Re: [Buildroot] [PATCH] package/go: ensure the toolchain is available

["Yann E. MORIN" <yann.morin.1998@free.fr>]

All,

On 2024-06-20 20:21 +0200, Yann E. MORIN spake thusly:
> The toolchain is needed to build the final-stage go compiler, when it
> should have CGO support.
> 
> However, in commit 0290c543dec8 (package/go: new subdirectory for go
> variants), the HOST_GO_DEPENDENCIES assignment was only partially split
> off to the new location; part of it was left in the ole go.mk to act as
> common variables. With that commit, the go package had not been renamed,
> which meant that the dependencies were still correct.
> 
> But in commit fa2536ec9401 (package/go: make host package a virtual
> package), the 'go' package was renamed to 'go-src', and replaced by a
> 'go' virtual package.
> 
> The variables in the go-src package were properly renamed, and the
> variables in the go virtual package were properly _not_ renamed. As a
> consequence, the go-src package lost its dependency on the toolchain
> when needed, while the go virtual package still had it.
> 
> However, that was not correct when CGO is enabled (i.e. when the target
> has threads): go-src then fails to build:
> 
>     Building Go cmd/dist using [...]/host/lib/go-1.21.8. (go1.21.8 linux/amd64)
>     go tool dist: cannot invoke C compiler ["[...]/host/bin/aarch64-linux-gcc"]:
>     fork/exec [...]/host/bin/aarch64-linux-gcc: no such file or directory
> 
>     Go needs a system C compiler for use with cgo.
>     To set a C compiler, set CC=the-compiler.
>     To disable cgo, set CGO_ENABLED=0.
> 
> After some retro-thinking, the reasoning behind this was that the
> toolchain would _also_ be needed when using the prebuilt go-bin, which
> is indeed correct, so by having it as a dependency of the virtual
> package, it would ensure the toolchain be present in both cases, when
> building from scratch or when using a prebuilt go.
> 
> The oversight being that the toolchain is _also_ needed to actually
> build go when CGO is enabled.
> 
> We fix this by handling the toolchain dependency for CGO by exposing it
> in a variable, that can be used as a dependency in go-src, like is done
> to actually enable or disable CGO support.
> 
> We still ensure that host-go still depends on it, for a future go-bin
> provider.
> 
> Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

Applied to master, thanks.

Regards,
Yann E. MORIN.

> ---
>  package/go/go-src/go-src.mk | 4 +++-
>  package/go/go.mk            | 5 ++++-
>  2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/package/go/go-src/go-src.mk b/package/go/go-src/go-src.mk
> index 1e061e20bc..0d1a9b3187 100644
> --- a/package/go/go-src/go-src.mk
> +++ b/package/go/go-src/go-src.mk
> @@ -12,7 +12,9 @@ GO_SRC_LICENSE_FILES = LICENSE
>  GO_SRC_CPE_ID_VENDOR = golang
>  
>  HOST_GO_SRC_PROVIDES = host-go
> -HOST_GO_SRC_DEPENDENCIES = host-go-bootstrap-stage3
> +HOST_GO_SRC_DEPENDENCIES = \
> +	host-go-bootstrap-stage3 \
> +	$(HOST_GO_DEPENDENCIES_CGO)
>  
>  ifeq ($(BR2_PACKAGE_HOST_GO_TARGET_ARCH_SUPPORTS),y)
>  
> diff --git a/package/go/go.mk b/package/go/go.mk
> index 6f92893204..91a8fb828f 100644
> --- a/package/go/go.mk
> +++ b/package/go/go.mk
> @@ -83,7 +83,7 @@ HOST_GO_TARGET_ENV = \
>  # any target package needing cgo support must include
>  # 'depends on BR2_TOOLCHAIN_HAS_THREADS' in its config file.
>  ifeq ($(BR2_TOOLCHAIN_HAS_THREADS),y)
> -HOST_GO_DEPENDENCIES += toolchain
> +HOST_GO_DEPENDENCIES_CGO += toolchain
>  HOST_GO_CGO_ENABLED = 1
>  else
>  HOST_GO_CGO_ENABLED = 0
> @@ -95,6 +95,9 @@ else # !BR2_PACKAGE_HOST_GO_TARGET_ARCH_SUPPORTS
>  HOST_GO_CGO_ENABLED = 1
>  endif # BR2_PACKAGE_HOST_GO_TARGET_ARCH_SUPPORTS
>  
> +# Ensure the toolchain is available, whatever the provider
> +HOST_GO_DEPENDENCIES += $(HOST_GO_DEPENDENCIES_CGO)
> +
>  # For the convenience of host golang packages
>  HOST_GO_HOST_ENV = \
>  	$(HOST_GO_COMMON_ENV) \
> -- 
> 2.45.1
> 
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