[PATCH] sanity.bbclass: warn on .cargo/config.toml outside the build tree

[PATCH] sanity.bbclass: warn on .cargo/config.toml outside the build tree

[Hemanth.KumarMD]

From: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>

Cargo walks from CWD up to the filesystem root merging every
.cargo/config.toml it finds. Any such file above TOPDIR is silently
picked up and can override Yocto's linker, registry or compiler
settings, leading to build failures.

Until cargo provides a proper fix upstream, add a warning so users
get a clear diagnostic instead of a build error.

Upstream meta-issue: https://github.com/rust-lang/cargo/issues/9769

[YOCTO #15637]

Signed-off-by: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>
---
 meta/classes-global/sanity.bbclass | 33 ++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/meta/classes-global/sanity.bbclass b/meta/classes-global/sanity.bbclass
index bdfa7f059d..c67c7b8f03 100644
--- a/meta/classes-global/sanity.bbclass
+++ b/meta/classes-global/sanity.bbclass
@@ -854,6 +854,38 @@ def sanity_check_locale(d):
     except locale.Error:
         raise_sanity_error("Your system needs to support the en_US.UTF-8 locale.", d)
 
+def check_cargo_config(d):
+    # Cargo merges .cargo/config.toml from every directory between CWD and
+    # the filesystem root. Warn for anything found in ancestor directories
+    # above TOPDIR that Cargo would pick up silently.
+    import os
+
+    topdir = d.getVar('TOPDIR')
+    ancestor = os.path.dirname(topdir)
+    found = []
+    last_ancestor = None
+    while True:
+        for name in ('config.toml', 'config'):
+            cfg = os.path.join(ancestor, '.cargo', name)
+            if os.path.exists(cfg):
+                found.append(cfg)
+                last_ancestor = ancestor
+                break
+        parent = os.path.dirname(ancestor)
+        if parent == ancestor:
+            break
+        ancestor = parent
+
+    if found:
+        bb.warn("Cargo config file(s) found at %s which is/are outside the build "
+                "directory. Cargo will silently apply their settings during the "
+                "rust/cargo build and can override Yocto's settings like linker, "
+                "registry or compiler settings causing build failures. You can "
+                "either remove these file(s) or move your build directory outside "
+                "of %s to fix this. "
+                "See https://bugzilla.yoctoproject.org/show_bug.cgi?id=15637 for more details."
+                % (', '.join(found), last_ancestor))
+
 def check_sanity_everybuild(status, d):
     import os, stat
     # Sanity tests which test the users environment so need to run at each build (or are so cheap
@@ -873,6 +905,7 @@ def check_sanity_everybuild(status, d):
         status.addresult('Bitbake version %s is required and version %s was found\n' % (minversion, bb.__version__))
 
     sanity_check_locale(d)
+    check_cargo_config(d)
 
     paths = d.getVar('PATH').split(":")
     if "." in paths or "./" in paths or "" in paths:
-- 
2.49.0

Re: [OE-core] [PATCH] sanity.bbclass: warn on .cargo/config.toml outside the build tree

[Paul Barker]

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On Tue, 2026-06-23 at 23:42 -0700, Hemanth Kumar M D via
lists.openembedded.org wrote:
> From: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>
> 
> Cargo walks from CWD up to the filesystem root merging every
> .cargo/config.toml it finds. Any such file above TOPDIR is silently
> picked up and can override Yocto's linker, registry or compiler
> settings, leading to build failures.
> 
> Until cargo provides a proper fix upstream, add a warning so users
> get a clear diagnostic instead of a build error.
> 
> Upstream meta-issue: https://github.com/rust-lang/cargo/issues/9769
> 
> [YOCTO #15637]
> 
> Signed-off-by: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>
> ---
>  meta/classes-global/sanity.bbclass | 33 ++++++++++++++++++++++++++++++
>  1 file changed, 33 insertions(+)
> 
> diff --git a/meta/classes-global/sanity.bbclass b/meta/classes-global/sanity.bbclass
> index bdfa7f059d..c67c7b8f03 100644
> --- a/meta/classes-global/sanity.bbclass
> +++ b/meta/classes-global/sanity.bbclass
> @@ -854,6 +854,38 @@ def sanity_check_locale(d):
>      except locale.Error:
>          raise_sanity_error("Your system needs to support the en_US.UTF-8 locale.", d)
>  
> +def check_cargo_config(d):
> +    # Cargo merges .cargo/config.toml from every directory between CWD and
> +    # the filesystem root. Warn for anything found in ancestor directories
> +    # above TOPDIR that Cargo would pick up silently.
> +    import os
> +
> +    topdir = d.getVar('TOPDIR')

TMPDIR and each package's WORKDIR are under TOPDIR by default, but this
can be overridden. Perhaps we should be checking ancestors of
BASE_WORKDIR instead.

> +    ancestor = os.path.dirname(topdir)
> +    found = []
> +    last_ancestor = None
> +    while True:
> +        for name in ('config.toml', 'config'):
> +            cfg = os.path.join(ancestor, '.cargo', name)
> +            if os.path.exists(cfg):
> +                found.append(cfg)
> +                last_ancestor = ancestor
> +                break

This `break` should be dropped so that we tell the user about all
offending Cargo config files.

The rest of this patch LGTM, thanks!

Best regards,

-- 
Paul Barker


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Re: [OE-core] [PATCH] sanity.bbclass: warn on .cargo/config.toml outside the build tree

[Hemanth Kumar M D]

On 24-06-2026 01:11 pm, Paul Barker wrote:
> On Tue, 2026-06-23 at 23:42 -0700, Hemanth Kumar M D via
> lists.openembedded.org wrote:
>> From: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>
>>
>> Cargo walks from CWD up to the filesystem root merging every
>> .cargo/config.toml it finds. Any such file above TOPDIR is silently
>> picked up and can override Yocto's linker, registry or compiler
>> settings, leading to build failures.
>>
>> Until cargo provides a proper fix upstream, add a warning so users
>> get a clear diagnostic instead of a build error.
>>
>> Upstream meta-issue: https://github.com/rust-lang/cargo/issues/9769
>>
>> [YOCTO #15637]
>>
>> Signed-off-by: Hemanth Kumar M D <Hemanth.KumarMD@windriver.com>
>> ---
>>   meta/classes-global/sanity.bbclass | 33 ++++++++++++++++++++++++++++++
>>   1 file changed, 33 insertions(+)
>>
>> diff --git a/meta/classes-global/sanity.bbclass b/meta/classes-global/sanity.bbclass
>> index bdfa7f059d..c67c7b8f03 100644
>> --- a/meta/classes-global/sanity.bbclass
>> +++ b/meta/classes-global/sanity.bbclass
>> @@ -854,6 +854,38 @@ def sanity_check_locale(d):
>>       except locale.Error:
>>           raise_sanity_error("Your system needs to support the en_US.UTF-8 locale.", d)
>>   
>> +def check_cargo_config(d):
>> +    # Cargo merges .cargo/config.toml from every directory between CWD and
>> +    # the filesystem root. Warn for anything found in ancestor directories
>> +    # above TOPDIR that Cargo would pick up silently.
>> +    import os
>> +
>> +    topdir = d.getVar('TOPDIR')

Hi Paul,

Thanks for the review!

please find the v2 - 
https://lists.openembedded.org/g/openembedded-core/topic/patch_v2_sanity_bbclass/119970000 

> TMPDIR and each package's WORKDIR are under TOPDIR by default, but this
> can be overridden. Perhaps we should be checking ancestors of
> BASE_WORKDIR instead.
Agreed, updated to use BASE_WORKDIR in v2.
>> +    ancestor = os.path.dirname(topdir)
>> +    found = []
>> +    last_ancestor = None
>> +    while True:
>> +        for name in ('config.toml', 'config'):
>> +            cfg = os.path.join(ancestor, '.cargo', name)
>> +            if os.path.exists(cfg):
>> +                found.append(cfg)
>> +                last_ancestor = ancestor
>> +                break
> This `break` should be dropped so that we tell the user about all
> offending Cargo config files.
Keeping the `break` ,
   Cargo docs say if both 'config' and 'config.toml'
   exist in the same directory, only 'config' is read. So only one file per
   directory is ever active. I've also fixed the probe order to check 
'config'
   before 'config.toml' to match this.
   Ref: https://doc.rust-lang.org/cargo/reference/config.html
> The rest of this patch LGTM, thanks!
>
> Best regards,
>
-- 
Regards,
Hemanth Kumar M D