Allow deps to be renamed

proto/proto.bzl

@@ -167,6 +167,7 @@ def _rust_proto_compile(protos, descriptor_sets, imports, crate_name, ctx, grpc,
             root = lib_rs,
             srcs = srcs,
             deps = compile_deps,
+            aliases = {},
             output = rust_lib,
             edition = proto_toolchain.edition,
         ),

rust/private/rust.bzl

@@ -120,6 +120,7 @@ def _rust_library_impl(ctx):
             root = lib_rs,
             srcs = ctx.files.srcs,
             deps = ctx.attr.deps,
+            aliases = ctx.attr.aliases,
             output = rust_lib,
             edition = _get_edition(ctx, toolchain),
         ),
@@ -143,6 +144,7 @@ def _rust_binary_impl(ctx):
             root = _crate_root_src(ctx, "main.rs"),
             srcs = ctx.files.srcs,
             deps = ctx.attr.deps,
+            aliases = ctx.attr.aliases,
             output = output,
             edition = _get_edition(ctx, toolchain),
         ),
@@ -168,6 +170,7 @@ def _rust_test_common(ctx, test_binary):
             root = crate.root,
             srcs = crate.srcs + ctx.files.srcs,
             deps = crate.deps + ctx.attr.deps,
+            aliases = ctx.attr.aliases,
             output = test_binary,
             edition = crate.edition,
         )
@@ -186,6 +189,7 @@ def _rust_test_common(ctx, test_binary):
             root = _crate_root_src(ctx),
             srcs = ctx.files.srcs,
             deps = ctx.attr.deps,
+            aliases = ctx.attr.aliases,
             output = test_binary,
             edition = _get_edition(ctx, toolchain),
         )
@@ -275,6 +279,13 @@ _rust_common_attrs = {
             linking a native library.
         """),
     ),
+    "aliases": attr.label_keyed_string_dict(
+        doc = _tidy("""
+            Remap crates to a new name or moniker for linkage to this target
+
+            These are other `rust_library` targets and will be presented as the new name given.
+        """),
+    ),
     "crate_features": attr.string_list(
         doc = _tidy("""
             List of features to enable for this crate.

rust/private/rustc.bzl

@@ -32,11 +32,19 @@ CrateInfo = provider(
         "root": "File: The source File entrypoint to this crate, eg. lib.rs",
         "srcs": "List[File]: All source Files that are part of the crate.",
         "deps": "List[Provider]: This crate's (rust or cc) dependencies' providers.",
+        "aliases": "Dict[Label, String]: Renamed and aliased crates",
         "output": "File: The output File that will be produced, depends on crate type.",
         "edition": "str: The edition of this crate.",
     },
 )
 
+AliasableDep = provider(
+    fields = {
+        "name": "str",
+        "dep": "CrateInfo",
+    }
+)
+
 DepInfo = provider(
     fields = {
         "direct_crates": "depset[CrateInfo]",
@@ -84,7 +92,7 @@ def get_lib_name(lib):
     else:
         return libname
 
-def collect_deps(deps, toolchain):
+def collect_deps(deps, aliases, toolchain):
     """
     Walks through dependencies and collects the transitive dependencies.
 
@@ -101,10 +109,17 @@ def collect_deps(deps, toolchain):
     transitive_crates = depset()
     transitive_dylibs = depset(order = "topological")  # dylib link flag ordering matters.
     transitive_staticlibs = depset()
+
+    aliases = {k.label: v for k,v in aliases.items()}
     for dep in deps:
         if CrateInfo in dep:
             # This dependency is a rust_library
-            direct_crates += [dep[CrateInfo]]
+            direct_dep = dep[CrateInfo]
+            aliasable_dep = AliasableDep(
+                name = aliases.get(dep.label, direct_dep.name),
+                dep = direct_dep,
+            )
+            direct_crates += [aliasable_dep]
             transitive_crates = depset([dep[CrateInfo]], transitive = [transitive_crates])
             transitive_crates = depset(transitive = [transitive_crates, dep[DepInfo].transitive_crates])
             transitive_dylibs = depset(transitive = [transitive_dylibs, dep[DepInfo].transitive_dylibs])
@@ -197,6 +212,7 @@ def rustc_compile_action(
 
     dep_info = collect_deps(
         crate_info.deps,
+        crate_info.aliases,
         toolchain,
     )
 
@@ -389,7 +405,7 @@ def add_crate_link_flags(args, dep_info):
     )
 
 def _crate_to_link_flag(crate_info):
-    return ["--extern", "{}={}".format(crate_info.name, crate_info.output.path)]
+    return ["--extern", "{}={}".format(crate_info.name, crate_info.dep.output.path)]
 
 def _get_crate_dirname(crate):
     return crate.output.dirname

rust/private/rustdoc_test.bzl

@@ -67,7 +67,7 @@ def _build_rustdoc_test_script(toolchain, dep_info, crate):
     link_search_flags = []
 
     link_flags += ["--extern=" + crate.name + "=" + crate.output.short_path]
-    link_flags += ["--extern=" + c.name + "=" + c.output.short_path for c in d.direct_crates.to_list()]
+    link_flags += ["--extern=" + c.name + "=" + c.dep.output.short_path for c in d.direct_crates.to_list()]
     link_search_flags += ["-Ldependency={}".format(dirname(c.output.short_path)) for c in d.transitive_crates.to_list()]
 
     link_flags += ["-ldylib=" + get_lib_name(lib) for lib in d.transitive_dylibs.to_list()]