[Ada] Handle N_Others_Choice case in range-building function

Message ID 20200716092051.GA146506@adacore.com
State New
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  • [Ada] Handle N_Others_Choice case in range-building function
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Commit Message

Pierre-Marie de Rodat July 16, 2020, 9:20 a.m.
GNAT crashes when building static predicate functions out of a case
expression that contain an "others" clause. This is because it attempts
to call Is_OK_Static_Expression() on the N_Others_Choice of the case
expression when trying to figure out whether the case is exhaustive or
not.

Fixing requires two changes:

- Ensuring that choice values built out of `others` clauses have their
  Is_Static_Expression flag set.

- Checking if N is an N_Others_Choice in Membership_Entry and if it is
  returning the list of ranges that it corresponds to.

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

gcc/ada/

	* sem_case.adb (Build_Choice): Set Is_Static_Expression flag.
	(Lit_Of): Update specification to mention Is_Static_Expression
	flag.
	* sem_ch13.adb (Membership_Entry): Check for N_Others_Choice.

Patch

diff --git a/gcc/ada/sem_case.adb b/gcc/ada/sem_case.adb
--- a/gcc/ada/sem_case.adb
+++ b/gcc/ada/sem_case.adb
@@ -998,7 +998,8 @@  package body Sem_Case is
 
       function Lit_Of (Value : Uint) return Node_Id;
       --  Returns the Node_Id for the enumeration literal corresponding to the
-      --  position given by Value within the enumeration type Choice_Type.
+      --  position given by Value within the enumeration type Choice_Type. The
+      --  returned value has its Is_Static_Expression flag set to true.
 
       ------------------
       -- Build_Choice --
@@ -1016,6 +1017,7 @@  package body Sem_Case is
             if Is_Integer_Type (Choice_Type) then
                Lit_Node := Make_Integer_Literal (Loc, Value1);
                Set_Etype (Lit_Node, Choice_Type);
+               Set_Is_Static_Expression (Lit_Node);
             else
                Lit_Node := Lit_Of (Value1);
             end if;
@@ -1028,8 +1030,10 @@  package body Sem_Case is
             if Is_Integer_Type (Choice_Type) then
                Lo := Make_Integer_Literal (Loc, Value1);
                Set_Etype (Lo, Choice_Type);
+               Set_Is_Static_Expression (Lo);
                Hi := Make_Integer_Literal (Loc, Value2);
                Set_Etype (Hi, Choice_Type);
+               Set_Is_Static_Expression (Hi);
                Lit_Node :=
                  Make_Range (Loc,
                    Low_Bound  => Lo,


diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb
--- a/gcc/ada/sem_ch13.adb
+++ b/gcc/ada/sem_ch13.adb
@@ -9112,6 +9112,25 @@  package body Sem_Ch13 is
                return RList'(1 => REnt'(SLo, SHi));
             end if;
 
+         --  Others case
+
+         elsif Nkind (N) = N_Others_Choice then
+            declare
+               Choices    : constant List_Id := Others_Discrete_Choices (N);
+               Choice     : Node_Id;
+               Range_List : RList (1 .. List_Length (Choices));
+
+            begin
+               Choice := First (Choices);
+
+               for J in Range_List'Range loop
+                  Range_List (J) := REnt'(Lo_Val (Choice), Hi_Val (Choice));
+                  Next (Choice);
+               end loop;
+
+               return Range_List;
+            end;
+
          --  Static expression case
 
          elsif Is_OK_Static_Expression (N) then