[PATCH v2 1/2] Makefile: rust-analyzer target: better error handling

[John Hubbard <jhubbard@nvidia.com>]

1) Provide a better error message for the "Rust not available" case.
Without this patch, one gets various misleading messages, such as:

    "No rule to make target 'rust-analyzer'"

Instead, run scripts/rust_is_available.sh directly, as a prerequisite,
and let that script report the cause of any problems, as well as
providing a link to the documentation. Thanks to Miguel Ojeda for the
idea of just letting rust_is_available.sh report its results directly.

The new output in the failure case looks like this:

$ make rust-analyzer
***
*** Rust compiler 'rustc' could not be found.
***
***
*** Please see Documentation/rust/quick-start.rst for details
*** on how to set up the Rust support.
***
make[1]: *** [/kernel_work/linux-github/Makefile:1975: rust-analyzer] Error 1
make: *** [Makefile:240: __sub-make] Error 2

Cc: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/Makefile b/Makefile
index 14427547dc1e..07308277a6f5 100644
--- a/Makefile
+++ b/Makefile
@@ -1970,6 +1970,7 @@ tags TAGS cscope gtags: FORCE
 # IDE support targets
 PHONY += rust-analyzer
 rust-analyzer:
+	$(Q)$(CONFIG_SHELL) $(srctree)/scripts/rust_is_available.sh
 	$(Q)$(MAKE) $(build)=rust $@
 
 # Script to generate missing namespace dependencies
-- 
2.45.2