rust: use the hidden variant of rust-project.json

Very soon after we requested it [1], `rust-analyzer` added support for
`.rust-project.json` [2], i.e. the hidden variant of `.rust-project.json`.

While this is only a (tiny) issue for kernel developers that use Rust
(i.e. so far a very small number compared to the total), the file is not
really something most kernel developers need to see, care or modify while
working, so it is not really needed to show it by default in listings.

It also follows the pattern of other files that are not directly related
to the project (unlike e.g. a `Kconfig` file).

Thus migrate to it.

Cc: Ali Bektas <bektasali@protonmail.com>
Cc: Lukas Wirth <lukastw97@gmail.com>
Link: rust-lang/rust-analyzer#17816 [1]
Link: rust-lang/rust-analyzer#17818 [2]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

.gitignore

@@ -176,4 +176,4 @@ x509.genkey
 sphinx_*/
 
 # Rust analyzer configuration
-/rust-project.json
+/.rust-project.json

Documentation/rust/quick-start.rst

@@ -259,7 +259,7 @@ The `rust-analyzer <https://rust-analyzer.github.io/>`_ language server can
 be used with many editors to enable syntax highlighting, completion, go to
 definition, and other features.
 
-``rust-analyzer`` needs a configuration file, ``rust-project.json``, which
+``rust-analyzer`` needs a configuration file, ``.rust-project.json``, which
 can be generated by the ``rust-analyzer`` Make target::
 
 	make LLVM=1 rust-analyzer

Makefile

@@ -1483,7 +1483,7 @@ endif # CONFIG_MODULES
 CLEAN_FILES += vmlinux.symvers modules-only.symvers \
 	       modules.builtin modules.builtin.modinfo modules.nsdeps \
 	       compile_commands.json rust/test \
-	       rust-project.json .vmlinux.objs .vmlinux.export.c
+	       .rust-project.json .vmlinux.objs .vmlinux.export.c
 
 # Directories & files removed with 'make mrproper'
 MRPROPER_FILES += include/config include/generated          \
@@ -1621,7 +1621,7 @@ help:
 	@echo  '		    (requires kernel .config)'
 	@echo  '  rusttest        - Runs the Rust tests'
 	@echo  '                    (requires kernel .config; downloads external repos)'
-	@echo  '  rust-analyzer	  - Generate rust-project.json rust-analyzer support file'
+	@echo  '  rust-analyzer	  - Generate .rust-project.json rust-analyzer support file'
 	@echo  '		    (requires kernel .config)'
 	@echo  '  dir/file.[os]   - Build specified target only'
 	@echo  '  dir/file.rsi    - Build macro expanded source, similar to C preprocessing.'
@@ -1809,7 +1809,7 @@ help:
 	@echo  '  modules         - default target, build the module(s)'
 	@echo  '  modules_install - install the module'
 	@echo  '  clean           - remove generated files in module directory only'
-	@echo  '  rust-analyzer	  - generate rust-project.json rust-analyzer support file'
+	@echo  '  rust-analyzer	  - generate .rust-project.json rust-analyzer support file'
 	@echo  ''
 
 ifndef CONFIG_MODULES
@@ -1958,7 +1958,7 @@ quiet_cmd_tags = GEN     $@
 tags TAGS cscope gtags: FORCE
 	$(call cmd,tags)
 
-# Generate rust-project.json (a file that describes the structure of non-Cargo
+# Generate .rust-project.json (a file that describes the structure of non-Cargo
 # Rust projects) for rust-analyzer (an implementation of the Language Server
 # Protocol).
 PHONY += rust-analyzer

rust/Makefile

@@ -351,7 +351,7 @@ rust-analyzer:
 		--cfgs='core=$(core-cfgs)' --cfgs='alloc=$(alloc-cfgs)' \
 		$(realpath $(srctree)) $(realpath $(objtree)) \
 		$(RUST_LIB_SRC) $(KBUILD_EXTMOD) > \
-		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/rust-project.json
+		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/.rust-project.json
 
 redirect-intrinsics = \
 	__addsf3 __eqsf2 __gesf2 __lesf2 __ltsf2 __mulsf3 __nesf2 __unordsf2 \

scripts/generate_rust_analyzer.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 # SPDX-License-Identifier: GPL-2.0
-"""generate_rust_analyzer - Generates the `rust-project.json` file for `rust-analyzer`.
+"""generate_rust_analyzer - Generates the `.rust-project.json` file for `rust-analyzer`.
 """
 
 import argparse

scripts/remove-stale-files

@@ -21,3 +21,5 @@ set -e
 # then will be really dead and removed from the code base entirely.
 
 rm -f *.spec
+
+rm -f rust-project.json