On Wed, Feb 04 2015, Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx> wrote: > On Tue, Feb 03, 2015 at 11:38:02PM +0100, Rasmus Villemoes wrote: >> >> Thanks, but there's still something wrong. Using your show-data feature >> on this: >> >> === >> #define BACKSLASH "\\" >> #define LETTER_t "t" >> >> static const char s1[] = BACKSLASH; >> /* static const char s2[] = BACKSLASH; */ >> static const char s3[] = BACKSLASH LETTER_t; >> static const char s4[] = "a" BACKSLASH LETTER_t "b"; >> === >> >> I get >> >> symbol s1: >> char static const [toplevel] s1[0] >> bit_size = 16 >> val = "\\" >> symbol s3: >> char static const [toplevel] s3[0] >> bit_size = 24 >> val = "\0t" >> symbol s4: >> char static const [toplevel] s4[0] >> bit_size = 40 >> val = "a\0tb" >> >> Now if I do the same with s2 not commented out, I get >> >> >> symbol s1: >> char static const [toplevel] s1[0] >> bit_size = 16 >> val = "\0" >> symbol s2: >> char static const [toplevel] s2[0] >> bit_size = 16 >> val = "\0" >> symbol s3: >> char static const [toplevel] s3[0] >> bit_size = 24 >> val = "\0t" >> symbol s4: >> char static const [toplevel] s4[0] >> bit_size = 40 >> val = "a\0tb" >> >> So the expansion of BACKSLASH changes depending on how often it is >> expanded... >> >> The LETTER_t thing above is because I thought I had somehow provoked a >> double expansion, making BACKSLASH LETTER_t (or some variant) expand to >> a single-character string containing just a tab. But I can't seem to >> reproduce that particular behaviour, so maybe I'm imagining >> stuff. Anyway, the above is certainly real. >> >> Thanks, >> Rasmus >> -- > Yes, I see. > > Now thinking about it, it's obvious that the string buffer can't be reused at all > if there is any kind of expansion done on it, the adjacent strings concatenation > make just the thing worse but are not the cause of it. > That was also my conclusion from looking at the code, but I was unable to do anything about it. And I wasn't hallucinating, I was just overcomplicating things: #define NOT_TAB "\\t" static const char s1[] = NOT_TAB; static const char s2[] = NOT_TAB; indeed fails. Thanks, Rasmus -- To unsubscribe from this list: send the line "unsubscribe linux-sparse" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
