https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83873
--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Joseph Myers <js...@gcc.gnu.org>: https://gcc.gnu.org/g:8f51cf38bb9628546effe66c070188d10f80b5ca commit r12-580-g8f51cf38bb9628546effe66c070188d10f80b5ca Author: Joseph Myers <jos...@codesourcery.com> Date: Thu May 6 23:20:35 2021 +0000 preprocessor: Fix pp-number lexing of digit separators [PR83873, PR97604] When the preprocessor lexes preprocessing numbers in lex_number, it accepts digit separators in more cases than actually permitted in pp-numbers by the standard syntax. One thing this accepts is adjacent digit separators; there is some code to reject those later, but as noted in bug 83873 it fails to cover the case of adjacent digit separators within a floating-point exponent. Accepting adjacent digit separators only results in a missing diagnostic, not in valid code being rejected or being accepted with incorrect semantics, because the correct lexing in such a case would have '' start the following preprocessing tokens, and no valid preprocessing token starts '' while ' isn't valid on its own as a preprocessing token either. So this patch fixes that case by moving the error for adjacent digit separators to lex_number (allowing a more specific diagnostic than if '' were excluded from the pp-number completely). Other cases inappropriately accepted involve digit separators before '.', 'e+', 'e-', 'p+' or 'p-' (or corresponding uppercase variants). In those cases, as shown by the test digit-sep-pp-number.C added, this can result in valid code being wrongly rejected as a result of too many characters being included in the pp-number. So this case is fixed by terminating the pp-number at the correct character according to the standard. That test also covers the case where a digit separator was followed by an identifier-nondigit that is not a nondigit (e.g. a UCN); that case was already handled correctly. Bootstrapped with no regressions for x86_64-pc-linux-gnu. libcpp/ PR c++/83873 PR preprocessor/97604 * lex.c (lex_number): Reject adjacent digit separators here. Do not allow digit separators before '.' or an exponent with sign. * expr.c (cpp_classify_number): Do not check for adjacent digit separators here. gcc/testsuite/ PR c++/83873 PR preprocessor/97604 * g++.dg/cpp1y/digit-sep-neg-2.C, g++.dg/cpp1y/digit-sep-pp-number.C: New tests. * g++.dg/cpp1y/digit-sep-line-neg.C, g++.dg/cpp1y/digit-sep-neg.C: Adjust expected messages.
