The presence of preprocessor directives within the arguments of a macro invocation is Undefined Behaviour. Some of these directives, like the conditionals, are harmless. OTOH, the redefinition of a macro during its own expansion is really nasty. However, it can be given a reasonable meaning: * use the initial definition for the macro body * use the new defintion for its arguments, in text order. It's what gcc & clang do. But Sparse can't handle this because during the expansion, a reference to the initial macro's body is not kept. What is used instead is the 'body currently associated with the macro'. Fix this by always using the body associated with the macro at the time of its invocation. Testcase-by: Oleg Nesterov <oleg@xxxxxxxxxx> Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> --- pre-process.c | 4 ++-- validation/preprocessor/expand-redef.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+), 2 deletions(-) create mode 100644 validation/preprocessor/expand-redef.c diff --git a/pre-process.c b/pre-process.c index 2893c3ab65d4..6670fb0cd557 100644 --- a/pre-process.c +++ b/pre-process.c @@ -756,7 +756,7 @@ static int expand(struct token **list, struct symbol *sym) struct token *last; struct token *token = *list; struct ident *expanding = token->ident; - struct token **tail; + struct token **tail, *expansion = sym->expansion; int nargs = sym->arglist ? sym->arglist->count.normal : 0; struct arg args[nargs]; @@ -776,7 +776,7 @@ static int expand(struct token **list, struct symbol *sym) expanding->tainted = 1; last = token->next; - tail = substitute(list, sym->expansion, args); + tail = substitute(list, expansion, args); /* * Note that it won't be eof - at least TOKEN_UNTAINT will be there. * We still can lose the newline flag if the sucker expands to nothing, diff --git a/validation/preprocessor/expand-redef.c b/validation/preprocessor/expand-redef.c new file mode 100644 index 000000000000..4ca13e661fa4 --- /dev/null +++ b/validation/preprocessor/expand-redef.c @@ -0,0 +1,15 @@ +#define f(x) x x +f(1 +#undef f +#define f 2 + f) + +/* + * check-name: expand-redef + * check-command: sparse -E -Wno-directive-within-macro $file + * + * check-output-start + +1 2 1 2 + * check-output-end + */ -- 2.25.1
