------- Comment #9 from ilatypov at infradead dot org 2010-03-12 03:49 ------- (In reply to comment #7) > I am reopening the bug cause I still don't have a clue why "pointer to array > of > ints" typed expression is assignment incompatible with a "pointer to array of > const ints" typed lvalue. Especially when "pointer to int" typed expression IS > assignment compatible with "pointer to const int" typed lvalue. This is what > is > this bug all about.
Comment #9 to bug 33076 showed me a link explaining how constness of a multiply referenced value cannot be promised, and, therefore, C propagates the compile -time constness requirement up the assignment chain in cases where the level of pointer indirection is greater than 1. http://c-faq.com/ansi/constmismatch.html I came up with a similar example for the "array of const ints". It shows that the const promise might have been violated inside the function if multiply-indirected lvalue constness was relaxed. typedef const int carr_t[8]; typedef int arr_t[8]; void foo(carr_t *carrp) { arr_t *hacker; carr_t **holder = &hacker; // a warning (*holder) = carrp; // "hacker = carrp" in disguise, but both sides are (carr_t *) (*hacker)[ 0 ] = 9; // no warning } void bar(void) { arr_t arr = { 1, 2, 3, 4, 5, 6, 7, 8 }; foo(arr); // a warning } -- ilatypov at infradead dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ilatypov at infradead dot | |org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16602
