diff mbox series

[Ada] Fix asymmetries in detection of overlapping actuals

Message ID 20210618083827.GA129171@adacore.com
State New
Headers show
Series [Ada] Fix asymmetries in detection of overlapping actuals | expand

Commit Message

Pierre-Marie de Rodat June 18, 2021, 8:38 a.m. UTC 
When detecting overlapping actuals we were only examining the type of
the first formal parameter, so that errors and warnings were depending
on the order of parameters.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_warn.adb (Warn_On_Overlapping_Actuals): Examine types of
	both formal parameters; refactor a complex detection of
	by-reference types.
diff mbox series

Patch

diff --git a/gcc/ada/sem_warn.adb b/gcc/ada/sem_warn.adb
--- a/gcc/ada/sem_warn.adb
+++ b/gcc/ada/sem_warn.adb
@@ -3669,6 +3669,9 @@  package body Sem_Warn is
    ---------------------------------
 
    procedure Warn_On_Overlapping_Actuals (Subp : Entity_Id; N : Node_Id) is
+      function Explicitly_By_Reference (Formal_Id : Entity_Id) return Boolean;
+      --  Returns True iff the type of Formal_Id is explicitly by-reference
+
       function Refer_Same_Object
         (Act1 : Node_Id;
          Act2 : Node_Id) return Boolean;
@@ -3680,6 +3683,24 @@  package body Sem_Warn is
       --  object_name is known to refer to the same object as the other name
       --  (RM 6.4.1(6.11/3))
 
+      -----------------------------
+      -- Explicitly_By_Reference --
+      -----------------------------
+
+      function Explicitly_By_Reference
+        (Formal_Id : Entity_Id)
+         return Boolean
+      is
+         Typ : constant Entity_Id := Underlying_Type (Etype (Formal_Id));
+      begin
+         if Present (Typ) then
+            return Is_By_Reference_Type (Typ)
+              or else Convention (Typ) = Convention_Ada_Pass_By_Reference;
+         else
+            return False;
+         end if;
+      end Explicitly_By_Reference;
+
       -----------------------
       -- Refer_Same_Object --
       -----------------------
@@ -3792,17 +3813,13 @@  package body Sem_Warn is
                   then
                      null;
 
-                  --  If type is explicitly not by-copy, assume that
-                  --  aliasing is intended.
+                  --  If type is explicitly by-reference, then it is not
+                  --  covered by the legality rule, which only applies to
+                  --  elementary types. Actually, the aliasing is most
+                  --  likely intended, so don't emit a warning either.
 
-                  elsif
-                    Present (Underlying_Type (Etype (Form1)))
-                      and then
-                        (Is_By_Reference_Type
-                          (Underlying_Type (Etype (Form1)))
-                          or else
-                            Convention (Underlying_Type (Etype (Form1))) =
-                                         Convention_Ada_Pass_By_Reference)
+                  elsif Explicitly_By_Reference (Form1)
+                    or else Explicitly_By_Reference (Form2)
                   then
                      null;
 
@@ -3810,7 +3827,9 @@  package body Sem_Warn is
                   --  arrays and record types if switch is set.
 
                   elsif Ada_Version >= Ada_2012
-                    and then not Is_Elementary_Type (Etype (Form1))
+                    and then not (Is_Elementary_Type (Etype (Form1))
+                                    and then
+                                  Is_Elementary_Type (Etype (Form2)))
                     and then not Warn_On_Overlap
                   then
                      null;