Re: [PATCH] Introduce -nolibstdc++ option

[Jason Merrill <jason@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 1191 bytes --]

On 9/16/22 07:52, Jason Merrill wrote:
> On 6/24/22 01:23, Alexandre Oliva via Gcc-patches wrote:
>> On Jun 23, 2022, Alexandre Oliva <oliva@adacore.com> wrote:
>>
>>> Here's the patch.  Regstrapped on x86_64-linux-gnu, also tested with a
>>> cross to aarch64-rtems6.  Ok to install?
>>
>>> Introduce -nostdlib++ option
>>
>> Uhh, I went ahead and installed this.  The earlier patch was approved if
>> nobody objected, and so, having overcome the objection to the option
>> spelling, it ended up in my "approved" patchset.
>>
>> In case there are objections to it, please let me know, and I'll revert
>> it promptly, but I guess it makes little sense to revert it on the odd
>> change that someone does.  Thanks for your understanding.
> 
> I'm getting failures from pure-virtual1.C with
> 
> xg++: error: unrecognized command-line option '-nostdlib++'
> 
> I guess that's because it isn't handled by the specs in the way nostdlib 
> and nodefautlibs are.  Maybe the solution is to set SKIPOPT in the driver?
> 
> Are you not seeing this problem?

I started seeing this again and decided to track it down more.  It seems 
to be dependent on specs, as explained in this commit message:


[-- Attachment #2: 0001-driver-fix-validate_switches-logic.patch --]
[-- Type: text/x-patch, Size: 1450 bytes --]

From 0e74112cf494c93f170739b87ecc89b2d5d97f92 Mon Sep 17 00:00:00 2001
From: Jason Merrill <jason@redhat.com>
Date: Sun, 27 Nov 2022 14:30:14 -0500
Subject: [PATCH] driver: fix validate_switches logic
To: gcc-patches@gcc.gnu.org

Under the old logic for validate_switches, once suffix or starred got set,
they stayed set for all later switches found in the spec.  So for e.g.

%{g*:%{%:debug-level-gt(0):

Once we see g*, starred is set.  Then we see %:, and it sees that as a
zero-length switch, which because starred is still set, matches any and all
command-line options.  So targets that use such a spec accept all options in
the driver, while ones that don't reject some, such as the recent
-nostdlib++.

This patch fixes the inconsistency, so all targets reject -nostdlib++.

gcc/ChangeLog:

	* gcc.cc (validate_switches): Reset suffix/starred on loop.
---
 gcc/gcc.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/gcc/gcc.cc b/gcc/gcc.cc
index ca1c9e27a94..2278e2b6bb1 100644
--- a/gcc/gcc.cc
+++ b/gcc/gcc.cc
@@ -9299,12 +9299,15 @@ validate_switches (const char *start, bool user_spec, bool braced)
   const char *atom;
   size_t len;
   int i;
-  bool suffix = false;
-  bool starred = false;
+  bool suffix;
+  bool starred;
 
 #define SKIP_WHITE() do { while (*p == ' ' || *p == '\t') p++; } while (0)
 
 next_member:
+  suffix = false;
+  starred = false;
+
   SKIP_WHITE ();
 
   if (*p == '!')
-- 
2.31.1