re PR ada/80590 (non-bootstrap build failure of Ada runtime)

PR ada/80590

	* sem_ch5.adb (Analyze_Loop_Statement): Avoid exception propagation
	during normal processing.

From-SVN: r272417

gcc/ada/ChangeLog

+2019-06-18  Arnaud Charlet  <charlet@adacore.com>
+
+PR ada/80590
+
+	* sem_ch5.adb (Analyze_Loop_Statement): Avoid exception propagation
+	during normal processing.
+
 2019-06-17  Arnaud Charlet  <charlet@adacore.com>
 
 PR ada/80590

gcc/ada/sem_ch5.adb

@@ -3359,8 +3359,6 @@ package body Sem_Ch5 is
       --  The following exception is raised by routine Prepare_Loop_Statement
       --  to avoid further analysis of a transformed loop.
 
-      Skip_Analysis : exception;
-
       function Disable_Constant (N : Node_Id) return Traverse_Result;
       --  If N represents an E_Variable entity, set Is_True_Constant To False
 
@@ -3368,11 +3366,12 @@ package body Sem_Ch5 is
       --  Helper for Analyze_Loop_Statement, to unset Is_True_Constant on
       --  variables referenced within an OpenACC construct.
 
-      procedure Prepare_Loop_Statement (Iter : Node_Id);
+      procedure Prepare_Loop_Statement
+        (Iter            : Node_Id;
+         Stop_Processing : out Boolean);
       --  Determine whether loop statement N with iteration scheme Iter must be
-      --  transformed prior to analysis, and if so, perform it. The routine
-      --  raises Skip_Analysis to prevent further analysis of the transformed
-      --  loop.
+      --  transformed prior to analysis, and if so, perform it.
+      --  If Stop_Processing is set to True, should stop further processing.
 
       ----------------------
       -- Disable_Constant --
@@ -3394,7 +3393,10 @@ package body Sem_Ch5 is
       -- Prepare_Loop_Statement --
       ----------------------------
 
-      procedure Prepare_Loop_Statement (Iter : Node_Id) is
+      procedure Prepare_Loop_Statement
+        (Iter            : Node_Id;
+         Stop_Processing : out Boolean)
+      is
          function Has_Sec_Stack_Default_Iterator
            (Cont_Typ : Entity_Id) return Boolean;
          pragma Inline (Has_Sec_Stack_Default_Iterator);
@@ -3414,21 +3416,27 @@ package body Sem_Ch5 is
          --  Determine whether arbitrary statement Stmt is the sole statement
          --  wrapped within some block, excluding pragmas.
 
-         procedure Prepare_Iterator_Loop (Iter_Spec : Node_Id);
+         procedure Prepare_Iterator_Loop
+           (Iter_Spec       : Node_Id;
+            Stop_Processing : out Boolean);
          pragma Inline (Prepare_Iterator_Loop);
          --  Prepare an iterator loop with iteration specification Iter_Spec
          --  for transformation if needed.
+         --  If Stop_Processing is set to True, should stop further processing.
 
-         procedure Prepare_Param_Spec_Loop (Param_Spec : Node_Id);
+         procedure Prepare_Param_Spec_Loop
+           (Param_Spec      : Node_Id;
+            Stop_Processing : out Boolean);
          pragma Inline (Prepare_Param_Spec_Loop);
          --  Prepare a discrete loop with parameter specification Param_Spec
          --  for transformation if needed.
+         --  If Stop_Processing is set to True, should stop further processing.
 
          procedure Wrap_Loop_Statement (Manage_Sec_Stack : Boolean);
-         pragma Inline    (Wrap_Loop_Statement);
-         pragma No_Return (Wrap_Loop_Statement);
+         pragma Inline (Wrap_Loop_Statement);
          --  Wrap loop statement N within a block. Flag Manage_Sec_Stack must
          --  be set when the block must mark and release the secondary stack.
+         --  Should stop further processing after calling this procedure.
 
          ------------------------------------
          -- Has_Sec_Stack_Default_Iterator --
@@ -3504,12 +3512,17 @@ package body Sem_Ch5 is
          -- Prepare_Iterator_Loop --
          ---------------------------
 
-         procedure Prepare_Iterator_Loop (Iter_Spec : Node_Id) is
+         procedure Prepare_Iterator_Loop
+           (Iter_Spec       : Node_Id;
+            Stop_Processing : out Boolean)
+         is
             Cont_Typ : Entity_Id;
             Nam      : Node_Id;
             Nam_Copy : Node_Id;
 
          begin
+            Stop_Processing := False;
+
             --  The iterator specification has syntactic errors. Transform the
             --  loop into an infinite loop in order to safely perform at least
             --  some minor analysis. This check must come first.
@@ -3517,8 +3530,7 @@ package body Sem_Ch5 is
             if Error_Posted (Iter_Spec) then
                Set_Iteration_Scheme (N, Empty);
                Analyze (N);
-
-               raise Skip_Analysis;
+               Stop_Processing := True;
 
             --  Nothing to do when the loop is already wrapped in a block
 
@@ -3578,6 +3590,7 @@ package body Sem_Ch5 is
                                    (Cont_Typ, Name_First)
                          or else Is_Sec_Stack_Iteration_Primitive
                                    (Cont_Typ, Name_Next));
+                  Stop_Processing := True;
                end if;
             end if;
          end Prepare_Iterator_Loop;
@@ -3586,7 +3599,10 @@ package body Sem_Ch5 is
          -- Prepare_Param_Spec_Loop --
          -----------------------------
 
-         procedure Prepare_Param_Spec_Loop (Param_Spec : Node_Id) is
+         procedure Prepare_Param_Spec_Loop
+           (Param_Spec      : Node_Id;
+            Stop_Processing : out Boolean)
+         is
             High     : Node_Id;
             Low      : Node_Id;
             Rng      : Node_Id;
@@ -3594,6 +3610,7 @@ package body Sem_Ch5 is
             Rng_Typ  : Entity_Id;
 
          begin
+            Stop_Processing := False;
             Rng := Discrete_Subtype_Definition (Param_Spec);
 
             --  Nothing to do when the loop is already wrapped in a block
@@ -3622,11 +3639,10 @@ package body Sem_Ch5 is
                --  on the secondary stack. Note that the loop must be wrapped
                --  only when such a call exists.
 
-               if Has_Sec_Stack_Call (Low)
-                    or else
-                  Has_Sec_Stack_Call (High)
+               if Has_Sec_Stack_Call (Low) or else Has_Sec_Stack_Call (High)
                then
                   Wrap_Loop_Statement (Manage_Sec_Stack => True);
+                  Stop_Processing := True;
                end if;
 
             --  Otherwise the parameter specification appears in the form
@@ -3663,6 +3679,7 @@ package body Sem_Ch5 is
                            and then Needs_Finalization (Rng_Typ))
                then
                   Wrap_Loop_Statement (Manage_Sec_Stack => True);
+                  Stop_Processing := True;
                end if;
             end if;
          end Prepare_Param_Spec_Loop;
@@ -3690,8 +3707,6 @@ package body Sem_Ch5 is
 
             Rewrite (N, Blk);
             Analyze (N);
-
-            raise Skip_Analysis;
          end Wrap_Loop_Statement;
 
          --  Local variables
@@ -3702,11 +3717,13 @@ package body Sem_Ch5 is
       --  Start of processing for Prepare_Loop_Statement
 
       begin
+         Stop_Processing := False;
+
          if Present (Iter_Spec) then
-            Prepare_Iterator_Loop (Iter_Spec);
+            Prepare_Iterator_Loop (Iter_Spec, Stop_Processing);
 
          elsif Present (Param_Spec) then
-            Prepare_Param_Spec_Loop (Param_Spec);
+            Prepare_Param_Spec_Loop (Param_Spec, Stop_Processing);
          end if;
       end Prepare_Loop_Statement;
 
@@ -3805,7 +3822,15 @@ package body Sem_Ch5 is
       --      wrapped within a block in order to manage the secondary stack.
 
       if Present (Iter) then
-         Prepare_Loop_Statement (Iter);
+         declare
+            Stop_Processing : Boolean;
+         begin
+            Prepare_Loop_Statement (Iter, Stop_Processing);
+
+            if Stop_Processing then
+               return;
+            end if;
+         end;
       end if;
 
       --  Kill current values on entry to loop, since statements in the body of
@@ -3979,10 +4004,6 @@ package body Sem_Ch5 is
       if Is_OpenAcc_Environment (Stmt) then
          Disable_Constants (Stmt);
       end if;
-
-   exception
-      when Skip_Analysis =>
-         null;
    end Analyze_Loop_Statement;
 
    ----------------------------