[Bug driver/102803] New: Bug: -no-canonical-prefixes not working

[Bug driver/102803] New: Bug: -no-canonical-prefixes not working

[carlosgalvezp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

            Bug ID: 102803
           Summary: Bug: -no-canonical-prefixes not working
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: driver
          Assignee: unassigned at gcc dot gnu.org
          Reporter: carlosgalvezp at gmail dot com
  Target Milestone: ---

Hi,

GCC has the option "-no-canonical-prefixes" to avoid calling "realpath" on
default include search paths. This is needed when one wants to use GCC in
Bazel:

https://github.com/bazelbuild/bazel/issues/4605#issuecomment-364174051

Now, GCC as downloaded from here:

http://ppa.launchpad.net/ubuntu-toolchain-r/test/ubuntu/pool/main/g/gcc-11/g++-11_11.1.0-1ubuntu1~18.04.1_amd64.deb

does *not* honor the -no-canonical-prefixes flag.

If one unpacks the above .deb file into e.g. /path/to/gcc, and runs gcc from
there like ./usr/bin/gcc-11 with the -no-canonical-prefixes option, then the
default search paths resolve all symlinks and "../", leading to a realpath:

/path/to/gcc# ./usr/bin/gcc-11 -no-canonical-prefixes
-fno-canonical-system-headers -xc++ -E -v -

ignoring nonexistent directory
"./usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../include/x86_64-linux-gnu/c++/11/x86_64-linux-gnu"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/x86_64-linux-gnu/11/include"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/x86_64-linux-gnu/11/include-fixed"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
ignoring duplicate directory "/path/to/gcc/usr/include/c++/11"
ignoring duplicate directory "/path/to/gcc/usr/include/x86_64-linux-gnu/c++/11"
ignoring duplicate directory "/path/to/gcc/usr/include/x86_64-linux-gnu/c++/11"
ignoring duplicate directory "/path/to/gcc/usr/include/c++/11/backward"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11/include"
ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11/include-fixed"
ignoring nonexistent directory
"./usr/bin/../lib/gcc/../../lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include"
ignoring nonexistent directory "/usr/include/x86_64-linux-gnu"
#include "..." search starts here:
#include <...> search starts here:
 /path/to/gcc/usr/include/c++/11
 /path/to/gcc/usr/include/x86_64-linux-gnu/c++/11
 /path/to/gcc/usr/include/c++/11/backward
 /usr/local/include
 /usr/include

I.e. the default search paths are:

 /path/to/gcc/usr/include/c++/11
 /path/to/gcc/usr/include/x86_64-linux-gnu/c++/11
 /path/to/gcc/usr/include/c++/11/backward

Instead of:

./usr/bin/../include/c++/11

This happens also on GCC 7.

Why is this happening? Can it be solved? This prevents GCC from being used in
Bazel in a sandboxed way (i.e. without having GCC installed in the system).

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Sounds like Bazel is broken ....

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[carlosgalvezp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

--- Comment #2 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Did you read my detailed explanation and reproducible example? I took great
care and time to make the problem easy to investigate. GCC is not doing what is
supposed to do. Other compilers, like Clang, do actually apply the flag
-no-canonical-prefixes.

Putting the blame on Bazel doesn't sound like a good way to solve the problem.

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|unknown                     |11.2.0
                 CC|                            |rguenth at gcc dot gnu.org
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |WAITING
   Last reconfirmed|                            |2021-10-18

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
I get

~/install/gcc-11> ./usr/local/bin/gcc /tmp/t.c -no-canonical-prefixes
-fno-canonical-system-headers -xc++ -E -v -
Using built-in specs.
COLLECT_GCC=./usr/local/bin/gcc
Target: x86_64-pc-linux-gnu
Configured with: /home/rguenther/src/gcc-11-branch/configure
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.2.1 20210729 (GCC) 
COLLECT_GCC_OPTIONS='-fno-canonical-system-headers' '-E' '-v' '-mtune=generic'
'-march=x86-64'
 ./usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/11.2.1/cc1 -E -quiet -v
-iprefix ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/ /tmp/t.c
-mtune=generic -march=x86-64 -fno-canonical-system-headers -dumpbase t.c
-dumpbase-ext .c
ignoring nonexistent directory
"./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../x86_64-pc-linux-gnu/include"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include-fixed"
ignoring nonexistent directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include
 ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include-fixed
 /usr/local/include
 /usr/include
End of search list.
# 0 "/tmp/t.c"
# 0 "<built-in>"
# 0 "<command-line>"
# 1 "/usr/include/stdc-predef.h" 1 3 4
# 0 "<command-line>" 2
# 1 "/tmp/t.c"
int main(){}
COLLECT_GCC_OPTIONS='-fno-canonical-system-headers' '-E' '-v' '-mtune=generic'
'-march=x86-64'
 ./usr/local/bin/../lib/gcc/x86_64-pc-linux-gnu/11.2.1/cc1plus -E -quiet -v
-iprefix ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/ -D_GNU_SOURCE
- -mtune=generic -march=x86-64 -fno-canonical-system-headers -dumpbase -
ignoring nonexistent directory
"./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../x86_64-pc-linux-gnu/include"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1/x86_64-pc-linux-gnu"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1/backward"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include"
ignoring duplicate directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include-fixed"
ignoring nonexistent directory
"./usr/local/bin/../lib64/gcc/../../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:

./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1

./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1/x86_64-pc-linux-gnu

./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/../../../../include/c++/11.2.1/backward
 ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include
 ./usr/local/bin/../lib64/gcc/x86_64-pc-linux-gnu/11.2.1/include-fixed
 /usr/local/include
 /usr/include
End of search list.

which is nearly OK(?), there are hard-coded /usr/local/include and
/usr/include,
not sure why.

The behavior possibly depends on the configuration, mine is just all defaults.

Even the standard openSUSE packages work the same, with the exception of
/usr/local/include and /usr/include again:

/usr/bin> ./gcc-10 -no-canonical-prefixes -fno-canonical-system-headers -xc++
-E -v -
Using built-in specs.
COLLECT_GCC=./gcc-10
OFFLOAD_TARGET_NAMES=nvptx-none
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-suse-linux
Configured with: ../configure --prefix=/usr --infodir=/usr/share/info
--mandir=/usr/share/man --libdir=/usr/lib64 --libexecdir=/usr/lib64
--enable-languages=c,c++,objc,fortran,obj-c++,ada,go,d
--enable-offload-targets=nvptx-none, --without-cuda-driver
--enable-checking=release --disable-werror
--with-gxx-include-dir=/usr/include/c++/10 --enable-ssp --disable-libssp
--disable-libvtv --enable-cet=auto --disable-libcc1 --disable-plugin
--with-bugurl=https://bugs.opensuse.org/ --with-pkgversion='SUSE Linux'
--with-slibdir=/lib64 --with-system-zlib --enable-libstdcxx-allocator=new
--disable-libstdcxx-pch --enable-libphobos
--enable-version-specific-runtime-libs --with-gcc-major-version-only
--enable-linker-build-id --enable-linux-futex --enable-gnu-indirect-function
--program-suffix=-10 --without-system-libunwind --enable-multilib
--with-arch-32=x86-64 --with-tune=generic --build=x86_64-suse-linux
--host=x86_64-suse-linux
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 10.3.0 (SUSE Linux) 
COLLECT_GCC_OPTIONS='-fno-canonical-system-headers' '-E' '-v' '-mtune=generic'
'-march=x86-64'
 ./../lib64/gcc/x86_64-suse-linux/10/cc1plus -E -quiet -v -iprefix
./../lib64/gcc/x86_64-suse-linux/10/ -D_GNU_SOURCE - -mtune=generic
-march=x86-64 -fno-canonical-system-headers
ignoring duplicate directory
"./../lib64/gcc/../../lib64/gcc/x86_64-suse-linux/10/include"
ignoring duplicate directory
"./../lib64/gcc/../../lib64/gcc/x86_64-suse-linux/10/include-fixed"
ignoring duplicate directory
"./../lib64/gcc/../../lib64/gcc/x86_64-suse-linux/10/../../../../x86_64-suse-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 ./../lib64/gcc/x86_64-suse-linux/10/include
 ./../lib64/gcc/x86_64-suse-linux/10/include-fixed
 ./../lib64/gcc/x86_64-suse-linux/10/../../../../x86_64-suse-linux/include
 ./../lib64/gcc/../../include/c++/10
 ./../lib64/gcc/../../include/c++/10/x86_64-suse-linux
 ./../lib64/gcc/../../include/c++/10/backward
 /usr/local/include
 /usr/include
End of search list.


So can you please, instead of using Ubuntu packages, build GCC yourself so you
can report from unpatched GCC sources and with the exact configury you used?

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[carlosgalvezp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

--- Comment #4 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Thanks a lot for the detailed answer! That's very interesting, so it can
actually have to do with how the Ubuntu version has been built. I'll definitely
give it a try building locally.

Your output looks like exactly what I would expect. The remaining /usr/include
and /usr/local/include are due to the Linux system headers, which are
GCC-agnostic (I think), so it makes sense that it picks them from there.

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED
     Ever confirmed|1                           |0

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Ubuntu's GCC is built with --with-sysroot=/ which sounds like the issue here
really.  So when you install it a different directory, it uses a new sysroot of
that directory.

And GCC calls realpath on the "./usr/bin/../../" for the sysroot.

Here is the configure line for Ubuntu 1804 (aarch64)'s GCC:
Configured with: ../src/configure -v --with-pkgversion='Ubuntu/Linaro
7.4.0-1ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--program-prefix=aarch64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --with-sysroot=/ --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-libquadmath --disable-libquadmath-support --enable-plugin
--enable-default-pie --with-system-zlib --enable-multiarch
--enable-fix-cortex-a53-843419 --disable-werror --enable-checking=release
--build=aarch64-linux-gnu --host=aarch64-linux-gnu --target=aarch64-linux-gnu

So you can see the --with-sysroot=/ option.


try this:
./usr/bin/gcc -no-canonical-prefixes -print-sysroot

See what it prints.

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[carlosgalvezp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

--- Comment #6 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Hmm I don't see that in the x86 version of Ubuntu GCC:

Configured with: ../src/configure -v --with-pkgversion='Ubuntu
7.5.0-3ubuntu1~18.04' --with-bugurl=file:///usr/share/doc/gcc-7/README.Bugs
--enable-languages=c,ada,c++,go,brig,d,fortran,objc,obj-c++ --prefix=/usr
--with-gcc-major-version-only --program-suffix=-7
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu
--enable-libstdcxx-debug --enable-libstdcxx-time=yes
--with-default-libstdcxx-abi=new --enable-gnu-unique-object
--disable-vtable-verify --enable-libmpx --enable-plugin --enable-default-pie
--with-system-zlib --with-target-system-zlib --enable-objc-gc=auto
--enable-multiarch --disable-werror --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none --without-cuda-driver
--enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu
--target=x86_64-linux-gnu

Running your command prints nothing:

/path/to/gcc# ./usr/bin/gcc-7 -print-sysroot      
/path/to/gcc#

Same with:

/path/to/gcc# ./usr/bin/gcc-7 -no-canonical-prefixes -print-sysroot      
/path/to/gcc#

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The next different is multiarch .

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |doko at gcc dot gnu.org

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
CCing Matthias.

[Bug driver/102803] Bug: -no-canonical-prefixes not working

[carlosgalvezp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102803

Carlos Galvez <carlosgalvezp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |INVALID
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #9 from Carlos Galvez <carlosgalvezp at gmail dot com> ---
Ok I've built from source with a different configuration than Ubuntu's and the
-no-canonical-prefixes works as expected! So indeed it must be something in the
Ubuntu configuration. I will then go and diff the configs to get to the root of
this.

Closing the bug as it's definitely not on GCC side, sorry for the confusion and
thanks a lot for the help!