[Ada] Crash on aggregate with dscriminant in if-expression as default

This patch fixes a crash on a an aggregate for a discriminated type,
when a component of the aggregate is also a discriminated type
constrained by a discriminant of the enclosing object, and the default
value for the component is a conditional expression that includes
references to that outer discriminant.

2019-09-18  Ed Schonberg  <schonberg@adacore.com>

gcc/ada/

	* exp_aggr.adb (Expand_Record_Aggregate, Rewrite_Discriminant):
	After rewriting a reference to an outer discriminant as a
	selected component of the enclosing object, analyze the selected
	component to ensure that the entity of the selector name is
	properly set. This is necessary when the aggregate appears
	within an expression that may have been analyzed already.

gcc/testsuite/

	* gnat.dg/discr58.adb: New testcase.

From-SVN: r275862

gcc/ada/ChangeLog

+2019-09-18  Ed Schonberg  <schonberg@adacore.com>
+
+	* exp_aggr.adb (Expand_Record_Aggregate, Rewrite_Discriminant):
+	After rewriting a reference to an outer discriminant as a
+	selected component of the enclosing object, analyze the selected
+	component to ensure that the entity of the selector name is
+	properly set. This is necessary when the aggregate appears
+	within an expression that may have been analyzed already.
+
 2019-09-18  Justin Squirek  <squirek@adacore.com>
 
 	* sem_ch8.adb (Use_One_Type): Add guard to prevent warning on a

gcc/ada/exp_aggr.adb

@@ -3103,6 +3103,13 @@ package body Exp_Aggr is
               Make_Selected_Component (Loc,
                 Prefix        => New_Copy_Tree (Lhs),
                 Selector_Name => Make_Identifier (Loc, Chars (Expr))));
+
+            --  The generated code will be reanalyzed, but if the reference
+            --  to the discriminant appears within an already analyzed
+            --  expression (e.g. a conditional) we must set its proper entity
+            --  now. Context is an initialization procedure.
+
+            Analyze (Expr);
          end if;
 
          return OK;

gcc/testsuite/ChangeLog

+2019-09-18  Ed Schonberg  <schonberg@adacore.com>
+
+	* gnat.dg/discr58.adb: New testcase.
+
 2019-09-18  Justin Squirek  <squirek@adacore.com>
 
 	* gnat.dg/warn30.adb, gnat.dg/warn30.ads: New testcase.

gcc/testsuite/gnat.dg/discr58.adb

+--  { dg-do compile }
+
+with Ada.Text_IO; use Ada.Text_IO;
+
+procedure Discr58 is
+
+   type Field(Flag : Boolean := True) is record
+      case Flag is
+         when True  => Param1 : Boolean := False;
+         when False => Param2 : Boolean := True;
+      end case;
+   end record;
+
+   type Header(Flag : Boolean := True) is record
+      Param3 : Integer     := 0;
+      Params : Field(Flag) := (if Flag = True then
+                                  (Flag => True, others => <>)
+                               else
+                                  (Flag => False, others => <>));
+   end record;
+
+   type Message(Flag : Boolean) is record
+
+      -- This assignment crashes GNAT
+      The_Header : Header(Flag) := Header'(Flag => True, others => <>);
+   end record;
+
+   It : Message (True);
+begin
+   Put_Line("Hello World");
+   Put_Line (Boolean'Image (It.The_Header.Flag));
+   Put_Line (Boolean'Image (It.The_Header.Params.Flag));
+end Discr58;
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