https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70693
--- Comment #10 from David Malcolm <dmalcolm at gcc dot gnu.org> --- Author: dmalcolm Date: Thu Aug 16 17:07:15 2018 New Revision: 263595 URL: https://gcc.gnu.org/viewcvs?rev=263595&root=gcc&view=rev Log: -Wmisleading-indentation: fix ICE in get_visual_column (PR c++/70693) PR c++/70693 reports a crash within -Wmisleading-indentation in get_visual_column, reading past the end of a source line. The issue occurs due to a stray carriage return aka '\r' aka ^M, occurring towards the end of line 35 of attachment 38289 - but not at the end itself. This carriage return confuses our line numbering: from that point in the file, the lexer (and thus location_t values) use line numbers that are one larger than those seen by input.c, "cat -n" and emacs. This discrepancy between the lexer's line numbering and input.c's line numbering leads to an out-of-range read in get_visual_column (trying to read column 8, to locate the first non-whitespace on the line containing "break;", but finding the next line, which is only 4 characters long). This patch fixes the ICE by adding a range check to get_visual_column before accessing the input.c line buffer. This is arguably papering over the root cause, but there are presumably other ways of triggering such an out-of-range read by writing to the source file after the lexer but before -Wmisleading-indentation, and we ought to be not ICE in the face of that. gcc/c-family/ChangeLog: PR c++/70693 * c-common.c (selftest::c_family_tests): Call selftest::c_indentation_c_tests. * c-common.h (selftest::c_indentation_c_tests): New decl. * c-indentation.c: Include "selftest.h". (next_tab_stop): Add "tab_width" param, rather than accessing cpp_opts. (get_visual_column): Likewise. Clarify comment. Bulletproof against reading past the end of the line. (get_first_nws_vis_column): Add "tab_width" param. (detect_intervening_unindent): Likewise. (should_warn_for_misleading_indentation): Read tab width from cpp_opts and pass around. (selftest::test_next_tab_stop): New test. (selftest::assert_get_visual_column_succeeds): New function. (ASSERT_GET_VISUAL_COLUMN_SUCCEEDS): New macro. (selftest::assert_get_visual_column_fails): New function. (ASSERT_GET_VISUAL_COLUMN_FAILS): New macro. (selftest::test_get_visual_column): New test. (selftest::c_indentation_c_tests): New function. gcc/testsuite/ChangeLog: PR c++/70693 * c-c++-common/Wmisleading-indentation-pr70693.c: New test. Added: trunk/gcc/testsuite/c-c++-common/Wmisleading-indentation-pr70693.c Modified: trunk/gcc/c-family/ChangeLog trunk/gcc/c-family/c-common.c trunk/gcc/c-family/c-common.h trunk/gcc/c-family/c-indentation.c trunk/gcc/testsuite/ChangeLog
