Handle files from external repos (fix breaking change in Bazel 3.7.0)

rust/private/rust.bzl

@@ -127,6 +127,34 @@ def get_edition(attr, toolchain, label):
     else:
         return toolchain.default_edition
 
+def _symlink_for_non_generated_source(ctx, src_file, package_root):
+    """Creates and returns a symlink for non-generated source files.
+
+    This rule uses the full path to the source files and the rule directory to compute
+    the relative paths. This is needed, instead of using `short_path`, because of non-generated
+    source files in external repositories returning relative paths.
+
+    Args:
+        ctx (struct): The current rule's context.
+        src_file (File): The source file.
+        package_root (File): The full path to the directory containing the current rule.
+
+    Returns:
+        File: The created symlink if a non-generated file, or the file itself.
+    """
+
+    if src_file.is_source or src_file.root.path != ctx.bin_dir.path:
+        src_short_path = paths.relativize(src_file.path, src_file.root.path)
+        src_symlink = ctx.actions.declare_file(paths.relativize(src_short_path, package_root))
+        ctx.actions.symlink(
+            output = src_symlink,
+            target_file = src_file,
+            progress_message = "Creating symlink to source file: {}".format(src_file.path),
+        )
+        return src_symlink
+    else:
+        return src_file
+
 def _transform_sources(ctx, srcs, crate_root):
     """Creates symlinks of the source files if needed.
 
@@ -151,36 +179,13 @@ def _transform_sources(ctx, srcs, crate_root):
     if not has_generated_sources:
         return srcs, crate_root
 
-    generated_sources = []
-
+    package_root = paths.dirname(paths.join(ctx.label.workspace_root, ctx.build_file_path))
+    generated_sources = [_symlink_for_non_generated_source(ctx, src, package_root) for src in srcs if src != crate_root]
     generated_root = crate_root
-    package_root = paths.dirname(ctx.build_file_path)
-
-    if crate_root and (crate_root.is_source or crate_root.root.path != ctx.bin_dir.path):
-        generated_root = ctx.actions.declare_file(paths.relativize(crate_root.short_path, package_root))
-        ctx.actions.symlink(
-            output = generated_root,
-            target_file = crate_root,
-            progress_message = "Creating symlink to source file: {}".format(crate_root.path),
-        )
-    if generated_root:
+    if crate_root:
+        generated_root = _symlink_for_non_generated_source(ctx, crate_root, package_root)
         generated_sources.append(generated_root)
 
-    for src in srcs:
-        # We took care of the crate root above.
-        if src == crate_root:
-            continue
-        if src.is_source or src.root.path != ctx.bin_dir.path:
-            src_symlink = ctx.actions.declare_file(paths.relativize(src.short_path, package_root))
-            ctx.actions.symlink(
-                output = src_symlink,
-                target_file = src,
-                progress_message = "Creating symlink to source file: {}".format(src.path),
-            )
-            generated_sources.append(src_symlink)
-        else:
-            generated_sources.append(src)
-
     return generated_sources, generated_root
 
 def _rust_library_impl(ctx):