Date: Wed, 18 May 2011 08:32:54 -0400 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: musl 0.7.10 released On Wed, May 18, 2011 at 01:49:47PM +0200, Szabolcs Nagy wrote: > nice > > i see compiler workaround Yes. Fortunately it's not so ugly and it might even make the code more readable to people not familiat with the intricacies of the C preprocessor. > - pcc preprocessor bug with recursive macro expansion > in WHATSNEW > > have you reported the issue to the pcc developers? No. I was planning to but haven't gotten around to it. If you or someone else would be willing to handle it I'd appreciate it. > or can you show me an example where pcc is incorrect? See src/internal/syscall.h I haven't tried reproducing it with a simpler test case, but the basic issue is that the preprocessor does not suppress recursive macro expansion. The __syscall_cp() macro expands to __syscall_cpN (where N=0..6 depending on the number of arguments), which is another macro which expands to __syscall_cp(...). Per the C standard (since original ANSI C), since this instance of __syscall_cp was generated from expanding the __syscall_cp macro earlier, it's not subject to being expanded as a macro again, but pcc tries to expand it anyway and gets in an infinite loop. Rich
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