chromium: Depend on libstd-rs instead of rust (#809)

chromium: Depend on libstd-rs instead of rust

Fixes #792.

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

In #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 #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 #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.

Also, while we're already reworking our Rust setup, we can remove the
remaining part of our bbappend for the rust recipe and instead inherit
the `rust-common` class, thereby inheriting `rust-target-config` (which
needs stuff from `rust-common`). This means we get the `target.json`
files the Rust compiler needs installed in the directory pointed to by
the `RUST_TARGET_PATH` environment variable.

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 <max@igalia.com>

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

@@ -4,7 +4,7 @@ require gn-utils.inc
 
 GTKIC_VERSION = "${@bb.utils.contains('PACKAGECONFIG', 'gtk4', '4', '3',d)}"
 
-inherit features_check gtk-icon-cache qemu
+inherit features_check gtk-icon-cache qemu rust-common
 
 # The actual directory name in out/ is irrelevant for GN.
 OUTPUT_DIR = "out/Release"
@@ -73,6 +73,7 @@ DEPENDS += " \
     jpeg \
     libdrm \
     libffi \
+    libstd-rs \
     libwebp \
     libxkbcommon \
     libxslt \
@@ -87,7 +88,6 @@ 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 <max@igalia.com>
  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 | 16 +++++++++++-----
+ 4 files changed, 55 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()
@@ -187,7 +196,16 @@ index 386258f..25fdedc 100755
 
      def copy_file(infile, outfile):
        depfile.write(f" {infile}")
-@@ -117,14 +119,19 @@ def main():
+@@ -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 +119,18 @@ def main():
        output_filename = f"lib{concise_name}.rlib"
 
        infile = os.path.join(rustlib_dir, f)
@@ -201,9 +219,8 @@ index 386258f..25fdedc 100755
 +      outfile = os.path.join(lib_output_dir, f)
        copy_file(infile, outfile)
 
-+    f = 'target.json'
-+    infile = os.path.join(rustlib_dir, '..', f)
-+    outfile = os.path.join(args.output, f)
++    infile = os.path.join(os.environ['RUST_TARGET_PATH'], f'{args.target}.json')
++    outfile = os.path.join(args.output, 'target.json')
 +    copy_file(infile, outfile)
 +
      depfile.write("\n")