From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1914) id DA3D7385842E; Wed, 5 Jan 2022 11:34:07 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org DA3D7385842E MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Pierre-Marie de Rodat To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-6233] [Ada] Prevent Get_Current_Value_Condition from returning the same node X-Act-Checkin: gcc X-Git-Author: Bob Duff X-Git-Refname: refs/heads/master X-Git-Oldrev: 54403a8130c126cc3e901341dac64afbc7273347 X-Git-Newrev: a6505936a35e7a5c66e36f7c4e2032c5c7f64838 Message-Id: <20220105113407.DA3D7385842E@sourceware.org> Date: Wed, 5 Jan 2022 11:34:07 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Jan 2022 11:34:08 -0000 https://gcc.gnu.org/g:a6505936a35e7a5c66e36f7c4e2032c5c7f64838 commit r12-6233-ga6505936a35e7a5c66e36f7c4e2032c5c7f64838 Author: Bob Duff 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;