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* [gcc r12-6233] [Ada] Prevent Get_Current_Value_Condition from returning the same node
@ 2022-01-05 11:34 Pierre-Marie de Rodat
0 siblings, 0 replies; only message in thread
From: Pierre-Marie de Rodat @ 2022-01-05 11:34 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:a6505936a35e7a5c66e36f7c4e2032c5c7f64838
commit r12-6233-ga6505936a35e7a5c66e36f7c4e2032c5c7f64838
Author: Bob Duff <duff@adacore.com>
Date: Tue Nov 30 16:00:40 2021 -0500
[Ada] Prevent Get_Current_Value_Condition from returning the same node
gcc/ada/
* exp_util.ads (Get_Current_Value_Condition): Belt: Add a
postcondition that Val /= Var.
* sem_util.adb (Known_Null): Suspenders: Raise Program_Error if
Get_Current_Value_Condition returned the same value. This will
be enabled even without assertions, because infinite recursion
is a nuisance -- better to crash if this bug ever occurs.
Diff:
---
gcc/ada/exp_util.ads | 2 +-
gcc/ada/sem_util.adb | 7 +++++++
2 files changed, 8 insertions(+), 1 deletion(-)
diff --git a/gcc/ada/exp_util.ads b/gcc/ada/exp_util.ads
index 2b61132107c..773fa01e871 100644
--- a/gcc/ada/exp_util.ads
+++ b/gcc/ada/exp_util.ads
@@ -703,7 +703,7 @@ package Exp_Util is
procedure Get_Current_Value_Condition
(Var : Node_Id;
Op : out Node_Kind;
- Val : out Node_Id);
+ Val : out Node_Id) with Post => Val /= Var;
-- This routine processes the Current_Value field of the variable Var. If
-- the Current_Value field is null or if it represents a known value, then
-- on return Cond is set to N_Empty, and Val is set to Empty.
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index 49a58e3c615..7064dfac8d8 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -22062,6 +22062,13 @@ package body Sem_Util is
Get_Current_Value_Condition (N, Op, Val);
+ -- If Get_Current_Value_Condition were to return Val = N, then the
+ -- recursion below could be infinite.
+
+ if Val = N then
+ raise Program_Error;
+ end if;
+
if Known_Null (Val) then
if Op = N_Op_Eq then
return True;
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