c:624 #7 0x10032fbc7 in match_word(char const*, match (*)(), locus*) parse.c:65 #8 0x10033d154 in decode_statement() parse.c:468 #9 0x10033ee0d in next_free() parse.c:1234 #10 0x10033f7d2 in next_statement() parse.c:1466 #11 0x100345d67 in parse_spec(gfc_statement) parse.c:3858 #12 0x10034c892 in parse_progunit(gfc_statement) parse.c:5671 #13 0x10034ec10 in gfc_parse_file() parse.c:6211 #14 0x100525304 in gfc_be_parse_file() f95-lang.c:204 #15 0x1062941c8 in compile_file() toplev.c:455 #16 0x10629f87c in do_compile() toplev.c:2172 #17 0x109388807 in toplev::main(int, char**) toplev.c:2307 #18 0x1097eaf4c in main main.c:39 #19 0x7fff703f908c in start (libdyld.dylib:x86_64+0x1708c) 0x6170000045d8 is located 728 bytes inside of 736-byte region [0x617000004300,0x6170000045e0) freed by thread T0 here: #0 0x15948a8e0 in wrap_free.part.0 sanitizer_malloc_mac.inc:121 #1 0x10012e8e5 in gfc_free_ref_list(gfc_ref*) expr.c:599 #2 0x10012efdd in free_expr0(gfc_expr*) expr.c:505 #3 0x10012f3be in gfc_replace_expr(gfc_expr*, gfc_expr*) expr.c:616 #4 0x1001563b7 in simplify_ref_chain(gfc_ref*, int, gfc_expr**) expr.c:1970 #5 0x10015438e in gfc_simplify_expr(gfc_expr*, int) expr.c:2164 #6 0x100369eaf in gfc_match_varspec(gfc_expr*, int, bool, bool) primary.c:2287 #7 0x1003798ba in gfc_match_rvalue(gfc_expr**) primary.c:3670 #8 0x1000c2f63 in match_data_constant(gfc_expr**) decl.c:379 #9 0x1000c4291 in top_val_list(gfc_data*) decl.c:478 #10 0x1000c4905 in gfc_match_data() decl.c:624 #11 0x10032fbc7 in match_word(char const*, match (*)(), locus*) parse.c:65 #12 0x10033d154 in decode_statement() parse.c:468 #13 0x10033ee0d in next_free() parse.c:1234 #14 0x10033f7d2 in next_statement() parse.c:1466 #15 0x100345d67 in parse_spec(gfc_statement) parse.c:3858 #16 0x10034c892 in parse_progunit(gfc_statement) parse.c:5671 #17 0x10034ec10 in gfc_parse_file() parse.c:6211 #18 0x100525304 in gfc_be_parse_file() f95-lang.c:204 #19 0x1062941c8 in compile_file() toplev.c:455 #20 0x10629f87c in do_compile() toplev.c:2172 #21 0x109388807 in toplev::main(int, char**) toplev.c:2307 #22 0x1097eaf4c in main main.c:39 #23 0x7fff703f908c in start (libdyld.dylib:x86_64+0x1708c) previously allocated by thread T0 here: #0 0x159489db3 in wrap_calloc sanitizer_malloc_mac.inc:132 #1 0x1088a10de in xcalloc xmalloc.c:162 #2 0x10035b5ae in is_inquiry_ref(char const*, gfc_ref**) primary.c:1964 #3 0x100368721 in gfc_match_varspec(gfc_expr*, int, bool, bool) primary.c:2199 #4 0x1003798ba in gfc_match_rvalue(gfc_expr**) primary.c:3670 #5 0x1000c2f63 in match_data_constant(gfc_expr**) decl.c:379 #6 0x1000c4291 in top_val_list(gfc_data*) decl.c:478 #7 0x1000c4905 in gfc_match_data() decl.c:624 #8 0x10032fbc7 in match_word(char const*, match (*)(), locus*) parse.c:65 #9 0x10033d154 in decode_statement() parse.c:468 #10 0x10033ee0d in next_free() parse.c:1234 #11 0x10033f7d2 in next_statement() parse.c:1466 #12 0x100345d67 in parse_spec(gfc_statement) parse.c:3858 #13 0x10034c892 in parse_progunit(gfc_statement) parse.c:5671 #14 0x10034ec10 in gfc_parse_file() parse.c:6211 #15 0x100525304 in gfc_be_parse_file() f95-lang.c:204 #16 0x1062941c8 in compile_file() toplev.c:455 #17 0x10629f87c in do_compile() toplev.c:2172 #18 0x109388807 in toplev::main(int, char**) toplev.c:2307 #19 0x1097eaf4c in main main.c:39 #20 0x7fff703f908c in start (libdyld.dylib:x86_64+0x1708c) SUMMARY: AddressSanitizer: heap-use-after-free expr.c:1943 in simplify_ref_chain(gfc_ref*, int, gfc_expr**) Shadow bytes around the buggy address: 0x1c2e00000860: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x1c2e00000870: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x1c2e00000880: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x1c2e00000890: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd 0x1c2e000008a0: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd =>0x1c2e000008b0: fd fd fd fd fd fd fd fd fd fd fd[fd]fa fa fa fa 0x1c2e000008c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa 0x1c2e000008d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1c2e000008e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1c2e000008f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 0x1c2e00000900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 Shadow byte legend (one shadow byte represents 8 application bytes): Addressable: 00 Partially addressable: 01 02 03 04 05 06 07 Heap left redzone: fa Freed heap region: fd Stack left redzone: f1 Stack mid redzone: f2 Stack right redzone: f3 Stack after return: f5 Stack use after scope: f8 Global redzone: f9 Global init order: f6 Poisoned by user: f7 Container overflow: fc Array cookie: ac Intra object redzone: bb ASan internal: fe Left alloca redzone: ca Right alloca redzone: cb Shadow gap: cc ==67715==ABORTING f951: internal compiler error: Abort trap: 6