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Re: Fix crash with -fdump-ada-spec

On Wed, 21 Aug 2019, Eric Botcazou wrote:

> This fixes a crash of the C compiler when -fdump-ada-spec is passed for:
> extern void (*signal (int __sig, void (*__handler)(int)))(int);
> It appears that the C parser is somewhat confused by this declaration and 
> builds a FUNCTION_DECL whose type has got 2 arguments (TYPE_ARG_TYPES list) 
> but which itself has got only 1 argument (DECL_ARGUMENTS list) corresponding 
> to the anonymous (int) at the end.  The C++ parser doesn't have the issue.
> Joseph, is that a known issue of the C parser?

The problem is that the logic in c_parser_declaration_or_fndef for setting 
DECL_ARGUMENTS (not previously meaningful in non-definition declarations 
at all), as introduced by

r253411 | dmalcolm | 2017-10-04 14:10:59 +0000 (Wed, 04 Oct 2017) | 85 lines

C: underline parameters in mismatching function calls

(and subsequently changed by r268574, but that change isn't relevant here) 
is incorrect.  Rather than checking if the outermost declarator is 
cdk_function and using its parameters if so, it's necessary to check if 
the *innermost declarator that isn't cdk_id or cdk_attrs* is cdk_function 
and use its parameters if so, as that's what actually determines if the 
declarator for the entity being declared has the form of a function 
declarator (see how grokdeclarator determines funcdef_syntax).  In your 
example, the outermost declarator is the one for the target type of the 
pointer that is the return type.

Joseph S. Myers

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