4 ms·

There was a proposal during the C23 process to make "main(int argc, char *argv[argc])" work as one would expect, as well as some similar changes elsewhere, such

by wahern 4y ago

There was a proposal during the C23 process to make "main(int argc, char *argv[argc])" work as one would expect, as well as some similar changes elsewhere, such as with structure members. They went through several revisions but never made the cut, I think partially because they all required at least some minimal backward incompatibility. IMO, if GCC or clang implemented and ran with those proposed changes, they'd probably be accepted for the next C revision, and become popular long before then. This is mostly a matter of time and motivation; corporate funded developer time seems to be mostly focused on half measures; e.g. type attributes, rather than fundamentally improving pointer and array semantics. But if someone put in enough time and effort, including going through the rigmarole of integration into mainline, this could happen.

unnah 4y ago
"main(int argc, char *argv[argc])" should already work with C99, shouldn't it? Or was the proposal to make some of the VLA support mandatory again?
- wahern 4y ago
  The syntax is accepted (almost as a fluke), but doesn't work the way anyone would expect because any use of argv still decays to a pointer, even with sizeof. That's in contrast to 'char *argv[argc]' declared as an automatic variable where sizeof computes at runtime the proper array size: 'sizeof (char *) * argc'. The proposals would make function VLA syntax work the same as for automatic variables. In theory it could break existing code, but in practice nobody actually uses this in the wild because the semantics are useless and downright confusing. There's also a related proposal to enhance flexible array members in the manner of VLAs, e.g. 'struct foo { size_t n; int arr[n]; }'. IIRC, the latter syntax is accidentally supported by GCC as a side-effect of another extension, yet GCC wouldn't have minded breaking it even though there's more production code at risk than with the function argument change.

by wahern 4y ago

unnah 4y ago

"main(int argc, char *argv[argc])" should already work with C99, shouldn't it? Or was the proposal to make some of the VLA support mandatory again?

wahern 4y ago
The syntax is accepted (almost as a fluke), but doesn't work the way anyone would expect because any use of argv still decays to a pointer, even with sizeof. That's in contrast to 'char *argv[argc]' declared as an automatic variable where sizeof computes at runtime the proper array size: 'sizeof (char *) * argc'. The proposals would make function VLA syntax work the same as for automatic variables. In theory it could break existing code, but in practice nobody actually uses this in the wild because the semantics are useless and downright confusing. There's also a related proposal to enhance flexible array members in the manner of VLAs, e.g. 'struct foo { size_t n; int arr[n]; }'. IIRC, the latter syntax is accidentally supported by GCC as a side-effect of another extension, yet GCC wouldn't have minded breaking it even though there's more production code at risk than with the function argument change.