An aggregate can be handled by the backend if it consists of static
constants of an elementary type, or null. If a component is a type
conversion we must preanalyze and resolve it to determine whether the
ultimate value is in one of these categories. Previously we did a full
analysis and resolution of the expression for the component, which could
lead to a removal of side-effects, which is semantically incorrect if
the expression includes functions with side-effects (e.g. a call to a
random generator).
Tested on x86_64-pc-linux-gnu, committed on trunk
2019-08-13 Ed Schonberg <schonb...@adacore.com>
gcc/ada/
* exp_aggr.adb (Aggr_Assignment_OK_For_Backend): Preanalyze
expression, rather do a full analysis, to prevent unwanted
removal of side effects which mask the intent of the expression.
gcc/testsuite/
* gnat.dg/aggr27.adb: New testcase.--- gcc/ada/exp_aggr.adb
+++ gcc/ada/exp_aggr.adb
@@ -5321,6 +5321,16 @@ package body Exp_Aggr is
return False;
end if;
+ -- If the expression has side effects (e.g. contains calls with
+ -- potential side effects) reject as well. We only preanalyze the
+ -- expression to prevent the removal of intended side effects.
+
+ Preanalyze_And_Resolve (Expr, Ctyp);
+
+ if not Side_Effect_Free (Expr) then
+ return False;
+ end if;
+
-- The expression needs to be analyzed if True is returned
Analyze_And_Resolve (Expr, Ctyp);
--- /dev/null
new file mode 100644
+++ gcc/testsuite/gnat.dg/aggr27.adb
@@ -0,0 +1,26 @@
+-- { dg-do run }
+-- { dg-options "-gnatws -gnata" }
+
+with GNAT.Random_Numbers;
+
+procedure Aggr27 is
+
+ Gen: GNAT.Random_Numbers.Generator;
+
+ function Random return Long_Long_Integer is
+ Rand : Integer := GNAT.Random_Numbers.Random(Gen);
+ begin
+ return Long_Long_Integer(Rand);
+ end Random;
+
+ type Values is range 1 .. 4;
+
+ Seq_LLI : array (Values) of Long_Long_Integer := (others => Random);
+ Seq_I : array (Values) of Integer := (others => Integer(Random));
+
+begin
+ -- Verify that there is at least two different entries in each.
+
+ pragma Assert (For some E of Seq_LLI => E /= Seq_LLI (Values'First));
+ pragma Assert (For some E of Seq_I => E /= Seq_I (Values'First));
+end Aggr27;
