Fix bzlmod examples on windows (#2454)

On windows (and some other platforms), the file extension of cargo,
rustc, etc have an extension. The module extension for loading crates
did not take this into account, causing it to error on windows.

Additionally, when using bzlmod to build vendored crates, the runfiles
tree would exceed the 260 char windows path limit. To mitigate this, I
have shortened the internal_deps module extension to just `i` and
changed the build script suffix to `_bs` from `_build_script`. This
makes the path names below the 260 char limit.

This makes the bzlmod CI run on windows, to avoid regressing this.
Currently gen_rust_project does not run on windows for other reasons,
although we do build this.

.bazelci/presubmit.yml

@@ -667,6 +667,16 @@ tasks:
       - "@rules_rust//tools/rust_analyzer:gen_rust_project"
     test_targets:
       - "//..."
+  windows_bzlmod_bcr:
+    name: bzlmod BCR presubmit
+    platform: windows
+    working_directory: examples/bzlmod/hello_world
+    run_targets:
+      - "//third-party:vendor"
+    build_targets:
+      - "@rules_rust//tools/rust_analyzer:gen_rust_project"
+    test_targets:
+      - "//..."
 
 buildifier:
   version: latest

.bcr/presubmit.yml

@@ -14,3 +14,20 @@ bcr_test_module:
         - "@rules_rust//tools/rust_analyzer:gen_rust_project"
       test_targets:
         - "//..."
+# Windows is run separately because currently gen_rust_project doesn't run on windows, although it does build
+bcr_test_module_windows:
+  module_path: ""
+  matrix:
+    bazel: ["6.x", "7.x"]
+  tasks:
+    run_tests:
+      working_directory: examples/bzlmod/hello_world
+      name: "Run test module"
+      platform: windows
+      bazel: ${{ bazel }}
+      run_targets:
+        - "//third-party:vendor"
+      build_targets:
+        - "@rules_rust//tools/rust_analyzer:gen_rust_project"
+      test_targets:
+        - "//..."

MODULE.bazel

@@ -36,7 +36,7 @@ bazel_dep(
     repo_name = "com_google_protobuf",
 )
 
-internal_deps = use_extension("//rust/private:extensions.bzl", "internal_deps")
+internal_deps = use_extension("//rust/private:extensions.bzl", "i")
 use_repo(
     internal_deps,
     "bazelci_rules",

cargo/private/cargo_build_script.bzl

@@ -415,8 +415,8 @@ def name_to_pkg_name(name):
     Returns:
         str: A cleaned up name for a build script target.
     """
-    if name.endswith("_build_script"):
-        return name[:-len("_build_script")]
+    if name.endswith("_bs"):
+        return name[:-len("_bs")]
     return name
 
 def _cargo_dep_env_implementation(ctx):