On Wed, 2019-01-23 at 20:09 +0100, Michal Sudolsky wrote: > I am tempted to note that -1 is stored in 8-bit integer in exactly > same way as 0xFF.
Hi, I used the code below with gcc 8.1.1 with this result (the result will make sense when the code is read): [0] is -1; same:0/1/0 as signed:-1/255 as unsigned:4294967295/255 switch match: s:1 u:0 [1] is 0; same:1/1/1 as signed:0/0 as unsigned:0/0 switch match: s:1 u:1 [2] is 1; same:1/1/1 as signed:1/1 as unsigned:1/1 switch match: s:1 u:1 [3] is 255; same:0/0/1 as signed:-1/255 as unsigned:4294967295/255 switch match: s:0 u:1 what it should write is to have the 'same' triple all ones in at least one column, not any of them zeros. You can see that 0xff and -1 are not the same when it comes to comparison, either with a real enum value or with signed and unsigned integers. I believe (according to my experience) that enums are like *signed* integers. Thus one might be careful what replacement type is used and which values will be assigned to it. The change mabri committed doesn't fix anything to upstream, it fixes a thing only to Francesco's private (and modified) checkout. The change also doesn't break anything upstream. Unless, some time later, someone decides to make Unknown -1 or anything like that. Then, hopefully, the compiler will claim something, thus it'll be noticed. Bye, zyx The used code follows. It generates compiler warnings with the switch- es, which is for good when looking for mistakes: ---------------------------------------------------- /* g++ test.cpp -o test && ./test */ #include <stdio.h> typedef enum { enMinusOne = -1, enZero = 0, enOne = 1, enFF = 0xFF } EN; int main (void) { signed char n_int8; unsigned char n_uint8; bool smatch, umatch; int ii; EN ens[4] = { enMinusOne, enZero, enOne, enFF }; for (ii = 0; ii < 4; ii++) { n_int8 = ens[ii]; n_uint8 = ens[ii]; #define test_switch(_val,_res) \ switch (_val) { \ case enMinusOne: _res = ii == 0; break; \ case enZero: _res = ii == 1; break; \ case enOne: _res = ii == 2; break; \ case enFF: _res = ii == 3; break; \ default: _res = false; break; \ } test_switch (n_int8, smatch); test_switch (n_uint8, umatch); #undef test_switch printf ("[%d] is %d; same:%d/%d/%d as signed:%d/%d as unsigned:%u/%u switch match: s:%d u:%d\n", ii, ens[ii], n_int8 == n_uint8, n_int8 == ens[ii], n_uint8 == ens[ii], n_int8, n_uint8, n_int8, n_uint8, smatch, umatch); } return 0; } _______________________________________________ Podofo-users mailing list Podofo-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/podofo-users