chromium: Depend on libstd-rs instead of rust

Fixes OSSystems#792.

Build and patch changes:
------------------------

In OSSystems#782, we decided to depend on rust instead of libstd-rs, because the
latter didn't include libprofiler_builtins and also used a naming scheme
that trips up Chromium.

However, in OSSystems#791 we decided to patch Chromium so that it doesn't need
libprofiler_builtins any more, because the master version of the rust
recipe also doesn't include it.

Finally, while investigating OSSystems#792 it turned out that our approach breaks
as soon as we have something that depends on libstd-rs in our dependency
graph. In that scenario, both libstd-rs and rust (the latter due to our
bbappend file) install Rust libraries to /usr/lib/rustlib. This first
leads to Chromium build system errors (due to libstd-rs's naming
scheme), and after fixing these to Rust compiler errors due to multiple
versions being present.

The conclusion is now that we can depend on libstd-rs we should do so.
This only requires a small change to Chromium's Rust build scripts to
adapt them to the slightly different naming scheme.

License changes:
----------------

Added licenses: none.

Removed licenses: none.

Updated licenses: none.

Test-built:
-----------

* chromium-wayland:
 - nanbield, clang, MACHINE=qemuarm64

* chromium-x11:
 - master, clang,   MACHINE=qemuarm

Signed-off-by: Max Ihlenfeldt <[email protected]>

meta-chromium/recipes-browser/chromium/chromium-gn.inc

@@ -72,6 +72,7 @@ DEPENDS += " \
     jpeg \
     libdrm \
     libffi \
+    libstd-rs \
     libwebp \
     libxkbcommon \
     libxslt \
@@ -86,7 +87,6 @@ DEPENDS += " \
     pkgconfig-native \
     ${@bb.utils.contains('DISTRO_FEATURES', 'pulseaudio', 'pulseaudio', '', d)} \
     qemu-native \
-    rust \
     rust-native \
     virtual/libgl \
 "

meta-chromium/recipes-browser/chromium/files/0009-Adjust-the-Rust-build-to-our-needs.patch

@@ -19,8 +19,8 @@ Signed-off-by: Max Ihlenfeldt <[email protected]>
  build/config/rust.gni            | 24 +++++++++++++++++------
  build/rust/rustc_wrapper.py      |  1 +
  build/rust/std/BUILD.gn          | 33 ++++++++++++++++++++++++--------
- build/rust/std/find_std_rlibs.py | 13 ++++++++++---
- 4 files changed, 54 insertions(+), 17 deletions(-)
+ build/rust/std/find_std_rlibs.py | 17 +++++++++++-----
+ 4 files changed, 56 insertions(+), 19 deletions(-)
 
 diff --git a/build/config/rust.gni b/build/config/rust.gni
 index e98d913..6213b72 100644
@@ -166,9 +166,18 @@ index 77f4b8c..8a25798 100644
        # The host builds tools toolchain supports Rust only and does not use
        # the allocator remapping to point it to PartitionAlloc.
 diff --git a/build/rust/std/find_std_rlibs.py b/build/rust/std/find_std_rlibs.py
-index 386258f..25fdedc 100755
+index 386258f..3bb6a41 100755
 --- a/build/rust/std/find_std_rlibs.py
 +++ b/build/rust/std/find_std_rlibs.py
+@@ -17,7 +17,7 @@ import re
+ from collections import defaultdict
+
+ EXPECTED_STDLIB_INPUT_REGEX = re.compile(r"([0-9a-z_]+)(?:-([0-9]+))?$")
+-RLIB_NAME_REGEX = re.compile(r"lib([0-9a-z_]+)-([0-9a-f]+)\.rlib$")
++RLIB_NAME_REGEX = re.compile(r"lib([0-9a-z_]+)(-([0-9a-f]+))?\.rlib$")
+
+
+ def main():
 @@ -52,6 +52,8 @@ def main():
      rustc_args.extend(["--target", args.target])
    rustlib_dir = subprocess.check_output(rustc_args).rstrip().decode()
@@ -187,6 +196,15 @@ index 386258f..25fdedc 100755
 
      def copy_file(infile, outfile):
        depfile.write(f" {infile}")
+@@ -99,7 +101,7 @@ def main():
+       # the correct file path to our linker invocations, we don't need
+       # that, and it would prevent us having the predictable filenames
+       # which we need for statically computable gn dependency rules.
+-      (crate_name, metadata) = RLIB_NAME_REGEX.match(f).group(1, 2)
++      (crate_name, metadata) = RLIB_NAME_REGEX.match(f).group(1, 3)
+
+       # Use the number of times we've seen this name to disambiguate the output
+       # filenames. Since we sort the input filenames including the metadata,
 @@ -117,14 +119,19 @@ def main():
        output_filename = f"lib{concise_name}.rlib"
 

meta-chromium/recipes-browser/chromium/libstd-rs_%.bbappend

@@ -0,0 +1,9 @@
+FILES:${PN} += "${libdir}/rustlib/*/target.json"
+
+# Without this, rustc fails with "could not find specification for target ...".
+do_install:append() {
+    target_dir=`realpath "${D}${rustlibdir}"/..`
+    target_triple=`basename "${target_dir}"`
+    target_json="${target_dir}/target.json"
+    RUSTC_BOOTSTRAP=1 rustc -Z unstable-options --print target-spec-json --target "${target_triple}" > "${target_json}"
+}

meta-chromium/recipes-browser/chromium/rust_%.bbappend

@@ -5,22 +5,3 @@
 rust_do_install:append() {
     install -m 0644 ${WORKDIR}/rust-targets/${RUST_TARGET_SYS}.json ${D}${libdir}/rustlib/${RUST_TARGET_SYS}/target.json
 }
-
-# This makes sure that all .rlib files that Chromium needs get installed. The
-# libraries installed by libstd-rs don't include e.g. libprofiler_builtins.
-# Additionally, libstd and libtest installed by libstd-rs don't follow the usual
-# naming scheme, which would trip up Chromium.
-rust_do_install:class-target:append() {
-    mkdir -p _dist
-    rlib_path="rust-std-${PV}-${RUST_TARGET_SYS}/rust-std-${RUST_TARGET_SYS}/lib/rustlib"
-    tar -C _dist -xf build/dist/rust-std-${PV}-${RUST_TARGET_SYS}.tar.xz $rlib_path
-
-    target_dir=${D}${libdir}/rustlib
-    install -d $target_dir
-    cp -r _dist/$rlib_path/${RUST_TARGET_SYS} $target_dir
-    rm -rf _dist
-}
-
-# Override the default dependency on libstd-rs, as we copy the libraries
-# manually above.
-RUSTLIB_DEP = ""