This patch fixes a spurious link error on a compilation that involves
a child unit that must be compiled with assertions enabled, and a parent
that is compiled without. The error occurs when the parent includes
instantiations that involve constructs such as predicates or pre/
postconditions, and object declarations for discriminated types with
complex discriminant constraints.
Tested on x86_64-pc-linux-gnu, committed on trunk
gcc/ada/
* exp_util.ads (Force_Evaluation): Add formal parameter
Discr_Number, to indicate discriminant expression for which an
external name must be created.
(Remove_Side_Effects): Ditto.
* exp_util.adb (Force_Evaluation): Call Remove_Side_Effects with
added parameter.
(Remove_Side_Effects, Build_Temporary): If Discr_Number is
positive, create an external name with suffix DISCR and the
given discriminant number, analogous to what is done for
temporaries for array type bounds.
* sem_ch3.adb (Process_Discriminant_Expressions): If the
constraint is for an object or component declaration and the
corresponding entity may be visible in another unit, invoke
Force_Evaluation with the new parameter.diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -6589,6 +6589,7 @@ package body Exp_Util is
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
Is_High_Bound : Boolean := False;
+ Discr_Number : Int := 0;
Mode : Force_Evaluation_Mode := Relaxed)
is
begin
@@ -6600,6 +6601,7 @@ package body Exp_Util is
Related_Id => Related_Id,
Is_Low_Bound => Is_Low_Bound,
Is_High_Bound => Is_High_Bound,
+ Discr_Number => Discr_Number,
Check_Side_Effects =>
Is_Static_Expression (Exp)
or else Mode = Relaxed);
@@ -11623,6 +11625,7 @@ package body Exp_Util is
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
Is_High_Bound : Boolean := False;
+ Discr_Number : Int := 0;
Check_Side_Effects : Boolean := True)
is
function Build_Temporary
@@ -11653,13 +11656,28 @@ package body Exp_Util is
Temp_Nam : Name_Id;
begin
- -- The context requires an external symbol
+ -- The context requires an external symbol : expression is
+ -- the bound of an array, or a discriminant value. We create
+ -- a unique string using the related entity and an appropriate
+ -- suffix, rather than a numeric serial number (used for internal
+ -- entities) that may vary depending on compilation options, in
+ -- particular on the Assertions_Enabled mode. This avoids spurious
+ -- link errors.
if Present (Related_Id) then
if Is_Low_Bound then
Temp_Nam := New_External_Name (Chars (Related_Id), "_FIRST");
- else pragma Assert (Is_High_Bound);
+
+ elsif Is_High_Bound then
Temp_Nam := New_External_Name (Chars (Related_Id), "_LAST");
+
+ else
+ pragma Assert (Discr_Number > 0);
+ -- Use fully qualified name to avoid ambiguities.
+
+ Temp_Nam :=
+ New_External_Name
+ (Get_Qualified_Name (Related_Id), "_DISCR", Discr_Number);
end if;
Temp_Id := Make_Defining_Identifier (Loc, Temp_Nam);
diff --git a/gcc/ada/exp_util.ads b/gcc/ada/exp_util.ads
--- a/gcc/ada/exp_util.ads
+++ b/gcc/ada/exp_util.ads
@@ -668,6 +668,7 @@ package Exp_Util is
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
Is_High_Bound : Boolean := False;
+ Discr_Number : Int := 0;
Mode : Force_Evaluation_Mode := Relaxed);
-- Force the evaluation of the expression right away. Similar behavior
-- to Remove_Side_Effects when Variable_Ref is set to TRUE. That is to
@@ -688,6 +689,12 @@ package Exp_Util is
-- of the Is_xxx_Bound flags must be set. For use of these parameters see
-- the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
+ -- Discr_Number is positive when the expression is a discriminant value
+ -- in an object or component declaration. In that case Discr_Number is
+ -- the position of the corresponding discriminant in the corresponding
+ -- type declaration, and the name for the evaluated expression is built
+ -- out of the Related_Id and the Discr_Number.
+
function Fully_Qualified_Name_String
(E : Entity_Id;
Append_NUL : Boolean := True) return String_Id;
@@ -1004,6 +1011,7 @@ package Exp_Util is
Related_Id : Entity_Id := Empty;
Is_Low_Bound : Boolean := False;
Is_High_Bound : Boolean := False;
+ Discr_Number : Int := 0;
Check_Side_Effects : Boolean := True);
-- Given the node for a subexpression, this function replaces the node if
-- necessary by an equivalent subexpression that is guaranteed to be side
@@ -1028,6 +1036,9 @@ package Exp_Util is
-- of the Is_xxx_Bound flags must be set. For use of these parameters see
-- the warning in the body of Sem_Ch3.Process_Range_Expr_In_Decl.
--
+ -- If Discr_Number is positive, the expression denotes a discrimant value
+ -- in a constraint, the suffix DISCR is used to create the external name.
+
-- The side effects are captured using one of the following methods:
--
-- 1) a constant initialized with the value of the subexpression
diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -10492,7 +10492,26 @@ package body Sem_Ch3 is
Apply_Range_Check (Discr_Expr (J), Etype (Discr));
end if;
- Force_Evaluation (Discr_Expr (J));
+ -- If the value of the discriminant may be visible in
+ -- another unit or child unit, create an external name
+ -- for it. We use the name of the object or component
+ -- that carries the discriminated subtype. The code
+ -- below may generate external symbols for the discriminant
+ -- expression when not strictly needed, which is harmless.
+
+ if Expander_Active
+ and then Comes_From_Source (Def)
+ and then not Is_Subprogram (Current_Scope)
+ and then Nkind (Parent (Def)) in
+ N_Object_Declaration | N_Component_Declaration
+ then
+ Force_Evaluation (
+ Discr_Expr (J),
+ Related_Id => Defining_Identifier (Parent (Def)),
+ Discr_Number => J);
+ else
+ Force_Evaluation (Discr_Expr (J));
+ end if;
end if;
-- Check that the designated type of an access discriminant's
