Explicit specialization in non-namespace scope does not compile in GCC

Solution 1:

This should be a GCC bug. Full specialization should be allowed in any scope, including in class definition.

According to CWG 727, [temp.expl.spec] paragraph 2 was changed from

(emphasis mine)

An explicit specialization shall be declared in a namespace enclosing the specialized template. An explicit specialization whose declarator-id or class-head-name is not qualified shall be declared in the nearest enclosing namespace of the template, or, if the namespace is inline (10.3.1 [namespace.def]), any namespace from its enclosing namespace set. Such a declaration may also be a definition. If the declaration is not a definition, the specialization may be defined later (10.3.1.2 [namespace.memdef]).

to

(emphasis mine)

An explicit specialization may be declared in any scope in which the corresponding primary template may be defined (10.3.1.2 [namespace.memdef], 12.2 [class.mem], 17.6.2 [temp.mem]).

It seems GCC fails to follow this.

EDIT

I have reported the issue as Bug 85282.