On 12/5/20 7:03 AM, Bruno Haible wrote:
* The only appropriate answer that is left is
'-fsanitize=signed-integer-overflow -fsanitize-undefined-trap-on-error'.
Could we document this in the Gnulib documentation?
I gave it a shot by installing the attached patches.
There are a bunch of other flags we could mention, but it might be out of scope
for the Gnulib manual.
I'm reluctant to recommend -fsanitize=whatever flags for production builds
because they're ABI-incompatible with future library versions; at least, that's
what Florian said a couple of years ago
<https://developers.redhat.com/blog/2018/03/21/compiler-and-linker-flags-gcc/>.
Would it make sense to tell the GCC people that
- the '-fsanitize=signed-integer-overflow
-fno-sanitize-recover=signed-integer-overflow'
options are practically useless when they force a dependency towards
libstdc++,
- the 'ftrapv' option is useless when it does not work in combination with
'-O2' ?
I'm not observing the latter problem with GCC 10.2.1 (Red Hat 10.2.1-9) on
Fedora 33 x86-64; maybe it's fixed now? I didn't investigate the former problem,
but if it's an issue I suppose it's worth reporting.
From f144df31352a3912693c47995faea3c50af569db Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Sat, 5 Dec 2020 17:31:43 -0800
Subject: [PATCH 1/2] doc: mention static and dynamic checking
* doc/gnulib-readme.texi (High Quality): Add a bit of advice
for static and dynamic checking.
---
ChangeLog | 4 ++++
doc/gnulib-readme.texi | 22 ++++++++++++++++++++++
2 files changed, 26 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 72895ac78..d07d96878 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
2020-12-05 Paul Eggert <egg...@cs.ucla.edu>
+ doc: mention static and dynamic checking
+ * doc/gnulib-readme.texi (High Quality): Add a bit of advice
+ for static and dynamic checking.
+
intprops: Add INT_ADD_OK etc.
* doc/intprops.texi (Checking Integer Overflow): New section.
* lib/intprops.h: From a suggestion by Bruno Haible in:
diff --git a/doc/gnulib-readme.texi b/doc/gnulib-readme.texi
index 4775fa89a..a2a59628b 100644
--- a/doc/gnulib-readme.texi
+++ b/doc/gnulib-readme.texi
@@ -529,3 +529,25 @@ break. This means that before any change can be committed to the
repository, a test suite program must be produced that exposes the bug
for regression testing. All experimental work should be done on
branches to help promote this.
+
+When compiling and testing Gnulib and Gnulib-using programs, certain
+compiler options can help improve reliability. The
+@code{manywarnings} module enables several forms of static checking in
+GCC and related compilers (@pxref{manywarnings}). For dynamic checking,
+you can run @code{configure} with @code{CFLAGS} options appropriate
+for your compiler. For example:
+
+@example
+./configure \
+ CFLAGS='-g3 -O2'\
+' -D_FORTIFY_SOURCE=2'\
+' -fsanitize=undefined'\
+' -fsanitize-undefined-trap-on-error'
+@end example
+
+@noindent
+Here, @code{-D_FORTIFY_SOURCE=2} enables extra security hardening
+checks in the GNU C library, @code{-fsanitize=undefined} enables GCC's
+undefined behavior sanitizer (@code{ubsan}), and
+@code{-fsanitize-undefined-trap-on-error} prevents @code{ubsan}'s
+linking to unnecessary libraries like @code{libstdc++}.
--
2.27.0
From 0fcd7c693a775e3313ed3e84ff3acf3dc2c3686b Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Sat, 5 Dec 2020 17:33:29 -0800
Subject: [PATCH 2/2] doc: fix curved quotes issue
* doc/gnulib.texi: Set txicodequoteundirected and
txicodequotebacktick so that ` and ' in examples do not generate
curved single quotes that do the wrong thing when cut and pasted.
---
ChangeLog | 5 +++++
doc/gnulib.texi | 8 ++++++++
2 files changed, 13 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index d07d96878..5378f177a 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,10 @@
2020-12-05 Paul Eggert <egg...@cs.ucla.edu>
+ doc: fix curved quotes issue
+ * doc/gnulib.texi: Set txicodequoteundirected and
+ txicodequotebacktick so that ` and ' in examples do not generate
+ curved single quotes that do the wrong thing when cut and pasted.
+
doc: mention static and dynamic checking
* doc/gnulib-readme.texi (High Quality): Add a bit of advice
for static and dynamic checking.
diff --git a/doc/gnulib.texi b/doc/gnulib.texi
index 0620118bf..bddb80624 100644
--- a/doc/gnulib.texi
+++ b/doc/gnulib.texi
@@ -2,6 +2,14 @@
@comment %**start of header
@setfilename gnulib.info
@settitle GNU Gnulib
+@c These two require Texinfo 5.0 or later, so we use the older
+@c equivalent @set variables supported in 4.11 and hence
+@ignore
+@codequotebacktick on
+@codequoteundirected on
+@end ignore
+@set txicodequoteundirected
+@set txicodequotebacktick
@c Define a new index for the magic constants in regex.texi.
@defcodeindex cn
@syncodeindex fn cp
--
2.27.0
