From: Ronan Desplanques <desplanques@adacore.com>
Date: Mon, 21 Aug 2023 11:35:37 +0000 (+0200)
Subject: ada: Fix spurious warning emissions
X-Git-Tag: basepoints/gcc-15~6447
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=9be6a698f95f94a27307208cdb90bd2018182071;p=thirdparty%2Fgcc.git

ada: Fix spurious warning emissions

Before this patch, warnings handled by `Sem_Warn.Check_References` were
erroneously emitted in some cases. Here is an example of a program that,
when compiled with the `-gnatwu` switch, triggered the bug:

    procedure Main is
       package T is
          A : Integer;
       end T;
    begin
       T.A := 7;
    end Main;

The following message was emitted:

   main.adb:3:07: warning: variable "A" is never read and never assigned [-gnatwu]

This patch mitigates the issue by restricting the cases in which
`Sem_Warn.Check_References` is called for package specifications.

Note that the recursive calls in `Sem_Warn.Check_References` can be used
to convince oneself that this patch does not remove legitimate warnings
for non-library-level package specifications.

gcc/ada/

	* sem_ch7.adb (Analyze_Package_Declaration): Restrict calls to
	`Sem_Warn.Check_References` and adjust comment accordingly.
---

diff --git a/gcc/ada/sem_ch7.adb b/gcc/ada/sem_ch7.adb
index ecb4bbe3e569..1a49a53ad63b 100644
--- a/gcc/ada/sem_ch7.adb
+++ b/gcc/ada/sem_ch7.adb
@@ -1267,12 +1267,17 @@ package body Sem_Ch7 is
                Is_Main_Unit => Parent (N) = Cunit (Main_Unit));
          end if;
 
-         --  Warn about references to unset objects, which is straightforward
-         --  for packages with no bodies. For packages with bodies this is more
-         --  complicated, because some of the objects might be set between spec
-         --  and body elaboration, in nested or child packages, etc.
-
-         Check_References (Id);
+         --  For package declarations at the library level, warn about
+         --  references to unset objects, which is straightforward for packages
+         --  with no bodies. For packages with bodies this is more complicated,
+         --  because some of the objects might be set between spec and body
+         --  elaboration, in nested or child packages, etc. Note that the
+         --  recursive calls in Check_References will handle nested package
+         --  specifications.
+
+         if Is_Library_Level_Entity (Id) then
+            Check_References (Id);
+         end if;
       end if;
 
       --  Set Body_Required indication on the compilation unit node