GNU bug report logs - #75620
[PATCH core-packages-team] gnu: gcc-6: Use libstdc++ headers appropriate for each GCC.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Leo Nikkilä <hello <at> lnikki.la>
To: guix-patches <at> gnu.org
Cc: Leo Nikkilä <hello <at> lnikki.la>
Subject: [PATCH core-packages-team] gnu: gcc-6: Use libstdc++ headers
 appropriate for each GCC.
Date: Fri, 17 Jan 2025 05:08:49 +0200

After the "hack" introduced for <https://issues.guix.gnu.org/42392>, all GCCs
are built with the current GCC's libstdc++ headers. This results in subtly
broken C++ headers in older versions, which aren't necessarily compatible with
libstdc++s from other versions.

For example, this test case works with GCC 11:

    $ guix shell --container --emulate-fhs --pure -e '(@ (gnu packages gcc) gcc)' binutils -- sh -c 'echo -e "#include <cmath>\nint main() { return std::isnan(0); }" | g++ -x c++ -; echo $?'
    0

but fails with GCC 9:

    $ guix shell --container --emulate-fhs --pure -e '(@ (gnu packages gcc) gcc-9)' binutils -- sh -c 'echo -e "#include <cmath>\nint main() { return std::isnan(0); }" | g++ -x c++ -; echo $?'
    
    In file included from /gnu/store/gkh2rljdrnj24q1q7baa6bhb119251w4-profile/include/c++/cmath:45,
                     from <stdin>:1:
    <stdin>: In function 'int main()':
    <stdin>:2:26: error: '__builtin_isnan' is not a member of 'std'; did you mean '__builtin_isnan'?
    <built-in>: note: '__builtin_isnan' declared here
    1

This specific error can be traced back to the GCC build, where GCC 10 and 11
are configured with:

    checking for ISO C99 support in <math.h> for C++11... yes

but GCC 9 is configured with:

    checking for ISO C99 support in <math.h> for C++11... no

The configure check fails due to errors like these due to the mismatched
libstdc++:

    configure:17817: checking for ISO C99 support in <math.h> for C++11
    configure:17886:  /tmp/guix-build-gcc-9.5.0.drv-0/build/./gcc/xgcc -shared-libgcc -B/tmp/guix-build-gcc-9.5.0.drv-0/build/./gcc -nostdinc++ -L/tmp/guix-build-gcc-9.5.0.drv-0/build/aarch64-unknown-linux-gnu/libstdc++-v3/src -L/tmp/guix-build-gcc-9.5.0.drv-0/build/aarch64-unknown-linux-gnu/libstdc++-v3/src/.libs -L/tmp/guix-build-gcc-9.5.0.drv-0/build/aarch64-unknown-linux-gnu/libstdc++-v3/libsupc++/.libs -B/gnu/store/l9a96zpznir4bm02lsycj35q0pakln32-gcc-9.5.0/aarch64-unknown-linux-gnu/bin/ -B/gnu/store/l9a96zpznir4bm02lsycj35q0pakln32-gcc-9.5.0/aarch64-unknown-linux-gnu/lib/ -isystem /gnu/store/l9a96zpznir4bm02lsycj35q0pakln32-gcc-9.5.0/aarch64-unknown-linux-gnu/include -isystem /gnu/store/l9a96zpznir4bm02lsycj35q0pakln32-gcc-9.5.0/aarch64-unknown-linux-gnu/sys-include   -fchecking=1 -o conftest -g -O2 -D_GNU_SOURCE -std=c++11 -fno-exceptions  -B/gnu/store/3gvs8sw95ldfypr1n688svl5brwdmdi9-glibc-2.39/lib -Wl,-dynamic-linker -Wl,/gnu/store/3gvs8sw95ldfypr1n688svl5brwdmdi9-glibc-2.39/lib/ld-linux-aarch64.so.1 conftest.cpp  -lm >&5
    In file included from /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/cmath:41,
                     from /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/math.h:36,
                     from conftest.cpp:41:
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:491:18: error: missing binary operator before token "("
      491 | #if __has_builtin(__builtin_is_constant_evaluated)
          |                  ^
    In file included from /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/cmath:41,
                     from /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/math.h:36,
                     from conftest.cpp:41:
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:732:25: error: missing binary operator before token "("
      732 | #if _GLIBCXX_HAS_BUILTIN(__has_unique_object_representations)
          |                         ^
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:736:25: error: missing binary operator before token "("
      736 | #if _GLIBCXX_HAS_BUILTIN(__is_aggregate)
          |                         ^
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:740:25: error: missing binary operator before token "("
      740 | #if _GLIBCXX_HAS_BUILTIN(__builtin_is_constant_evaluated)
          |                         ^
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:744:25: error: missing binary operator before token "("
      744 | #if _GLIBCXX_HAS_BUILTIN(__is_same)
          |                         ^
    /gnu/store/y3kk0ybf7hqwndl8xpm61r4a5b3lhwix-libstdc++-11.4.0/include/bits/c++config.h:748:25: error: missing binary operator before token "("
      748 | #if _GLIBCXX_HAS_BUILTIN(__builtin_launder)
          |                         ^
    configure:17886: $? = 1

Updating libstdc++ to reference each GCC works around this. I've tested this
with GCC 9, but I swapped the `libstdc++-headers' input directly as I didn't
have the time to do a `guix pull'. I wrote this little test however to check
that `this-package' should work here:

    (use-modules (guix build-system trivial)
                 (guix gexp)
                 (guix packages))
    
    (define (make-requirement pkg)
      (define builder
        #~(call-with-output-file #$output
            (lambda (port)
              (format port "~a~%" #$(package-name pkg)))))
    
      (computed-file "requirement" builder))
    
    (define package-1
      (package
        (name "package-1")
        (version "1")
        (source #f)
        (build-system trivial-build-system)
        (inputs
         `(("requirement" ,(make-requirement this-package))))
        (arguments
         '(#:builder
           (copy-file (assoc-ref %build-inputs "requirement")
                      %output)))
        (synopsis #f)
        (description #f)
        (home-page #f)
        (license #f)))
    
    (define package-2
      (package
        (inherit package-1)
        (name "package-2")
        (version "2")))
    
    (list package-1 package-2)

Building these packages results in the expected output, where each package
uses an input customised for it:

    $ cat $(guix build -f this-package.scm)
    package-2
    package-1

* gnu/packages/gcc.scm (libstdc++, libstdc++-headers): Remove variables.
(make-libstdc++-headers): New procedure.
(gcc-6)[native-inputs]: Use it with `this-package'.
---
 gnu/packages/gcc.scm | 38 ++++++++++++++++++--------------------
 1 file changed, 18 insertions(+), 20 deletions(-)

diff --git a/gnu/packages/gcc.scm b/gnu/packages/gcc.scm
index 6247919fec4..3735a9c9d94 100644
--- a/gnu/packages/gcc.scm
+++ b/gnu/packages/gcc.scm
@@ -17,6 +17,7 @@
 ;;; Copyright © 2023 Bruno Victal <mirai <at> makinata.eu>
 ;;; Copyright © 2023 Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
 ;;; Copyright © 2024 Nguyễn Gia Phong <mcsinyx <at> disroot.org>
+;;; Copyright © 2025 Leo Nikkilä <hello <at> lnikki.la>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -549,7 +550,7 @@ (define-public gcc-6
        ;; XXX: This gross hack allows us to have libstdc++'s <bits/c++config.h>
        ;; in the search path, thereby avoiding misconfiguration of libstdc++:
        ;; <https://bugs.gnu.org/42392>.
-       ("libstdc++" ,libstdc++-headers)
+       ("libstdc++" ,(make-libstdc++-headers this-package))
 
        ,@(package-inputs gcc-4.7)))))
 
@@ -1055,31 +1056,28 @@ (define-public (make-libstdc++ gcc)
     (propagated-inputs '())
     (synopsis "GNU C++ standard library")))
 
-(define libstdc++
-  ;; Libstdc++ matching the default GCC.
-  (make-libstdc++ gcc))
-
-(define libstdc++-headers
+(define (make-libstdc++-headers gcc)
   ;; XXX: This package is for internal use to work around
   ;; <https://bugs.gnu.org/42392> (see above).  The main difference compared
   ;; to the libstdc++ headers that come with 'gcc' is that <bits/c++config.h>
   ;; is right under include/c++ and not under
   ;; include/c++/x86_64-unknown-linux-gnu (aka. GPLUSPLUS_TOOL_INCLUDE_DIR).
-  (package
-    (inherit libstdc++)
-    (name "libstdc++-headers")
-    (outputs '("out"))
-    (build-system trivial-build-system)
-    (arguments
-     '(#:builder (let* ((out       (assoc-ref %outputs "out"))
-                        (libstdc++ (assoc-ref %build-inputs "libstdc++")))
-                   (mkdir out)
-                   (mkdir (string-append out "/include"))
-                   (symlink (string-append libstdc++ "/include")
-                            (string-append out "/include/c++")))))
-    (inputs `(("libstdc++" ,libstdc++)))
-    (synopsis "Headers of GNU libstdc++")))
+  (let ((libstdc++ (make-libstdc++ gcc)))
+    (package
+      (inherit libstdc++)
+      (name "libstdc++-headers")
+      (outputs '("out"))
+      (build-system trivial-build-system)
+      (arguments
+       '(#:builder (let* ((out       (assoc-ref %outputs "out"))
+                          (libstdc++ (assoc-ref %build-inputs "libstdc++")))
+                     (mkdir out)
+                     (mkdir (string-append out "/include"))
+                     (symlink (string-append libstdc++ "/include")
+                              (string-append out "/include/c++")))))
+      (inputs `(("libstdc++" ,libstdc++)))
+      (synopsis "Headers of GNU libstdc++"))))
 
 (define-public libstdc++-4.9
   (make-libstdc++ gcc-4.9))

-- 
2.47.1

Message #10 received at 75620-done <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: Leo Nikkilä <hello <at> lnikki.la>
Cc: 75620-done <at> debbugs.gnu.org
Subject: Re: bug#75620: [PATCH core-packages-team] gnu: gcc-6: Use libstdc++
 headers appropriate for each GCC.
Date: Fri, 11 Apr 2025 11:49:08 +0200

[Message part 1 (text/plain, inline)]

Hi Leo,

Leo Nikkilä <hello <at> lnikki.la> skribis:

> After the "hack" introduced for <https://issues.guix.gnu.org/42392>, all GCCs
> are built with the current GCC's libstdc++ headers. This results in subtly
> broken C++ headers in older versions, which aren't necessarily compatible with
> libstdc++s from other versions.

[...]

> * gnu/packages/gcc.scm (libstdc++, libstdc++-headers): Remove variables.
> (make-libstdc++-headers): New procedure.
> (gcc-6)[native-inputs]: Use it with `this-package'.
> ---
>  gnu/packages/gcc.scm | 38 ++++++++++++++++++--------------------
>  1 file changed, 18 insertions(+), 20 deletions(-)

Somehow this patch fell into the cracks.

I’ve now applied it with the change below (using ‘mlambdaq’ for
‘make-libstdc++-headers’); I also shortened the commit log.

Thanks!

Ludo’.

[Message part 2 (text/x-patch, inline)]

diff --git a/gnu/packages/gcc.scm b/gnu/packages/gcc.scm
index 0eec6452f6..5273aa2ce3 100644
--- a/gnu/packages/gcc.scm
+++ b/gnu/packages/gcc.scm
@@ -52,6 +52,7 @@ (define-module (gnu packages gcc)
   #:use-module (gnu packages perl)
   #:use-module (guix packages)
   #:use-module (guix download)
+  #:use-module (guix memoization)
   #:use-module (guix build-system gnu)
   #:use-module (guix build-system trivial)
   #:use-module (guix gexp)
@@ -1081,27 +1082,28 @@ (define-public (make-libstdc++ gcc)
     (propagated-inputs '())
     (synopsis "GNU C++ standard library")))
 
-(define (make-libstdc++-headers gcc)
-  ;; XXX: This package is for internal use to work around
-  ;; <https://bugs.gnu.org/42392> (see above).  The main difference compared
-  ;; to the libstdc++ headers that come with 'gcc' is that <bits/c++config.h>
-  ;; is right under include/c++ and not under
-  ;; include/c++/x86_64-unknown-linux-gnu (aka. GPLUSPLUS_TOOL_INCLUDE_DIR).
-  (let ((libstdc++ (make-libstdc++ gcc)))
-    (package
-      (inherit libstdc++)
-      (name "libstdc++-headers")
-      (outputs '("out"))
-      (build-system trivial-build-system)
-      (arguments
-       '(#:builder (let* ((out       (assoc-ref %outputs "out"))
-                          (libstdc++ (assoc-ref %build-inputs "libstdc++")))
-                     (mkdir out)
-                     (mkdir (string-append out "/include"))
-                     (symlink (string-append libstdc++ "/include")
-                              (string-append out "/include/c++")))))
-      (inputs `(("libstdc++" ,libstdc++)))
-      (synopsis "Headers of GNU libstdc++"))))
+(define make-libstdc++-headers
+  (mlambdaq (gcc)      ;memoize to play well with the object cache
+    ;; XXX: This package is for internal use to work around
+    ;; <https://bugs.gnu.org/42392> (see above).  The main difference compared
+    ;; to the libstdc++ headers that come with 'gcc' is that <bits/c++config.h>
+    ;; is right under include/c++ and not under
+    ;; include/c++/x86_64-unknown-linux-gnu (aka. GPLUSPLUS_TOOL_INCLUDE_DIR).
+    (let ((libstdc++ (make-libstdc++ gcc)))
+      (package
+        (inherit libstdc++)
+        (name "libstdc++-headers")
+        (outputs '("out"))
+        (build-system trivial-build-system)
+        (arguments
+         '(#:builder (let* ((out       (assoc-ref %outputs "out"))
+                            (libstdc++ (assoc-ref %build-inputs "libstdc++")))
+                       (mkdir out)
+                       (mkdir (string-append out "/include"))
+                       (symlink (string-append libstdc++ "/include")
+                                (string-append out "/include/c++")))))
+        (inputs `(("libstdc++" ,libstdc++)))
+        (synopsis "Headers of GNU libstdc++")))))
 
 (define-public libstdc++-4.9
   (make-libstdc++ gcc-4.9))

Message #13 received at 75620 <at> debbugs.gnu.org (full text, mbox):

From: Greg Hogan <code <at> greghogan.com>
To: 75620 <at> debbugs.gnu.org, ludo <at> gnu.org, hello <at> lnikki.la
Subject: Re: bug#75620: [PATCH core-packages-team] gnu: gcc-6: Use libstdc++
 headers appropriate for each GCC.
Date: Tue, 15 Apr 2025 09:39:01 -0400

On Fri, Apr 11, 2025 at 5:50 AM Ludovic Courtès <ludo <at> gnu.org> wrote:
>
> Hi Leo,
>
> Leo Nikkilä <hello <at> lnikki.la> skribis:
>
> > After the "hack" introduced for <https://issues.guix.gnu.org/42392>, all GCCs
> > are built with the current GCC's libstdc++ headers. This results in subtly
> > broken C++ headers in older versions, which aren't necessarily compatible with
> > libstdc++s from other versions.
>
> [...]
>
> > * gnu/packages/gcc.scm (libstdc++, libstdc++-headers): Remove variables.
> > (make-libstdc++-headers): New procedure.
> > (gcc-6)[native-inputs]: Use it with `this-package'.
> > ---
> >  gnu/packages/gcc.scm | 38 ++++++++++++++++++--------------------
> >  1 file changed, 18 insertions(+), 20 deletions(-)
>
> Somehow this patch fell into the cracks.
>
> I’ve now applied it with the change below (using ‘mlambdaq’ for
> ‘make-libstdc++-headers’); I also shortened the commit log.
>
> Thanks!
>
> Ludo’.

With this patch I now get build errors on gcc older than 14. CI is
returning 504 when viewing evaluations, but I am getting:

libtool: compile:  g++
-I/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/libstdc++-v3/../libgcc
-I/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/build/include/
-I/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/build/include
-I/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/libstdc++-v3/libsupc++
-D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra
-Wwrite-strings -Wcast-qual -Wabi=2 -fdiagnostics-show-location=once
-ffunction-sections -fdata-sections -frandom-seed=eh_call.lo
-fcf-protection -mshstk -c ../../libstdc++-v3/libsupc++/eh_call.cc
-fPIC -DPIC -D_GLIBCXX_SHARED -o eh_call.o
../../libstdc++-v3/libsupc++/eh_call.cc:39:1: warning: new declaration
‘void __cxa_call_terminate(_Unwind_Exception*)’ ambiguates built-in
declaration ‘void __cxa_call_terminate(void*)’
[-Wbuiltin-declaration-mismatch]
   39 | __cxa_call_terminate(_Unwind_Exception* ue_header) throw ()
      | ^~~~~~~~~~~~~~~~~~~~
../../libstdc++-v3/libsupc++/eh_call.cc: In function ‘void
__cxa_call_terminate(_Unwind_Exception*)’:
../../libstdc++-v3/libsupc++/eh_call.cc:39:1: internal compiler error:
in gimple_build_eh_must_not_throw, at gimple.cc:730
0x7ffff7ced956 __libc_start_call_main
        ???:0
0x7ffff7ceda14 __libc_start_main_alias_1
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
make[2]: *** [Makefile:777: eh_call.lo] Error 1
make[2]: Leaving directory
'/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/build/libsupc++'
make[1]: *** [Makefile:576: all-recursive] Error 1
make[1]: Leaving directory
'/tmp/guix-build-libstdc++-13.3.0.drv-0/gcc-13.3.0/build'
make: *** [Makefile:501: all] Error 2

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