[PATCH v2] gn: remove gcc override

[PATCH v2] gn: remove gcc override

[Jon Mason]

When compiling gn with clang, the following errors are being seen (with
qemuarm64-secureboot machine, possibly others):

In file included from /usr/include/c++/12/string:40,
                 from ../sources/gn-0+git/src/base/strings/string_number_conversions.h:11,
                 from ../sources/gn-0+git/src/gn/operators.cc:10:
In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
    inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
    inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:202:17:
/usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
  354 |         __c1 = __c2;
      |                ^~~~
../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
  198 |   std::string empty_def;
      |               ^~~~~~~~~
In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
    inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
    inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
    inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:205:17:
/usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
  354 |         __c1 = __c2;
      |                ^~~~
../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
  198 |   std::string empty_def;
      |               ^~~~~~~~~
cc1plus: all warnings being treated as errors

Remove the toolchain-gcc override to allow the cflag
-Wno-error=maybe-uninitialized to be applied.

Signed-off-by: Jon Mason <jon.mason@arm.com>
---
 meta/recipes-devtools/gn/gn_git.bb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/meta/recipes-devtools/gn/gn_git.bb b/meta/recipes-devtools/gn/gn_git.bb
index d8896609b193..87ccfe370456 100644
--- a/meta/recipes-devtools/gn/gn_git.bb
+++ b/meta/recipes-devtools/gn/gn_git.bb
@@ -49,4 +49,4 @@ BBCLASSEXTEND = "native"
 
 COMPATIBLE_HOST = "^(?!riscv32).*"
 
-CFLAGS:append:toolchain-gcc = " -Wno-error=maybe-uninitialized"
+CFLAGS += "-Wno-error=maybe-uninitialized"
-- 
2.39.5

Re: [OE-core] [PATCH v2] gn: remove gcc override

[Khem Raj]

On Sat, Oct 4, 2025 at 9:00 AM Jon Mason via lists.openembedded.org
<jdmason=kudzu.us@lists.openembedded.org> wrote:
>
> When compiling gn with clang, the following errors are being seen (with
> qemuarm64-secureboot machine, possibly others):
>
> In file included from /usr/include/c++/12/string:40,
>                  from ../sources/gn-0+git/src/base/strings/string_number_conversions.h:11,
>                  from ../sources/gn-0+git/src/gn/operators.cc:10:
> In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
>     inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
>     inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:202:17:
> /usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
>   354 |         __c1 = __c2;
>       |                ^~~~
> ../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
> ../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
>   198 |   std::string empty_def;
>       |               ^~~~~~~~~
> In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
>     inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
>     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
>     inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:205:17:
> /usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
>   354 |         __c1 = __c2;
>       |                ^~~~
> ../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
> ../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
>   198 |   std::string empty_def;
>       |               ^~~~~~~~~
> cc1plus: all warnings being treated as errors
>
> Remove the toolchain-gcc override to allow the cflag
> -Wno-error=maybe-uninitialized to be applied.
>
> Signed-off-by: Jon Mason <jon.mason@arm.com>
> ---
>  meta/recipes-devtools/gn/gn_git.bb | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/meta/recipes-devtools/gn/gn_git.bb b/meta/recipes-devtools/gn/gn_git.bb
> index d8896609b193..87ccfe370456 100644
> --- a/meta/recipes-devtools/gn/gn_git.bb
> +++ b/meta/recipes-devtools/gn/gn_git.bb
> @@ -49,4 +49,4 @@ BBCLASSEXTEND = "native"
>
>  COMPATIBLE_HOST = "^(?!riscv32).*"
>
> -CFLAGS:append:toolchain-gcc = " -Wno-error=maybe-uninitialized"
> +CFLAGS += "-Wno-error=maybe-uninitialized"

This is not a valid option with clang, I can see the error in report
is seen with gcc ( cc1plus being called there )
Why is it choosing gcc to compile when you selected clang as your
default compiler ?
. I wonder why it is not getting applied when toolchain-gcc OVERRIDE
is applied ?

> --
> 2.39.5
>
>
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>

Re: [OE-core] [PATCH v2] gn: remove gcc override

[Khem Raj]

On Sun, Oct 5, 2025 at 10:06 PM Khem Raj <raj.khem@gmail.com> wrote:
>
> On Sat, Oct 4, 2025 at 9:00 AM Jon Mason via lists.openembedded.org
> <jdmason=kudzu.us@lists.openembedded.org> wrote:
> >
> > When compiling gn with clang, the following errors are being seen (with
> > qemuarm64-secureboot machine, possibly others):
> >
> > In file included from /usr/include/c++/12/string:40,
> >                  from ../sources/gn-0+git/src/base/strings/string_number_conversions.h:11,
> >                  from ../sources/gn-0+git/src/gn/operators.cc:10:
> > In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
> >     inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
> >     inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:202:17:
> > /usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
> >   354 |         __c1 = __c2;
> >       |                ^~~~
> > ../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
> > ../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
> >   198 |   std::string empty_def;
> >       |               ^~~~~~~~~
> > In static member function ‘static constexpr void std::char_traits<char>::assign(char_type&, const char_type&)’,
> >     inlined from ‘static constexpr void std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_S_copy(_CharT*, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:421:23,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Allocator>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::_M_replace(size_type, size_type, const _CharT*, size_type) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.tcc:532:22,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::assign(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:1647:19,
> >     inlined from ‘constexpr std::__cxx11::basic_string<_CharT, _Traits, _Alloc>& std::__cxx11::basic_string<_CharT, _Traits, _Alloc>::operator=(const _CharT*) [with _CharT = char; _Traits = std::char_traits<char>; _Alloc = std::allocator<char>]’ at /usr/include/c++/12/bits/basic_string.h:815:28,
> >     inlined from ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’ at ../sources/gn-0+git/src/gn/operators.cc:205:17:
> > /usr/include/c++/12/bits/char_traits.h:354:16: error: ‘((const std::char_traits<char>::char_type*)((char*)&empty_def + offsetof(std::__cxx11::string, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::<unnamed>)))[2]’ may be used uninitialized [-Werror=maybe-uninitialized]
> >   354 |         __c1 = __c2;
> >       |                ^~~~
> > ../sources/gn-0+git/src/gn/operators.cc: In function ‘Err {anonymous}::MakeOverwriteError(const BinaryOpNode*, const Value&)’:
> > ../sources/gn-0+git/src/gn/operators.cc:198:15: note: ‘empty_def’ declared here
> >   198 |   std::string empty_def;
> >       |               ^~~~~~~~~
> > cc1plus: all warnings being treated as errors
> >
> > Remove the toolchain-gcc override to allow the cflag
> > -Wno-error=maybe-uninitialized to be applied.
> >
> > Signed-off-by: Jon Mason <jon.mason@arm.com>
> > ---
> >  meta/recipes-devtools/gn/gn_git.bb | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/meta/recipes-devtools/gn/gn_git.bb b/meta/recipes-devtools/gn/gn_git.bb
> > index d8896609b193..87ccfe370456 100644
> > --- a/meta/recipes-devtools/gn/gn_git.bb
> > +++ b/meta/recipes-devtools/gn/gn_git.bb
> > @@ -49,4 +49,4 @@ BBCLASSEXTEND = "native"
> >
> >  COMPATIBLE_HOST = "^(?!riscv32).*"
> >
> > -CFLAGS:append:toolchain-gcc = " -Wno-error=maybe-uninitialized"
> > +CFLAGS += "-Wno-error=maybe-uninitialized"
>
> This is not a valid option with clang, I can see the error in report
> is seen with gcc ( cc1plus being called there )
> Why is it choosing gcc to compile when you selected clang as your
> default compiler ?
> . I wonder why it is not getting applied when toolchain-gcc OVERRIDE
> is applied ?

So I guess you are seeing it with gc-native ?
in that case your patch should not only add this warning but also
remove it when toolchain is clang
add

CFLAGS:remove:toolchain-clang = "-Wno-error=maybe-uninitialized"

as well. so it works with clang and gcc both
>
> > --
> > 2.39.5
> >
> >
> > -=-=-=-=-=-=-=-=-=-=-=-
> > Links: You receive all messages sent to this group.
> > View/Reply Online (#224432): https://lists.openembedded.org/g/openembedded-core/message/224432
> > Mute This Topic: https://lists.openembedded.org/mt/115588441/1997914
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> > Unsubscribe: https://lists.openembedded.org/g/openembedded-core/unsub [raj.khem@gmail.com]
> > -=-=-=-=-=-=-=-=-=-=-=-
> >