https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101982
Bug ID: 101982
Summary: function parameter should not accept auto as
placeholder-type-specifier
Product: gcc
Version: 7.5.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: nickhuang99 at hotmail dot com
Target Milestone: ---
GCC7.5 accepts *auto* as placeholder-type-specifier without error or warning.
Considering following code snippet is legal only with -std=c++20:
void f(auto i){}
GCC8.x and later gives warning which is at least not incorrect. As a contrast,
both clang (https://www.godbolt.org/z/9x6E5xrne) and
MSVC(https://www.godbolt.org/z/3hWPsrcqz) considers it is illegal without
-std=c++20 option which is compliant with spec:
warning: use of ‘auto’ in parameter declaration only available with
‘-fconcepts-ts’
