libcpp: Fix up #__VA_OPT__ handling [PR103415] stringify_arg uses pfile->u_buff to create the string literal. Unfortunately, paste_tokens -> _cpp_lex_direct -> lex_number -> _cpp_unaligned_alloc can in some cases use pfile->u_buff too, which results in losing everything prepared for the string literal until the token pasting. The following patch fixes that by not calling paste_token during the construction of the string literal, but doing that before. All the tokens we are processing have been pushed into a token buffer using tokens_buff_add_token so it is fine if we paste some of them in that buffer (successful pasting creates a new token in that buffer), move following tokens if any to make it contiguous, pop (throw away) the extra tokens at the end and then do stringify_arg. Also, paste_tokens now copies over PREV_WHITE and PREV_FALLTHROUGH flags from the original lhs token to the replacement token. Copying that way the PREV_WHITE flag is needed for the #__VA_OPT__ handling and copying over PREV_FALLTHROUGH fixes the new Wimplicit-fallthrough-38.c test. 2021-12-01 Jakub Jelinek PR preprocessor/103415 libcpp/ * macro.c (stringify_arg): Remove va_opt argument and va_opt handling. (paste_tokens): On successful paste or in PREV_WHITE and PREV_FALLTHROUGH flags from the *plhs token to the new token. (replace_args): Adjust stringify_arg callers. For #__VA_OPT__, perform token pasting in a separate loop before stringify_arg call. gcc/testsuite/ * c-c++-common/cpp/va-opt-8.c: New test. * c-c++-common/Wimplicit-fallthrough-38.c: New test. --- libcpp/macro.c.jj +++ libcpp/macro.c @@ -295,7 +295,7 @@ static cpp_context *next_context (cpp_re static const cpp_token *padding_token (cpp_reader *, const cpp_token *); static const cpp_token *new_string_token (cpp_reader *, uchar *, unsigned int); static const cpp_token *stringify_arg (cpp_reader *, const cpp_token **, - unsigned int, bool); + unsigned int); static void paste_all_tokens (cpp_reader *, const cpp_token *); static bool paste_tokens (cpp_reader *, location_t, const cpp_token **, const cpp_token *); @@ -826,8 +826,7 @@ cpp_quote_string (uchar *dest, const uch /* Convert a token sequence FIRST to FIRST+COUNT-1 to a single string token according to the rules of the ISO C #-operator. */ static const cpp_token * -stringify_arg (cpp_reader *pfile, const cpp_token **first, unsigned int count, - bool va_opt) +stringify_arg (cpp_reader *pfile, const cpp_token **first, unsigned int count) { unsigned char *dest; unsigned int i, escape_it, backslash_count = 0; @@ -844,24 +843,6 @@ stringify_arg (cpp_reader *pfile, const { const cpp_token *token = first[i]; - if (va_opt && (token->flags & PASTE_LEFT)) - { - location_t virt_loc = pfile->invocation_location; - const cpp_token *rhs; - do - { - if (i == count) - abort (); - rhs = first[++i]; - if (!paste_tokens (pfile, virt_loc, &token, rhs)) - { - --i; - break; - } - } - while (rhs->flags & PASTE_LEFT); - } - if (token->type == CPP_PADDING) { if (source == NULL @@ -995,6 +976,7 @@ paste_tokens (cpp_reader *pfile, locatio return false; } + lhs->flags |= (*plhs)->flags & (PREV_WHITE | PREV_FALLTHROUGH); *plhs = lhs; _cpp_pop_buffer (pfile); return true; @@ -1937,8 +1919,7 @@ replace_args (cpp_reader *pfile, cpp_has if (src->flags & STRINGIFY_ARG) { if (!arg->stringified) - arg->stringified = stringify_arg (pfile, arg->first, arg->count, - false); + arg->stringified = stringify_arg (pfile, arg->first, arg->count); } else if ((src->flags & PASTE_LEFT) || (src != macro->exp.tokens && (src[-1].flags & PASTE_LEFT))) @@ -2065,11 +2046,46 @@ replace_args (cpp_reader *pfile, cpp_has { unsigned int count = start ? paste_flag - start : tokens_buff_count (buff); - const cpp_token *t - = stringify_arg (pfile, - start ? start + 1 - : (const cpp_token **) (buff->base), - count, true); + const cpp_token **first + = start ? start + 1 + : (const cpp_token **) (buff->base); + unsigned int i, j; + + /* Paste any tokens that need to be pasted before calling + stringify_arg, because stringify_arg uses pfile->u_buff + which paste_tokens can use as well. */ + for (i = 0, j = 0; i < count; i++, j++) + { + const cpp_token *token = first[i]; + + if (token->flags & PASTE_LEFT) + { + location_t virt_loc = pfile->invocation_location; + const cpp_token *rhs; + do + { + if (i == count) + abort (); + rhs = first[++i]; + if (!paste_tokens (pfile, virt_loc, &token, rhs)) + { + --i; + break; + } + } + while (rhs->flags & PASTE_LEFT); + } + + first[j] = token; + } + if (j != i) + { + while (i-- != j) + tokens_buff_remove_last_token (buff); + count = j; + } + + const cpp_token *t = stringify_arg (pfile, first, count); while (count--) tokens_buff_remove_last_token (buff); if (src->flags & PASTE_LEFT) --- gcc/testsuite/c-c++-common/cpp/va-opt-8.c.jj +++ gcc/testsuite/c-c++-common/cpp/va-opt-8.c @@ -0,0 +1,18 @@ +/* PR preprocessor/103415 */ +/* { dg-do run } */ +/* { dg-options "-std=gnu99" { target c } } */ +/* { dg-options "-std=c++20" { target c++ } } */ + +#define n(x, ...) = #__VA_OPT__(x##3) +#define o(x, ...) #__VA_OPT__(x##__VA_ARGS__##9) +const char *c n(1 2, 4); +const char *d = o(5 6, 7 8); + +int +main () +{ + if (__builtin_strcmp (c, "1 23") + || __builtin_strcmp (d, "5 67 89")) + __builtin_abort (); + return 0; +} --- gcc/testsuite/c-c++-common/Wimplicit-fallthrough-38.c.jj +++ gcc/testsuite/c-c++-common/Wimplicit-fallthrough-38.c @@ -0,0 +1,24 @@ +/* { dg-do compile } */ +/* { dg-options "-Wimplicit-fallthrough=3" } */ + +#define FOO \ +int \ +foo (int a) \ +{ \ + switch (a) \ + { \ + case 1: \ + ++a; \ + /* FALLTHRU */ \ + case 2: \ + ++a; \ + /* FALLTHRU */ \ + ca##se 3: \ + ++a; \ + default: \ + break; \ + } \ + return a; \ +} + +FOO