[E0753] Use of inner doc comment in invalid context

[MahadMuhammad]

Use of inner doc comment in invalid context - E0753

---

Code Tested:

• gcc/testsuite/rust/compile/bad_inner_doc.rs

// ErrorCode - E0753
pub fn main ()
{
  //! inner doc allowed
  let _x = 42;
  // { dg-error "expected outer doc comment, inner doc" "" { target *-*-* } .+1 }
  //! inner doc disallowed
  mod module
  {
    /*! inner doc allowed */
    /// outer doc allowed
    // { dg-error "expected outer doc comment, inner doc" "" { target *-*-* } .+1 }
    /*! but inner doc not here */
    mod x { }
  }
}

Output:

/home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/bad_inner_doc.rs:6:3: error: expected outer doc comment, inner doc ('//!' or '/*!') only allowed at start of item and before any outer attribute or doc ('#[', '///' or '/**') [E0753]
/home/mahad/Desktop/mahad/gccrs/gcc/testsuite/rust/compile/bad_inner_doc.rs:12:5: error: expected outer doc comment, inner doc ('//!' or '/*!') only allowed at start of item and before any outer attribute or doc ('#[', '///' or '/**') [E0753]
compiler exited with status 1
PASS: rust/compile/bad_inner_doc.rs  at line 5 (test for errors, line 6)
PASS: rust/compile/bad_inner_doc.rs  at line 11 (test for errors, line 12)
PASS: rust/compile/bad_inner_doc.rs (test for excess errors)

---

gcc/rust/ChangeLog:

* parse/rust-parse-impl.h (Parser::parse_outer_attribute): Added errorcode & updated error function.

gcc/testsuite/ChangeLog:

* rust/compile/bad_inner_doc.rs: 

[philberty]

LGTM