When reading section 6.7.3.1 of the C standard (quoted below) about the *restrict *type qualifier, the first section talks about *ordinary identifiers*. These are defined in section 6.2.3, and exclude members of structures. Let D be a declaration of an ordinary identifier that provides a means of > designating an object P as a restrict-qualified pointer to type T. I would assume that this means that in the code excerpt below the function *h* cannot be optimized by substituting the load of *b.p *for *10*, as the standard does not specify what it means for a struct member to be restrict qualified. However, the code is still optimized by gcc (but not Clang), as can be seen here: https://godbolt.org/z/hEnKKoaae struct bar { int* restrict p; int* restrict q; }; int h(struct bar b) { *b.p = 10; *b.q = 11; return *b.p; } Was this a deliberate choice, or does it simply follow from how restrict is supported in gcc (and could this be considered a bug w.r.t. the standard)?