[Ada] Ada2020: AI12-0301 Predicates and Default_Value

Message ID 20200609081006.GA73744@adacore.com
State New
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Series
  • [Ada] Ada2020: AI12-0301 Predicates and Default_Value
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Commit Message

Pierre-Marie de Rodat June 9, 2020, 8:10 a.m.
This AI clarifies that predicate checks apply at object declaration for
types that contain components with a Default_Value or
Default_Component_Value.

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

2020-06-09  Arnaud Charlet  <charlet@adacore.com>

gcc/ada/

	* sem_util.ads, sem_util.adb (Is_Partially_Initialized_Type):
	Take Default_Value and Default_Component_Value into account.
	* sem_ch3.adb (Analyze_Object_Declaration): Update comment.

Patch

--- gcc/ada/sem_ch3.adb
+++ gcc/ada/sem_ch3.adb
@@ -4366,8 +4366,10 @@  package body Sem_Ch3 is
       --  We need a predicate check if the type has predicates that are not
       --  ignored, and if either there is an initializing expression, or for
       --  default initialization when we have at least one case of an explicit
-      --  default initial value and then this is not an internal declaration
-      --  whose initialization comes later (as for an aggregate expansion).
+      --  default initial value (including via a Default_Value or
+      --  Default_Component_Value aspect, see AI12-0301) and then this is not
+      --  an internal declaration whose initialization comes later (as for an
+      --  aggregate expansion).
       --  If expression is an aggregate it may be expanded into assignments
       --  and the declaration itself is marked with No_Initialization, but
       --  the predicate still applies.

--- gcc/ada/sem_util.adb
+++ gcc/ada/sem_util.adb
@@ -16863,7 +16863,7 @@  package body Sem_Util is
    is
    begin
       if Is_Scalar_Type (Typ) then
-         return False;
+         return Has_Default_Aspect (Base_Type (Typ));
 
       elsif Is_Access_Type (Typ) then
          return Include_Implicit;
@@ -16872,8 +16872,9 @@  package body Sem_Util is
 
          --  If component type is partially initialized, so is array type
 
-         if Is_Partially_Initialized_Type
-              (Component_Type (Typ), Include_Implicit)
+         if Has_Default_Aspect (Base_Type (Typ))
+           or else Is_Partially_Initialized_Type
+                     (Component_Type (Typ), Include_Implicit)
          then
             return True;
 

--- gcc/ada/sem_util.ads
+++ gcc/ada/sem_util.ads
@@ -1872,7 +1872,8 @@  package Sem_Util is
    --  Typ is a type entity. This function returns true if this type is partly
    --  initialized, meaning that an object of the type is at least partly
    --  initialized (in particular in the record case, that at least one
-   --  component has an initialization expression). Note that initialization
+   --  component has an initialization expression, including via Default_Value
+   --  and Default_Component_Value aspects). Note that initialization
    --  resulting from the use of pragma Normalize_Scalars does not count.
    --  Include_Implicit controls whether implicit initialization of access
    --  values to null, and of discriminant values, is counted as making the