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[Ada] Crash on ignored Ghost expression function


This patch updates freezing to ensure that freeze nodes are inserted
into the tree when the entity being frozen is non-Ghost, and the context
is an ignored Ghost spec expression.

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

2018-12-11  Hristian Kirtchev  <kirtchev@adacore.com>

gcc/ada/

	* exp_util.adb (Insert_Action): Add new formal parameter
	Spec_Expr_OK.
	(Insert_Actions): Add new formal parameter Spec_Expr_OK. Update
	all calls to Insert_Actions where relevant. Honour an insertion
	from a spec expression context when requested by the caller.
	* exp_util.ads (Insert_Action): Add new formal parameter
	Spec_Expr_OK.
	(Insert_Actions): Add new formal parameter Spec_Expr_OK.
	* freeze.adb (Add_To_Result): Force the insertion of the freeze
	node even when the context is a spec expression.

gcc/testsuite/

	* gnat.dg/ghost2.adb, gnat.dg/ghost2.ads: New testcase.
--- gcc/ada/exp_util.adb
+++ gcc/ada/exp_util.adb
@@ -6702,20 +6702,34 @@ package body Exp_Util is
    -- Insert_Action --
    -------------------
 
-   procedure Insert_Action (Assoc_Node : Node_Id; Ins_Action : Node_Id) is
+   procedure Insert_Action
+     (Assoc_Node   : Node_Id;
+      Ins_Action   : Node_Id;
+      Spec_Expr_OK : Boolean := False)
+   is
    begin
       if Present (Ins_Action) then
-         Insert_Actions (Assoc_Node, New_List (Ins_Action));
+         Insert_Actions
+           (Assoc_Node   => Assoc_Node,
+            Ins_Actions  => New_List (Ins_Action),
+            Spec_Expr_OK => Spec_Expr_OK);
       end if;
    end Insert_Action;
 
    --  Version with check(s) suppressed
 
    procedure Insert_Action
-     (Assoc_Node : Node_Id; Ins_Action : Node_Id; Suppress : Check_Id)
+     (Assoc_Node   : Node_Id;
+      Ins_Action   : Node_Id;
+      Suppress     : Check_Id;
+      Spec_Expr_OK : Boolean := False)
    is
    begin
-      Insert_Actions (Assoc_Node, New_List (Ins_Action), Suppress);
+      Insert_Actions
+        (Assoc_Node   => Assoc_Node,
+         Ins_Actions  => New_List (Ins_Action),
+         Suppress     => Suppress,
+         Spec_Expr_OK => Spec_Expr_OK);
    end Insert_Action;
 
    -------------------------
@@ -6734,7 +6748,11 @@ package body Exp_Util is
    -- Insert_Actions --
    --------------------
 
-   procedure Insert_Actions (Assoc_Node : Node_Id; Ins_Actions : List_Id) is
+   procedure Insert_Actions
+     (Assoc_Node   : Node_Id;
+      Ins_Actions  : List_Id;
+      Spec_Expr_OK : Boolean := False)
+   is
       N : Node_Id;
       P : Node_Id;
 
@@ -6745,14 +6763,20 @@ package body Exp_Util is
          return;
       end if;
 
+      --  Insert the action when the context is "Handling of Default and Per-
+      --  Object Expressions" only when requested by the caller.
+
+      if Spec_Expr_OK then
+         null;
+
       --  Ignore insert of actions from inside default expression (or other
       --  similar "spec expression") in the special spec-expression analyze
       --  mode. Any insertions at this point have no relevance, since we are
       --  only doing the analyze to freeze the types of any static expressions.
-      --  See section "Handling of Default Expressions" in the spec of package
-      --  Sem for further details.
+      --  See section "Handling of Default and Per-Object Expressions" in the
+      --  spec of package Sem for further details.
 
-      if In_Spec_Expression then
+      elsif In_Spec_Expression then
          return;
       end if;
 
@@ -7429,9 +7453,10 @@ package body Exp_Util is
    --  Version with check(s) suppressed
 
    procedure Insert_Actions
-     (Assoc_Node  : Node_Id;
-      Ins_Actions : List_Id;
-      Suppress    : Check_Id)
+     (Assoc_Node   : Node_Id;
+      Ins_Actions  : List_Id;
+      Suppress     : Check_Id;
+      Spec_Expr_OK : Boolean := False)
    is
    begin
       if Suppress = All_Checks then
@@ -7439,7 +7464,7 @@ package body Exp_Util is
             Sva : constant Suppress_Array := Scope_Suppress.Suppress;
          begin
             Scope_Suppress.Suppress := (others => True);
-            Insert_Actions (Assoc_Node, Ins_Actions);
+            Insert_Actions (Assoc_Node, Ins_Actions, Spec_Expr_OK);
             Scope_Suppress.Suppress := Sva;
          end;
 
@@ -7448,7 +7473,7 @@ package body Exp_Util is
             Svg : constant Boolean := Scope_Suppress.Suppress (Suppress);
          begin
             Scope_Suppress.Suppress (Suppress) := True;
-            Insert_Actions (Assoc_Node, Ins_Actions);
+            Insert_Actions (Assoc_Node, Ins_Actions, Spec_Expr_OK);
             Scope_Suppress.Suppress (Suppress) := Svg;
          end;
       end if;

--- gcc/ada/exp_util.ads
+++ gcc/ada/exp_util.ads
@@ -89,39 +89,54 @@ package Exp_Util is
    --  calls, and this guarantee is preserved for the special cases above.
 
    procedure Insert_Action
-     (Assoc_Node : Node_Id;
-      Ins_Action : Node_Id);
+     (Assoc_Node   : Node_Id;
+      Ins_Action   : Node_Id;
+      Spec_Expr_OK : Boolean := False);
    --  Insert the action Ins_Action at the appropriate point as described
    --  above. The action is analyzed using the default checks after it is
    --  inserted. Assoc_Node is the node with which the action is associated.
+   --  When flag Spec_Expr_OK is set, insertions triggered in the context of
+   --  spec expressions are honoured, even though they contradict "Handling
+   --  of Default and Per-Object Expressions".
 
    procedure Insert_Action
-     (Assoc_Node : Node_Id;
-      Ins_Action : Node_Id;
-      Suppress   : Check_Id);
+     (Assoc_Node   : Node_Id;
+      Ins_Action   : Node_Id;
+      Suppress     : Check_Id;
+      Spec_Expr_OK : Boolean := False);
    --  Insert the action Ins_Action at the appropriate point as described
    --  above. The action is analyzed using the default checks as modified
    --  by the given Suppress argument after it is inserted. Assoc_Node is
-   --  the node with which the action is associated.
+   --  the node with which the action is associated. When flag Spec_Expr_OK
+   --  is set, insertions triggered in the context of spec expressions are
+   --  honoured, even though they contradict "Handling of Default and Per-
+   --  Object Expressions".
 
    procedure Insert_Actions
-     (Assoc_Node  : Node_Id;
-      Ins_Actions : List_Id);
+     (Assoc_Node   : Node_Id;
+      Ins_Actions  : List_Id;
+      Spec_Expr_OK : Boolean := False);
    --  Insert the list of action Ins_Actions at the appropriate point as
    --  described above. The actions are analyzed using the default checks
    --  after they are inserted. Assoc_Node is the node with which the actions
    --  are associated. Ins_Actions may be No_List, in which case the call has
-   --  no effect.
+   --  no effect. When flag Spec_Expr_OK is set, insertions triggered in the
+   --  context of spec expressions are honoured, even though they contradict
+   --  "Handling of Default and Per-Object Expressions".
 
    procedure Insert_Actions
-     (Assoc_Node  : Node_Id;
-      Ins_Actions : List_Id;
-      Suppress    : Check_Id);
+     (Assoc_Node   : Node_Id;
+      Ins_Actions  : List_Id;
+      Suppress     : Check_Id;
+      Spec_Expr_OK : Boolean := False);
    --  Insert the list of action Ins_Actions at the appropriate point as
    --  described above. The actions are analyzed using the default checks
    --  as modified by the given Suppress argument after they are inserted.
-   --  Assoc_Node is the node with which the actions are associated.
+   --  Assoc_Node is the node with which the actions are associated. List
    --  Ins_Actions may be No_List, in which case the call has no effect.
+   --  When flag Spec_Expr_OK is set, insertions triggered in the context of
+   --  spec expressions are honoured, even though they contradict "Handling
+   --  of Default and Per-Object Expressions".
 
    procedure Insert_Action_After
      (Assoc_Node : Node_Id;

--- gcc/ada/freeze.adb
+++ gcc/ada/freeze.adb
@@ -2245,13 +2245,19 @@ package body Freeze is
          --  entity being frozen is living. Insert the freezing action prior
          --  to the start of the enclosing ignored Ghost region. As a result
          --  the freezeing action will be preserved when the ignored Ghost
-         --  context is eliminated.
+         --  context is eliminated. The insertion must take place even when
+         --  the context is a spec expression, otherwise "Handling of Default
+         --  and Per-Object Expressions" will suppress the insertion, and the
+         --  freeze node will be dropped on the floor.
 
          if Saved_GM = Ignore
            and then Ghost_Mode /= Ignore
            and then Present (Ignored_Ghost_Region)
          then
-            Insert_Action (Ignored_Ghost_Region, Fnod);
+            Insert_Action
+              (Assoc_Node   => Ignored_Ghost_Region,
+               Ins_Action   => Fnod,
+               Spec_Expr_OK => True);
 
          --  Otherwise add the freezing action to the result list
 

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/ghost2.adb
@@ -0,0 +1,5 @@
+--  { dg-do compile }
+
+package body Ghost2 is
+   procedure Set is null;
+end Ghost2;

--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/ghost2.ads
@@ -0,0 +1,14 @@
+package Ghost2 is
+   type Val_Entry is (A, B, C, D);
+
+   function Transition_Valid (L : Val_Entry; R : Val_Entry) return Boolean
+   is ((L = B and R = C) or
+       (L = C and R = C) or
+       (L = C and R = D) or
+       (L = D and R = B))
+     with Ghost;
+
+   procedure Set;
+
+   type Val_Array is array (1 .. 5) of Val_Entry;
+end Ghost2;


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