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[Ada] Crash on declaration with aggregate for unchecked union

Message ID 20200706113854.GA135454@adacore.com
State New
Headers show
Series [Ada] Crash on declaration with aggregate for unchecked union | expand

Commit Message

Pierre-Marie de Rodat July 6, 2020, 11:38 a.m. UTC 
This patch fixes a compiler abort on an object declaration whose
expression is an aggregate for an unchecked union type. A declaration
for an object of such a type is otherwise treated as a renaming of the
expression (typically an object of the type), but this does work for an
aggregate, which must be resolved and handled as an initial value of
a regular declaration.

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

gcc/ada/

	* sem_ch3.adb (Analyze_Object_Declaration): If the type is an
	Unchecked_Union, and the expression is an aggregate. complete
	the analysis and resolution of the aggregate, and treat like a
	regular object declaration, instead of as a renaming
	declarattion.
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Patch

diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -4564,16 +4564,26 @@  package body Sem_Ch3 is
                   Set_Ekind (Id, E_Variable);
                end if;
 
-               Rewrite (N,
-                 Make_Object_Renaming_Declaration (Loc,
-                   Defining_Identifier => Id,
-                   Subtype_Mark        => New_Occurrence_Of (T, Loc),
-                   Name                => E));
-
-               Set_Renamed_Object (Id, E);
-               Freeze_Before (N, T);
-               Set_Is_Frozen (Id);
-               goto Leave;
+               --  If the expression is an aggregate it contains the required
+               --  discriminant values but it has not been resolved yet, so do
+               --  it now, and treat it as the initial expression of an object
+               --  declaration, rather than a renaming.
+
+               if Nkind (E) = N_Aggregate then
+                  Analyze_And_Resolve (E, T);
+
+               else
+                  Rewrite (N,
+                    Make_Object_Renaming_Declaration (Loc,
+                      Defining_Identifier => Id,
+                      Subtype_Mark        => New_Occurrence_Of (T, Loc),
+                      Name                => E));
+
+                  Set_Renamed_Object (Id, E);
+                  Freeze_Before (N, T);
+                  Set_Is_Frozen (Id);
+                  goto Leave;
+               end if;
 
             else
                --  Ensure that the generated subtype has a unique external name