https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70769
Bug ID: 70769
Summary: function definition wrongfully allowed inside comma
separated member declaration list
Product: gcc
Version: 5.2.0
Status: UNCONFIRMED
Severity: trivial
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: fourmisain+gcc at gmail dot com
Target Milestone: ---
This code should not compile while it does:
class C {
int n, f(int) {
return 42;
}
};
To break it down (using C++14 standard draft n4140), the only
member-declaration (ยง9.2) which declares multiple members at once is of the
form
attribute-specifier-seq(opt) decl-specifier-seq(opt)
member-declarator-list(opt);
Note that in the above code, the required semicolon at the end is missing, so
this is already in violation of the standard, but the code still compiles
without even a warning (using -std=c++14 -Wall -pedantic) if you add that
missing semicolon.
So continuing the argument, "int n, f(int) {return 42;}" would have to be a
member-declarator-list, so "f(int){return 42;}" would have to be a
member-declarator and since it does not contain a colon it is one of the two:
declarator virt-specifier-seq(opt) pure-specifier(opt)
declarator brace-or-equal-initializer(opt)
Since "{return 42;}" is not a valid brace-or-equal-initializer, "f(int){return
42;}" has to be a declarator.
Afaik, this is not true and it also conflicts with the following:
If it were a declarator, you would be allowed to use it inside a
init-declarator-list, therefore the following code would have to compile:
int n, f(int) {
return 42;
}
But it (rightfully) does not:
"error: a function-definition is not allowed here before '{' token"
So this error message needs to be applied to the above class case.
--------
I was made aware that the above "hack" is often used on CodeFights to save
precious characters. They seems to wrap code into a class and compile it with
g++ 5.0.
