===================================================================
@@ -5914,15 +5914,30 @@ package body Sem_Ch6 is
E := Homonym (E);
exit when No (E);
- -- Warn unless genuine overloading
+ -- Warn unless genuine overloading. Do not emit warning on
+ -- hiding predefined operators in Standard (these are either an
+ -- (artifact of our implicit declarations, or simple noise) but
+ -- keep warning on a operator defined on a local subtype, because
+ -- of the real danger that different operators may be applied in
+ -- various parts of the program.
if (not Is_Overloadable (E) or else Subtype_Conformant (E, S))
and then (Is_Immediately_Visible (E)
or else
Is_Potentially_Use_Visible (S))
then
- Error_Msg_Sloc := Sloc (E);
- Error_Msg_N ("declaration of & hides one#?", S);
+ if Scope (E) /= Standard_Standard then
+ Error_Msg_Sloc := Sloc (E);
+ Error_Msg_N ("declaration of & hides one#?", S);
+
+ elsif Nkind (S) = N_Defining_Operator_Symbol
+ and then
+ Scope (
+ Base_Type (Etype (First_Formal (S)))) /= Scope (S)
+ then
+ Error_Msg_N
+ ("declaration of & hides predefined operator?", S);
+ end if;
end if;
end loop;
end if;
This patch refines the warning messages about hiding declarations of operators. If a predefined operator applies to a type declared in the current scope, there is no hiding of predefined operators (such as "=") and the warning is just misleading. If the operator is declared on a local subtype the warning is useful because it exposes the danger that different parts of a program may apply different operators to objects of the same subtype. Compiling hide.adb with -gnatwh must yield: hide.adb:13:13: warning: declaration of "=" hides predefined operator procedure hide is type Q is range 123 .. 456; type T is new Integer range 1 .. 4; subtype S is Integer range 9 .. 13; type R is record a : T; b : S; end record; function "=" (L, R : T) return Boolean is begin return False; end; function "=" (L, R : S) return Boolean is begin return False; end; function "=" (L, R : R) return Boolean is begin return False; end; function "=" (L, R : Q) return Boolean is begin return False; end; begin null; end hide; Tested on x86_64-pc-linux-gnu, committed on trunk 2010-10-21 Ed Schonberg <schonberg@adacore.com> * sem_ch6.adb (Enter_Overloaded_Entity): Refine warning message about hiding, to remove noise warnings about hiding predefined operators.