Re: [PATCH] Makefile: pin cargo --target-dir to ./target

[Junio C Hamano <gitster@pobox.com>]

Andy Koppe <andy.koppe@gmail.com> writes:

> The Makefile assumes that cargo places build artifacts under ./target.
> That assumption breaks if the user has a custom target dir setting, e.g.
> in their ~/.cargo/config.toml file or in the CARGO_TARGET_DIR env var.
> This results in a link error due to failing to find the gitcore library
> built with cargo.
>
> To fix this, pass '--target-dir target' to the cargo commands that build
> gitcore. Add it directly to the recipes rather than to CARGO_ARGS, so
> that it isn't lost if CARGO_ARGS is overridden.
>
> Leave the contrib/libgit-{sys,rs} targets alone, as nothing depends on
> the location of their build output.
>
> The Meson build of gitcore already passes --target-dir explicitly.
>
> Signed-off-by: Andy Koppe <andy.koppe@gmail.com>
> ---
>  Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

The change might make sense, but these areas are touched by other
topics in flight.

Given that they both appear on the same line as $(CARGO_ARGS)
appears, I have to wonder if we want to instead just add a single

    CARGO_ARGS += --target-dir target

somewhere early that are unreleated to these individual rules?

> diff --git a/Makefile b/Makefile
> index c649c93c51..aea99a3639 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -3039,7 +3039,7 @@ $(LIB_FILE): $(LIB_OBJS)
>  ifndef NO_RUST
>  ifeq ($(RUST_TARGETS),)
>  $(RUST_LIB): Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
> -	$(QUIET_CARGO)cargo build $(CARGO_ARGS)
> +	$(QUIET_CARGO)cargo build $(CARGO_ARGS) --target-dir target
>  else
>  ifneq ($(words $(RUST_TARGETS)),1)
>  ifneq ($(uname_S),Darwin)
> @@ -3049,7 +3049,7 @@ endif
>  
>  RUST_MEMBER_LIBS = $(foreach target,$(RUST_TARGETS),target/$(target)/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME))
>  $(RUST_MEMBER_LIBS): target/%/$(RUST_BUILD_CONFIG)/$(RUST_LIB_NAME): Cargo.toml $(RUST_SOURCES) $(LIB_FILE)
> -	$(QUIET_CARGO)cargo build $(CARGO_ARGS) --target $*
> +	$(QUIET_CARGO)cargo build $(CARGO_ARGS) --target-dir target --target $*
>  
>  $(RUST_LIB): $(RUST_MEMBER_LIBS)
>  	$(call mkdir_p_parent_template)