MSVC `type cast`: cannot convert from `Type` to `Type`-CodePudding

I'm trying to compile this:

typedef struct Type {
    int value;
} Type;


Type foobar(Type value) { return (Type)value; }

In MSVC2017, this throws the following error:

C2440: 'type cast': cannot convert from 'Type' to 'Type'

This doesn't seem to happen if the filename ends in .cpp as opposed to .c. This also doesn't seem to happen with gcc. Why does this happen?

CodePudding user response：

(Type)value violates the constraint in C 2018 6.5.4 2, which covers the cast operator:

Unless the type name specifies a void type, the type name shall specify atomic, qualified, or unqualified scalar type,…

A scalar type is an arithmetic or pointer type, per C 2018 6.2.5 21:

Arithmetic types and pointer types are collectively called scalar types. Array and structure types are collectively called aggregate types.

C has different rules and GCC, in its default mode, does not conform to the C standard in this respect.

There is no need for a cast here; in the return statement, value refers to the value parameter of the function, which has type Type. So return value; would suffice.