rust: Update "do_update_snapshot" task for rust-snapshot.inc

The 'do_update_snapshot' task is failed with below error:
Exception: FileNotFoundError: [Errno 2] No such file or directory: '.../rustc-1.83.0-src/src/stage0.json'

There are changes in use of key-value format in stage0 file in
rust sources and the rust recipe should be apdated for that.

Changes in rust:
rust-lang/rust@1adfffd

(From OE-Core rev: 5f25af08ec364d5ed834c5b67ac8609459419fbf)

Signed-off-by: Yash Shinde <[email protected]>
Signed-off-by: Richard Purdie <[email protected]>

Author: Yashinde145

meta/recipes-devtools/rust/rust_1.84.1.bb

@@ -327,35 +327,48 @@ python do_update_snapshot() {
 
     from collections import defaultdict
 
-    with open(os.path.join(d.getVar("S"), "src", "stage0.json")) as f:
-        j = json.load(f)
-
-    config_dist_server = j['config']['dist_server']
-    compiler_date = j['compiler']['date']
-    compiler_version = j['compiler']['version']
+    key_value_pairs = {}
+    with open(os.path.join(d.getVar("S"), "src", "stage0")) as f:
+        for line in f:
+            # Skip empty lines or comments
+            if not line.strip() or line.startswith("#"):
+                continue
+            # Split the line into key and value using '=' as separator
+            match = re.match(r'(\S+)\s*=\s*(\S+)', line.strip())
+            if match:
+                key = match.group(1)
+                value = match.group(2)
+                key_value_pairs[key] = value
+    # Extract the required values from key_value_pairs
+    config_dist_server = key_value_pairs.get('dist_server', '')
+    compiler_date = key_value_pairs.get('compiler_date', '')
+    compiler_version = key_value_pairs.get('compiler_version', '')
 
     src_uri = defaultdict(list)
-    for k, v in j['checksums_sha256'].items():
-        m = re.search(f"dist/{compiler_date}/(?P<component>.*)-{compiler_version}-(?P<arch>.*)-unknown-linux-gnu\\.tar\\.xz", k)
-        if m:
-            component = m.group('component')
-            arch = m.group('arch')
-            src_uri[arch].append(f"SRC_URI[{component}-snapshot-{arch}.sha256sum] = \"{v}\"")
-
+    # Assuming checksums_sha256 is now a key-value pair like: checksum_key = checksum_value
+    for k, v in key_value_pairs.items():
+        # Match the pattern for checksums
+        if "dist" in k and "tar.xz" in k:
+            m = re.search(f"dist/{compiler_date}/(?P<component>.*)-{compiler_version}-(?P<arch>.*)-unknown-linux-gnu\\.tar\\.xz", k)
+            if m:
+                component = m.group('component')
+                arch = m.group('arch')
+                src_uri[arch].append(f"SRC_URI[{component}-snapshot-{arch}.sha256sum] = \"{v}\"")
+    # Create the snapshot string with the extracted values
     snapshot = """\
 ## This is information on the rust-snapshot (binary) used to build our current release.
-## snapshot info is taken from rust/src/stage0.json
+## snapshot info is taken from rust/src/stage0
 ## Rust is self-hosting and bootstraps itself with a pre-built previous version of itself.
 ## The exact (previous) version that has been used is specified in the source tarball.
 ## The version is replicated here.
 
 SNAPSHOT_VERSION = "%s"
 
 """ % compiler_version
-
+    # Add the checksum components to the snapshot
     for arch, components in src_uri.items():
         snapshot += "\n".join(components) + "\n\n"
-
+    # Add the additional snapshot URIs
     snapshot += """\
 SRC_URI += " \\
     ${RUST_DIST_SERVER}/dist/${RUST_STD_SNAPSHOT}.tar.xz;name=rust-std-snapshot-${RUST_BUILD_ARCH};subdir=rust-snapshot-components \\
@@ -369,7 +382,7 @@ RUST_STD_SNAPSHOT = "rust-std-${SNAPSHOT_VERSION}-${RUST_BUILD_ARCH}-unknown-lin
 RUSTC_SNAPSHOT = "rustc-${SNAPSHOT_VERSION}-${RUST_BUILD_ARCH}-unknown-linux-gnu"
 CARGO_SNAPSHOT = "cargo-${SNAPSHOT_VERSION}-${RUST_BUILD_ARCH}-unknown-linux-gnu"
 """ % config_dist_server
-
+    # Write the updated snapshot information to the rust-snapshot.inc file
     with open(os.path.join(d.getVar("THISDIR"), "rust-snapshot.inc"), "w") as f:
         f.write(snapshot)
 }