Apply lint_config to Cargo build scripts

cargo/private/cargo_build_script_wrapper.bzl

@@ -52,6 +52,7 @@ def cargo_build_script(
         rustc_env = {},
         rustc_env_files = [],
         rustc_flags = [],
+        lint_config = None,
         visibility = None,
         tags = None,
         aliases = None,
@@ -160,6 +161,7 @@ def cargo_build_script(
         rustc_env_files (list of label, optional): Files containing additional environment variables to set for rustc
             when building the build script.
         rustc_flags (list, optional): List of compiler flags passed to `rustc`.
+        lint_config (Label, optional): Lints applied while compiling the build script.
         visibility (list of label, optional): Visibility to apply to the generated build script output.
         tags: (list of str, optional): Tags to apply to the generated build script output.
         aliases (dict, optional): Remap crates to a new name or moniker for linkage to this target. \
@@ -221,6 +223,7 @@ def cargo_build_script(
         rustc_env = rustc_env,
         rustc_env_files = rustc_env_files,
         rustc_flags = rustc_flags,
+        lint_config = lint_config,
         edition = edition,
         tags = binary_tags,
         aliases = aliases,

rust/private/rustc.bzl

@@ -1756,10 +1756,10 @@ def rustc_compile_action(
 
     # Add flags for any 'rustc' lints that are specified.
     #
-    # Exclude lints if we're building in the exec configuration to prevent crates
-    # used in build scripts from generating warnings.
+    # An explicit lint configuration belongs to the crate in either
+    # configuration, including first-party build scripts and procedural macros.
     lint_files = []
-    if hasattr(ctx.attr, "lint_config") and ctx.attr.lint_config and not is_exec_configuration(ctx):
+    if hasattr(ctx.attr, "lint_config") and ctx.attr.lint_config:
         rust_flags = rust_flags + ctx.attr.lint_config[LintsInfo].rustc_lint_flags
         lint_files = lint_files + ctx.attr.lint_config[LintsInfo].rustc_lint_files
 

test/unit/lint_flags/build.rs

@@ -0,0 +1 @@
+fn main() {}

test/unit/lint_flags/lint_flags_test.bzl

@@ -1,6 +1,7 @@
 """Unittest to verify compile_data (attribute) propagation"""
 
-load("@bazel_skylib//lib:unittest.bzl", "analysistest")
+load("@bazel_skylib//lib:unittest.bzl", "analysistest", "asserts")
+load("//cargo:defs.bzl", "cargo_build_script")
 load("//rust:defs.bzl", "rust_clippy", "rust_doc", "rust_library", "rust_lint_config")
 load("//test/unit:common.bzl", "assert_argv_contains", "assert_argv_contains_not")
 
@@ -29,9 +30,12 @@ def _extra_rustc_flags_present_test(ctx):
     target = analysistest.target_under_test(env)
     target_action_contains_flag(env, target, ctx.attr.rustc_flags)
 
-    # Check the exec configuration target does NOT contain.
     target = ctx.attr.lib_exec
-    target_action_contains_not_flag(env, target, ctx.attr.rustc_flags)
+    if ctx.attr.apply_in_exec:
+        asserts.true(env, any([action.mnemonic == "Rustc" for action in target.actions]), "expected an exec-configuration Rustc action")
+        target_action_contains_flag(env, target, ctx.attr.rustc_flags)
+    else:
+        target_action_contains_not_flag(env, target, ctx.attr.rustc_flags)
 
     return analysistest.end(env)
 
@@ -45,6 +49,7 @@ extra_rustc_flag_present_test = analysistest.make(
         "rustc_flags": attr.string_list(
             mandatory = True,
         ),
+        "apply_in_exec": attr.bool(),
     },
 )
 
@@ -64,6 +69,13 @@ def _define_test_targets():
         edition = "2018",
     )
 
+    cargo_build_script(
+        name = "script",
+        srcs = ["build.rs"],
+        lint_config = ":workspace_lints",
+        edition = "2018",
+    )
+
     rust_clippy(
         name = "clippy",
         deps = [":lib"],
@@ -91,6 +103,18 @@ def lint_flags_test_suite(name):
             "--allow=unknown_lints",
             "--check-cfg=cfg(bazel)",
         ],
+        apply_in_exec = True,
+    )
+
+    extra_rustc_flag_present_test(
+        name = "build_script_lints_apply_in_exec",
+        target_under_test = ":script_",
+        lib_exec = ":script_",
+        rustc_flags = [
+            "--allow=unknown_lints",
+            "--check-cfg=cfg(bazel)",
+        ],
+        apply_in_exec = True,
     )
 
     extra_rustc_flag_present_test(
@@ -111,6 +135,7 @@ def lint_flags_test_suite(name):
         name = name,
         tests = [
             ":rustc_lints_apply_flags",
+            ":build_script_lints_apply_in_exec",
             ":clippy_lints_apply_flags",
             ":rustdoc_lints_apply_flags",
         ],