[Ada] ICE on mix of tagged and limited interfaces

2018-09-26  Javier Miranda  <miranda@adacore.com>

gcc/ada/

	* checks.adb (Install_Null_Excluding_Check): Do not add
	null-excluding checks when the tree may not be fully decorated.
	This patch cascade errors.

From-SVN: r264619

gcc/ada/ChangeLog

+2018-09-26  Javier Miranda  <miranda@adacore.com>
+
+	* checks.adb (Install_Null_Excluding_Check): Do not add
+	null-excluding checks when the tree may not be fully decorated.
+	This patch cascade errors.
+
 2018-09-26  Gary Dismukes  <dismukes@adacore.com>
 
 	* sem_ch3.adb (Analyze_Object_Declaration): Remove test for

gcc/ada/checks.adb

@@ -7755,6 +7755,13 @@ package body Checks is
    --  Start of processing for Install_Null_Excluding_Check
 
    begin
+      --  No need to add null-excluding checks when the tree may not be fully
+      --  decorated.
+
+      if Serious_Errors_Detected > 0 then
+         return;
+      end if;
+
       pragma Assert (Is_Access_Type (Typ));
 
       --  No check inside a generic, check will be emitted in instance