[gcc r12-1885] [Ada] Overriding errors on renamings and instances overriding predefined operators

[gcc r12-1885] [Ada] Overriding errors on renamings and instances overriding predefined operators

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:4c07e6d67921bb0793890550094d464153e479eb

commit r12-1885-g4c07e6d67921bb0793890550094d464153e479eb
Author: Gary Dismukes <dismukes@adacore.com>
Date:   Mon Apr 12 17:20:33 2021 -0400

    [Ada] Overriding errors on renamings and instances overriding predefined operators
    
    gcc/ada/
    
            * sem_ch6.ads (Can_Override_Operator): Function declaration
            moved from package body to package spec.
            * sem_ch6.adb (Check_Overriding_Indicator): Now use test of
            whether the subprogram's Chars is an operator name, to handle
            cases of function instances whose entity is
            N_Defining_Identifier rather than N_Defining_Operator_Symbol.
            (Can_Override_Operator): Function declaration moved to package
            spec.  Now use test of whether the subprogram's Chars is an
            operator name, to handle cases of function instances whose
            entity is N_Defining_Identifier rather than
            N_Defining_Operator_Symbol.
            * sem_ch8.adb (Analyze_Renamed_Subprogram): Check for
            possibility of an overridden predefined operator, and suppress
            the "not overriding" message in that case.

Diff:
---
 gcc/ada/sem_ch6.adb | 12 +++++++-----
 gcc/ada/sem_ch6.ads |  3 +++
 gcc/ada/sem_ch8.adb |  4 +++-
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/gcc/ada/sem_ch6.adb b/gcc/ada/sem_ch6.adb
index 7b4b288e050..c361acc4937 100644
--- a/gcc/ada/sem_ch6.adb
+++ b/gcc/ada/sem_ch6.adb
@@ -132,9 +132,6 @@ package body Sem_Ch6 is
    --  Does all the real work of Analyze_Subprogram_Body. This is split out so
    --  that we can use RETURN but not skip the debug output at the end.
 
-   function Can_Override_Operator (Subp : Entity_Id) return Boolean;
-   --  Returns true if Subp can override a predefined operator.
-
    procedure Check_Conformance
      (New_Id                   : Entity_Id;
       Old_Id                   : Entity_Id;
@@ -7321,7 +7318,7 @@ package body Sem_Ch6 is
       --  predefined signature, because we know already that there is no
       --  explicit overridden operation.
 
-      elsif Nkind (Subp) = N_Defining_Operator_Symbol then
+      elsif Chars (Subp) in Any_Operator_Name then
          if Must_Not_Override (Spec) then
 
             --  If this is not a primitive or a protected subprogram, then
@@ -8313,7 +8310,12 @@ package body Sem_Ch6 is
       Typ : Entity_Id;
 
    begin
-      if Nkind (Subp) /= N_Defining_Operator_Symbol then
+      --  Return False if not an operator. We test the name rather than testing
+      --  that the Nkind is N_Defining_Operator_Symbol, because there are cases
+      --  where an operator entity can be an N_Defining_Identifier (such as for
+      --  function instantiations).
+
+      if Chars (Subp) not in Any_Operator_Name then
          return False;
 
       else
diff --git a/gcc/ada/sem_ch6.ads b/gcc/ada/sem_ch6.ads
index 9579582763b..4afcf36c18d 100644
--- a/gcc/ada/sem_ch6.ads
+++ b/gcc/ada/sem_ch6.ads
@@ -51,6 +51,9 @@ package Sem_Ch6 is
    --  and body declarations. Returns the defining entity for the
    --  specification N.
 
+   function Can_Override_Operator (Subp : Entity_Id) return Boolean;
+   --  Returns true if Subp can override a predefined operator
+
    procedure Check_Conventions (Typ : Entity_Id);
    --  Ada 2005 (AI-430): Check that the conventions of all inherited and
    --  overridden dispatching operations of type Typ are consistent with their
diff --git a/gcc/ada/sem_ch8.adb b/gcc/ada/sem_ch8.adb
index 1c68eed693b..aa33c507575 100644
--- a/gcc/ada/sem_ch8.adb
+++ b/gcc/ada/sem_ch8.adb
@@ -3299,7 +3299,9 @@ package body Sem_Ch8 is
                Style.Missing_Overriding (N, Rename_Spec);
             end if;
 
-         elsif Must_Override (Specification (N)) then
+         elsif Must_Override (Specification (N))
+           and then not Can_Override_Operator (Rename_Spec)
+         then
             Error_Msg_NE ("subprogram& is not overriding", N, Rename_Spec);
          end if;