Box associations are used to initialize aggregate components through the default
value of the corresponding components, or through calls to initialization
procedures. In general aggregates with such initializations cannot be built
statically. With this patch the following must compile quietly:
gcc -c -gnat05 p.adb
---
procedure P is
type A1 is array (1 .. 2, 1 .. 2) of Integer;
A : A1;
begin
A := ((1 => 2, others => <>), (others => 0));
end P;
Tested on x86_64-pc-linux-gnu, committed on trunk
2011-10-13 Ed Schonberg <schonb...@adacore.com>
* exp_aggr.adb (Flatten): If a component association has a box,
assume that aggregate is not static.
(Safe_Aggregate): If a component association in a non-limited
aggregate has a box, assume that it cannot be expanded in place.
Index: exp_aggr.adb
===================================================================
--- exp_aggr.adb (revision 179894)
+++ exp_aggr.adb (working copy)
@@ -3398,6 +3398,15 @@
begin
Assoc := First (Component_Associations (N));
while Present (Assoc) loop
+
+ -- If this is a box association, flattening is in general
+ -- not possible because at this point we cannot tell if the
+ -- default is static or even exists.
+
+ if Box_Present (Assoc) then
+ return False;
+ end if;
+
Choice := First (Choices (Assoc));
while Present (Choice) loop
@@ -4148,6 +4157,12 @@
return False;
end if;
+ -- If association has a box, no way to determine yet
+ -- whether default can be assigned in place.
+
+ elsif Box_Present (Expr) then
+ return False;
+
elsif not Safe_Component (Expression (Expr)) then
return False;
end if;
