[PATCH v2] docs: Integrate rustdoc into Rust documentation

[Carlos Bilbao]

Include HTML output generated with rustdoc into the Linux kernel
documentation on Rust. Change target `make htmldocs` to combine RST Sphinx
and the generation of Rust documentation, when support is available.

Signed-off-by: Carlos Bilbao <carlos.bilbao@xxxxxxx>
---

Changes since V1:
 - Work on top of v6.1-rc1.
 - Don't use rustdoc.rst, instead add link to Documentation/rust/index.rst.
 - In Documentation/Makefile, replace @make rustdoc for $(Q)$(MAKE) rustdoc.
 - Don't do LLVM=1 for all rustdoc generation within `make htmldocs`.
 - Add spaces on definition of RUSTDOC_OUTPUT, for consistency.

---
 Documentation/Makefile       |  4 ++++
 Documentation/rust/index.rst |  3 +++
 rust/Makefile                | 15 +++++++++------
 3 files changed, 16 insertions(+), 6 deletions(-)

diff --git a/Documentation/Makefile b/Documentation/Makefile
index 64d44c1ecad3..f537cf558af6 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -92,6 +92,10 @@ quiet_cmd_sphinx = SPHINX  $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
 	fi
 
 htmldocs:
+# If Rust support is available, add rustdoc generated contents
+ifdef CONFIG_RUST
+	$(Q)$(MAKE) rustdoc
+endif
 	@$(srctree)/scripts/sphinx-pre-install --version-check
 	@+$(foreach var,$(SPHINXDIRS),$(call loop_cmd,sphinx,html,$(var),,$(var)))
 
diff --git a/Documentation/rust/index.rst b/Documentation/rust/index.rst
index 4ae8c66b94fa..4005326c3ba9 100644
--- a/Documentation/rust/index.rst
+++ b/Documentation/rust/index.rst
@@ -6,6 +6,9 @@ Rust
 Documentation related to Rust within the kernel. To start using Rust
 in the kernel, please read the quick-start.rst guide.
 
+If this documentation includes rustdoc-generated HTML, the entry point can
+be found `here. <rustdoc/kernel/index.html>`_
+
 .. toctree::
     :maxdepth: 1
 
diff --git a/rust/Makefile b/rust/Makefile
index 7700d3853404..080c07048065 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -1,5 +1,8 @@
 # SPDX-License-Identifier: GPL-2.0
 
+# Where to place rustdoc generated documentation
+RUSTDOC_OUTPUT = $(objtree)/Documentation/output/rust/rustdoc
+
 always-$(CONFIG_RUST) += target.json
 no-clean-files += target.json
 
@@ -58,7 +61,7 @@ quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \
 		$(rustc_target_flags) -L$(objtree)/$(obj) \
-		--output $(objtree)/$(obj)/doc \
+		--output $(RUSTDOC_OUTPUT) \
 		--crate-name $(subst rustdoc-,,$@) \
 		@$(objtree)/include/generated/rustc_cfg $<
 
@@ -75,15 +78,15 @@ quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
 # and then retouch the generated files.
 rustdoc: rustdoc-core rustdoc-macros rustdoc-compiler_builtins \
     rustdoc-alloc rustdoc-kernel
-	$(Q)cp $(srctree)/Documentation/images/logo.svg $(objtree)/$(obj)/doc
-	$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(objtree)/$(obj)/doc
-	$(Q)find $(objtree)/$(obj)/doc -name '*.html' -type f -print0 | xargs -0 sed -Ei \
+	$(Q)cp $(srctree)/Documentation/images/logo.svg $(RUSTDOC_OUTPUT)
+	$(Q)cp $(srctree)/Documentation/images/COPYING-logo $(RUSTDOC_OUTPUT)
+	$(Q)find $(RUSTDOC_OUTPUT) -name '*.html' -type f -print0 | xargs -0 sed -Ei \
 		-e 's:rust-logo\.svg:logo.svg:g' \
 		-e 's:rust-logo\.png:logo.svg:g' \
 		-e 's:favicon\.svg:logo.svg:g' \
 		-e 's:<link rel="alternate icon" type="image/png" href="[./]*favicon-(16x16|32x32)\.png">::g'
 	$(Q)echo '.logo-container > img { object-fit: contain; }' \
-		>> $(objtree)/$(obj)/doc/rustdoc.css
+		>> $(RUSTDOC_OUTPUT)/rustdoc.css
 
 rustdoc-macros: private rustdoc_host = yes
 rustdoc-macros: private rustc_target_flags = --crate-type proc-macro \
@@ -141,7 +144,7 @@ quiet_cmd_rustdoc_test = RUSTDOC T $<
 		@$(objtree)/include/generated/rustc_cfg \
 		$(rustc_target_flags) $(rustdoc_test_target_flags) \
 		--sysroot $(objtree)/$(obj)/test/sysroot $(rustdoc_test_quiet) \
-		-L$(objtree)/$(obj)/test --output $(objtree)/$(obj)/doc \
+		-L$(objtree)/$(obj)/test --output $(RUSTDOC_OUTPUT) \
 		--crate-name $(subst rusttest-,,$@) $<
 
 # We cannot use `-Zpanic-abort-tests` because some tests are dynamic,

base-commit: 9abf2313adc1ca1b6180c508c25f22f9395cc780
-- 
2.34.1