Rationale (February, 2021):

This issue was resolved by the resolution of issue 1352.

Additional note, January, 2012:

brace-or-equal-initializers for non-static data members are intended effectively as syntactic sugar for mem-initializers in constructor definitions; the lookup should be the same.

The description of name lookup in the parameter-declaration-clause of member functions in 6.5.3 [basic.lookup.unqual] paragraphs 7-8 is flawed in at least two regards.

First, both paragraphs 7 and 8 apply to the parameter-declaration-clause of a member function definition and give different rules for the lookup. Paragraph 7 applies to names "used in the definition of a class X outside of a member function body...," which includes the parameter-declaration-clause of a member function definition, while paragraph 8 applies to names following the function's declarator-id (see the proposed resolution of issue 41), including the parameter-declaration-clause.

Second, paragraph 8 appears to apply to the type names used in the parameter-declaration-clause of a member function defined inside the class definition. That is, it appears to allow the following code, which was not the intent of the Committee:

    struct S {
        void f(I i) { }
        typedef int I;
    };