From 3340a7acff26413f967cd6909e1fc8b9cb1839ef Mon Sep 17 00:00:00 2001
From: Fabien Chouteau <Fabien-Chouteau@users.noreply.github.com>
Date: Wed, 10 Jun 2020 17:25:07 +0200
Subject: [PATCH] Move the Alr.Main exception handler to a last chance handler
 (#442)

* Move the Alr.Main exception handler to a last chance handler

This way the exceptions raised during elaboration will also be caught.

#441

* Alr.Main: restore an exception handler to catch after elaboration

Relying only on the __gnat_last_chance_handler means that an extra backtrace
is printed by the GNAT run-time (with Notify_Unhandled_Exception).
---
 src/alr/alr-main.adb            | 11 +++--------
 src/alr/last_chance_handler.adb | 14 ++++++++++++++
 src/alr/last_chance_handler.ads |  4 ++++
 3 files changed, 21 insertions(+), 8 deletions(-)
 create mode 100644 src/alr/last_chance_handler.adb
 create mode 100644 src/alr/last_chance_handler.ads

diff --git a/src/alr/alr-main.adb b/src/alr/alr-main.adb
index 89aaf964..1018bada 100644
--- a/src/alr/alr-main.adb
+++ b/src/alr/alr-main.adb
@@ -1,13 +1,13 @@
 with Alire;
 with Alire_Early_Elaboration; pragma Elaborate_All (Alire_Early_Elaboration);
-with Alire.Errors;
 
 with Alr.Bootstrap;
 with Alr.Commands;
-with Alr.OS_Lib;
 with Alr.Platform.Init;
 with Alr.Platforms.Current;
 
+with Last_Chance_Handler;
+
 procedure Alr.Main is
 begin
    Alr.Platform.Init (Alr.Platforms.Current.New_Platform);
@@ -16,11 +16,6 @@ begin
 
    Commands.Execute;
 exception
-   --  Ensure we do not show an exception trace to unsuspecting users
    when E : others =>
-      Alire.Log_Exception (E);
-      Trace.Error (Alire.Errors.Get (E));
-      Trace.Error ("alr encountered an unexpected error,"
-                   & " re-run with -d for details.");
-      OS_Lib.Bailout (1);
+      Last_Chance_Handler (E);
 end Alr.Main;
diff --git a/src/alr/last_chance_handler.adb b/src/alr/last_chance_handler.adb
new file mode 100644
index 00000000..f8e39728
--- /dev/null
+++ b/src/alr/last_chance_handler.adb
@@ -0,0 +1,14 @@
+with Alire.Errors;
+
+with Alr;
+with Alr.OS_Lib;
+
+procedure Last_Chance_Handler (E : Ada.Exceptions.Exception_Occurrence) is
+begin
+   --  Ensure we do not show an exception trace to unsuspecting users
+   Alire.Log_Exception (E);
+   Alr.Trace.Error (Alire.Errors.Get (E));
+   Alr.Trace.Error ("alr encountered an unexpected error,"
+                    & " re-run with -d for details.");
+   Alr.OS_Lib.Bailout (1);
+end Last_Chance_Handler;
diff --git a/src/alr/last_chance_handler.ads b/src/alr/last_chance_handler.ads
new file mode 100644
index 00000000..eeb015c6
--- /dev/null
+++ b/src/alr/last_chance_handler.ads
@@ -0,0 +1,4 @@
+with Ada.Exceptions;
+
+procedure Last_Chance_Handler (E : Ada.Exceptions.Exception_Occurrence);
+pragma Export (C, Last_Chance_Handler, "__gnat_last_chance_handler");
-- 
2.39.5