Re: [oe-core][PATCH 1/2] clang: fix IsOpenEmbedded() detection for CLANG_EXTRA_OE_DISTRO entries

Re: [oe-core][PATCH 1/2] clang: fix IsOpenEmbedded() detection for CLANG_EXTRA_OE_DISTRO entries

[Markus Volk]

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Since being 'self-contained' is something I care about, I've been 
bothered for years by an issue where, using a self-built Yocto image 
with a built-in build appliance, I hit a failure in libcxx-native as 
soon as TOOLCHAIN = "clang" is used. With the help of claude.ai and a 
lot of debugging, I put together this patch, which fixes my problem.

On Wed, Aug 12 2026 at 18:13:40 +02:00:00, Markus Volk via 
lists.openembedded.org <f_l_k=t-online.de@lists.openembedded.org> wrote:
> do_preconfigure builds Distro::IsOpenEmbedded() from 
> CLANG_EXTRA_OE_DISTRO,
> but two bugs silently defeat OE-host detection for any distro beyond
> the shipped default (poky:poky).
> 
> The check is assembled by appending each entry as 'NAME ||' and
> stripping the trailing operator, so only the first entry gets a
> 'DistroVal ==' prefix.
> With more than one entry this generates e.g.:
>  bool IsOpenEmbedded() const { return DistroVal == POKY 
> ||WAYLAND_DESKTOP; }
> and compiles but IsOpenEmbedded() then always returns true regardless 
> of the
> actual distro, since a non-zero enumerator is truthy -- the check 
> becomes
> disabled rather than extended.
> 
> Separately, the .Case() match string is built from the
> underscore-converted identifier (needed since it doubles as a C++
> enumerator name) instead of the raw distro id as it appears in
> /etc/os-release. Since detection compares directly against the raw
> ID= value, any distro name containing a hyphen never matches.
> 
> This only surfaces on a self-hosted OE build host (e.g. via
> packagegroup-core-buildessential/-core-sdk) with a non-'poky' DISTRO
> registered in CLANG_EXTRA_OE_DISTRO. Mainstream distros never hit
> this path, since their native GCC keeps crt objects and headers
> together in one directory that clang's default search already finds.
> OE-built hosts split these across two directories, which is exactly
> what the IsOpenEmbedded()-gated candidate exists to handle -- with it
> disabled, native clang-toolchain builds (e.g. libcxx-native) fail:
> 
>     /usr/bin/x86_64-oe-linux-ld: cannot find crtbeginS.o: No such 
> file or directory
>     /usr/bin/x86_64-oe-linux-ld: cannot find -lgcc: No such file or 
> directory
> 
> Verified with debug instrumentation in
> GCCInstallationDetector::ScanLibDirForGCCTriple(): with both fixes
> applied, clang -v correctly reports:
> 
>     Found candidate GCC installation: /usr/lib/x86_64-oe-linux/16.1.0
>     Selected GCC installation: /usr/lib/x86_64-oe-linux/16.1.0
> 
> Build each comparison explicitly and join with ' || ', and use the
> raw (hyphenated) distro id for the .Case() match while keeping the
> underscore-converted identifier only for the generated C++
> enumerator/method names.
> 
> Signed-off-by: Markus Volk <f_l_k@t-online.de 
> <mailto:f_l_k@t-online.de>>
> Co-authored-by: Claude <noreply@anthropic.com 
> <mailto:noreply@anthropic.com>>
> ---
>  meta/recipes-devtools/clang/llvm-project-source.inc | 11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> diff --git a/meta/recipes-devtools/clang/llvm-project-source.inc 
> b/meta/recipes-devtools/clang/llvm-project-source.inc
> index 85b5ef06dc..5cd08d4085 100644
> --- a/meta/recipes-devtools/clang/llvm-project-source.inc
> +++ b/meta/recipes-devtools/clang/llvm-project-source.inc
> @@ -65,18 +65,19 @@ python do_preconfigure() {
>      triple = ""
>      name = ""
>      check = ""
> -    oe_names = ""
> +    oe_names = []
>      distros = d.getVar('CLANG_EXTRA_OE_DISTRO')
>      for distro in distros.split():
> -        distro_id = distro.split(":")[0].replace('-','_')
> +        distro_id_raw = distro.split(":")[0]
> +        distro_id = distro_id_raw.replace('-','_')
>          distro_triple = distro.split(":")[1]
> -        case += '\\n    .Case("' + distro_id + '", Distro::' + 
> distro_id.upper() + ')'
> +        case += '\\n    .Case("' + distro_id_raw + '", Distro::' + 
> distro_id.upper() + ')'
>          triple += '\\n   if (Distro.Is' + distro_id.upper() + 
> '())\\n     return "x86_64-' + distro_triple + '-linux";'
>          name += '\\n    '+ distro_id.upper() + ','
>          check += '\\nbool Is' + distro_id.upper() + '() const { 
> return DistroVal == ' + distro_id.upper() + '; }'
> -        oe_names +=  distro_id.upper() + ' ||'
> +        oe_names.append('DistroVal == ' + distro_id.upper())
> 
> -    check += '\\nbool IsOpenEmbedded() const { return DistroVal == ' 
> + oe_names[0:-3] + '; }'
> +    check += '\\nbool IsOpenEmbedded() const { return ' + ' || 
> '.join(oe_names) + '; }'
> 
>      cmd = ['sed', '-i', 's#//CLANG_EXTRA_OE_DISTRO_NAME#%s#g' % 
> name, source + '/clang/include/clang/Driver/Distro.h']
>      subprocess.check_output(cmd, stderr=subprocess.STDOUT)
> --
> 2.55.0
> 
> 
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[oe-core][PATCH 1/2] clang: fix IsOpenEmbedded() detection for CLANG_EXTRA_OE_DISTRO entries

[Markus Volk]

do_preconfigure builds Distro::IsOpenEmbedded() from CLANG_EXTRA_OE_DISTRO,
but two bugs silently defeat OE-host detection for any distro beyond
the shipped default (poky:poky).

The check is assembled by appending each entry as 'NAME ||' and
stripping the trailing operator, so only the first entry gets a
'DistroVal ==' prefix.
With more than one entry this generates e.g.:
 bool IsOpenEmbedded() const { return DistroVal == POKY ||WAYLAND_DESKTOP; }
and compiles but IsOpenEmbedded() then always returns true regardless of the
actual distro, since a non-zero enumerator is truthy -- the check becomes
disabled rather than extended.

Separately, the .Case() match string is built from the
underscore-converted identifier (needed since it doubles as a C++
enumerator name) instead of the raw distro id as it appears in
/etc/os-release. Since detection compares directly against the raw
ID= value, any distro name containing a hyphen never matches.

This only surfaces on a self-hosted OE build host (e.g. via
packagegroup-core-buildessential/-core-sdk) with a non-'poky' DISTRO
registered in CLANG_EXTRA_OE_DISTRO. Mainstream distros never hit
this path, since their native GCC keeps crt objects and headers
together in one directory that clang's default search already finds.
OE-built hosts split these across two directories, which is exactly
what the IsOpenEmbedded()-gated candidate exists to handle -- with it
disabled, native clang-toolchain builds (e.g. libcxx-native) fail:

    /usr/bin/x86_64-oe-linux-ld: cannot find crtbeginS.o: No such file or directory
    /usr/bin/x86_64-oe-linux-ld: cannot find -lgcc: No such file or directory

Verified with debug instrumentation in
GCCInstallationDetector::ScanLibDirForGCCTriple(): with both fixes
applied, clang -v correctly reports:

    Found candidate GCC installation: /usr/lib/x86_64-oe-linux/16.1.0
    Selected GCC installation: /usr/lib/x86_64-oe-linux/16.1.0

Build each comparison explicitly and join with ' || ', and use the
raw (hyphenated) distro id for the .Case() match while keeping the
underscore-converted identifier only for the generated C++
enumerator/method names.

Signed-off-by: Markus Volk <f_l_k@t-online.de>
Co-authored-by: Claude <noreply@anthropic.com>
---
 meta/recipes-devtools/clang/llvm-project-source.inc | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/meta/recipes-devtools/clang/llvm-project-source.inc b/meta/recipes-devtools/clang/llvm-project-source.inc
index 85b5ef06dc..5cd08d4085 100644
--- a/meta/recipes-devtools/clang/llvm-project-source.inc
+++ b/meta/recipes-devtools/clang/llvm-project-source.inc
@@ -65,18 +65,19 @@ python do_preconfigure() {
     triple = ""
     name = ""
     check = ""
-    oe_names = ""
+    oe_names = []
     distros = d.getVar('CLANG_EXTRA_OE_DISTRO')
     for distro in distros.split():
-        distro_id = distro.split(":")[0].replace('-','_')
+        distro_id_raw = distro.split(":")[0]
+        distro_id = distro_id_raw.replace('-','_')
         distro_triple = distro.split(":")[1]
-        case += '\\n    .Case("' + distro_id + '", Distro::' + distro_id.upper() + ')'
+        case += '\\n    .Case("' + distro_id_raw + '", Distro::' + distro_id.upper() + ')'
         triple += '\\n   if (Distro.Is' + distro_id.upper() + '())\\n     return "x86_64-' + distro_triple + '-linux";'
         name += '\\n    '+ distro_id.upper() + ','
         check += '\\nbool Is' + distro_id.upper() + '() const { return DistroVal == ' + distro_id.upper() + '; }'
-        oe_names +=  distro_id.upper() + ' ||'
+        oe_names.append('DistroVal == ' + distro_id.upper())
 
-    check += '\\nbool IsOpenEmbedded() const { return DistroVal == ' + oe_names[0:-3] + '; }'
+    check += '\\nbool IsOpenEmbedded() const { return ' + ' || '.join(oe_names) + '; }'
 
     cmd = ['sed', '-i', 's#//CLANG_EXTRA_OE_DISTRO_NAME#%s#g' % name, source + '/clang/include/clang/Driver/Distro.h']
     subprocess.check_output(cmd, stderr=subprocess.STDOUT)
-- 
2.55.0