[Ada] Crash on compilation unit function that builds in place

[Pierre-Marie de Rodat]

This patch fixes a crash on a function that builds its limited result in
place. Previously this was handled properly only if the function was a
child unit.

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

2018-12-11  Ed Schonberg  <schonb...@adacore.com>

gcc/ada/

        * sem_ch3.adb (Build_Itype_Reference): Handle properly an itype
        reference created for a function that is a compilation unit, for
        example if the function builds in place an object of a limited
        type.

gcc/testsuite/

        * gnat.dg/bip_cu.adb, gnat.dg/bip_cu_constructor.adb,
        gnat.dg/bip_cu_constructor.ads, gnat.dg/bip_cu_t.adb,
        gnat.dg/bip_cu_t.ads: New testcase.
--- gcc/ada/sem_ch3.adb
+++ gcc/ada/sem_ch3.adb
@@ -10368,12 +10368,13 @@ package body Sem_Ch3 is
          --  If Nod is a library unit entity, then Insert_After won't work,
          --  because Nod is not a member of any list. Therefore, we use
          --  Add_Global_Declaration in this case. This can happen if we have a
-         --  build-in-place library function.
+         --  build-in-place library function, child unit or not.
 
          if (Nkind (Nod) in N_Entity and then Is_Compilation_Unit (Nod))
            or else
-             (Nkind (Nod) = N_Defining_Program_Unit_Name
-               and then Is_Compilation_Unit (Defining_Identifier (Nod)))
+             (Nkind_In (Nod,
+                N_Defining_Program_Unit_Name, N_Subprogram_Declaration)
+               and then Is_Compilation_Unit (Defining_Entity (Nod)))
          then
             Add_Global_Declaration (IR);
          else

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/bip_cu.adb
@@ -0,0 +1,10 @@
+--  { dg-do compile }
+
+with BIP_CU_T; use BIP_CU_T;
+with BIP_CU_Constructor;
+
+procedure BIP_CU is
+    Value : constant T := BIP_CU_Constructor;
+begin
+    null;
+end;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/bip_cu_constructor.adb
@@ -0,0 +1,5 @@
+with BIP_CU_T; use BIP_CU_T;
+function BIP_CU_Constructor return T is
+begin
+   return Make_T (Name => "Rumplestiltskin");
+end BIP_CU_Constructor;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/bip_cu_constructor.ads
@@ -0,0 +1,2 @@
+with BIP_CU_T; use BIP_CU_T;
+function BIP_CU_Constructor return T;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/bip_cu_t.adb
@@ -0,0 +1,8 @@
+package body BIP_CU_T is
+
+   function Make_T (Name : String) return T is
+   begin
+      return (Name => To_Unbounded_String (Name), others => <>);
+   end Make_T;
+
+end BIP_CU_T;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/bip_cu_t.ads
@@ -0,0 +1,10 @@
+with Ada.Strings.Unbounded; use Ada.Strings.Unbounded;
+
+package BIP_CU_T is
+   type T is limited private;
+   function Make_T (Name : String) return T;
+private
+   type T is limited record
+      Name : Unbounded_String;
+   end record;
+end BIP_CU_T;