Hi. I've been tinkering again with the dist I shared before in http://adr.freeshell.org/plan9, basically 9legacy + Miller's 9pi + 9front's libseq. Importing ori's git9 I noticed that the compiler was truncating a constant without the correspondent suffix.
According to C99, the type of a constant should be the first in which its value can be represented following this table: Suffix Decimal 0 or 0x ---------------------------------------------------------- none int int long int unsigned int long long int long int unsigned long int unsigned long long int ---------------------------------------------------------- u|U unsigned int unsigned int unsigned long int unsigned long int unsigned long long int unsigned long long int ---------------------------------------------------------- l|L long int long int long long int unsigned long int long long int unsigned long long int ---------------------------------------------------------- u|U & l|L unsigned long int unsigned long int unsigned long long int unsigned long long int ---------------------------------------------------------- ll|LL long long int long long int unsigned long long int ---------------------------------------------------------- u|U & ll|LL unsigned long long int ---------------------------------------------------------- Which follows the K&R description at "A.2.5.1 Integer Constants", just adding LL. Now, in plan9 constants are of type int if there is no suffix, or of the one specified by the suffix. The only change made is from a signed type to an unsigned one if it is necessary to fit the constant's value. The rest is truncated: /sys/src/cmd/cc/lex.c: [...] vv = yylval.vval; if(c1 & Numvlong) { if((c1 & Numuns) || convvtox(vv, TVLONG) < 0) { c = LUVLCONST; t = TUVLONG; goto nret; } c = LVLCONST; t = TVLONG; goto nret; } if(c1 & Numlong) { if((c1 & Numuns) || convvtox(vv, TLONG) < 0) { c = LULCONST; t = TULONG; goto nret; } c = LLCONST; t = TLONG; goto nret; } if((c1 & Numuns) || convvtox(vv, TINT) < 0) { c = LUCONST; t = TUINT; goto nret; } c = LCONST; t = TINT; goto nret; nret: yylval.vval = convvtox(vv, t); if(yylval.vval != vv){ nearln = lineno; warn(Z, "truncated constant: %T %s", types[t], symb); } return c; [...] 9front introduces some widening: [...] vv = yylval.vval; /* * c99 is silly: decimal constants stay signed, * hex and octal go unsigned before widening. */ w = 32; if((c1 & (Numdec|Numuns)) == Numdec) w = 31; if(c1 & Numvlong || (c1 & Numlong) == 0 && (uvlong)vv >= 1ULL<<w){ if((c1&(Numdec|Numvlong)) == Numdec && vv < 1ULL<<32) warn(Z, "int constant widened to vlong: %s", symb); if((c1 & Numuns) || convvtox(vv, TVLONG) < 0) { c = LUVLCONST; t = TUVLONG; goto nret; } c = LVLCONST; t = TVLONG; goto nret; } if(c1 & Numlong) { [...] It doesn't follow c99. Constants with explicit L prefix which doesn't fit in a ulong type will not be promoted to vlong but truncated as ulong. Removing '(c1 & Numlong) == 0' should do the trick, I think, but I don't like the code. The promotion of type from int to vlong only occurs just because all the compilers define int and long with the same width, and because that width is precisely 4 bytes. The rest of the original code is clearly not taking that fact into account which is in my opinion the correct approach. Forcing to specify explicitly the type if a different one from an int is desired is interesting, but the automatic conversion to an unsigned one already brakes the idea, doesn't it?. Some thoughts to help me decide what to do in my dist? Regards, adr. ------------------------------------------ 9fans: 9fans Permalink: https://9fans.topicbox.com/groups/9fans/T22754f10b241991c-Mb38696f1b928920ec2c4d16d Delivery options: https://9fans.topicbox.com/groups/9fans/subscription