Merge "Explicitly define Rust default lints"

rust/builder.go

@@ -46,7 +46,7 @@ var (
 				// Because clippy-driver uses rustc as backend, we need to have some output even during the linting.
 				// Use the metadata output as it has the smallest footprint.
 				"--emit metadata -o $out $in ${libFlags} " +
-				"$clippyFlags $rustcFlags",
+				"$rustcFlags $clippyFlags",
 			CommandDeps: []string{"$clippyCmd"},
 		},
 		"rustcFlags", "libFlags", "clippyFlags")

rust/compiler.go

@@ -28,10 +28,6 @@ func getEdition(compiler *baseCompiler) string {
 	return proptools.StringDefault(compiler.Properties.Edition, config.DefaultEdition)
 }
 
-func getDenyWarnings(compiler *baseCompiler) bool {
-	return BoolDefault(compiler.Properties.Deny_warnings, config.DefaultDenyWarnings)
-}
-
 func (compiler *baseCompiler) setNoStdlibs() {
 	compiler.Properties.No_stdlibs = proptools.BoolPtr(true)
 }
@@ -56,8 +52,8 @@ type BaseCompilerProperties struct {
 	// path to the source file that is the main entry point of the program (e.g. main.rs or lib.rs)
 	Srcs []string `android:"path,arch_variant"`
 
-	// whether to pass "-D warnings" to rustc. Defaults to true.
+	// whether to suppress the standard lint flags - default to false
-	Deny_warnings *bool
+	No_lint *bool
 
 	// flags to pass to rustc
 	Flags []string `android:"path,arch_variant"`
@@ -145,8 +141,8 @@ func (compiler *baseCompiler) featuresToFlags(features []string) []string {
 
 func (compiler *baseCompiler) compilerFlags(ctx ModuleContext, flags Flags) Flags {
 
-	if getDenyWarnings(compiler) {
+	if !Bool(compiler.Properties.No_lint) {
-		flags.RustFlags = append(flags.RustFlags, "-D warnings")
+		flags.RustFlags = append(flags.RustFlags, config.RustcLintsForDir(ctx.ModuleDir()))
 	}
 	flags.RustFlags = append(flags.RustFlags, compiler.Properties.Flags...)
 	flags.RustFlags = append(flags.RustFlags, compiler.featuresToFlags(compiler.Properties.Features)...)

rust/config/Android.bp

@@ -9,7 +9,7 @@ bootstrap_go_package {
         "arm_device.go",
         "arm64_device.go",
         "global.go",
-        "clippy.go",
+        "lints.go",
         "toolchain.go",
         "allowed_list.go",
         "x86_darwin_host.go",

rust/config/clippy.go

@@ -1,80 +0,0 @@
-// Copyright 2020 The Android Open Source Project
-//
-// Licensed under the Apache License, Version 2.0 (the "License");
-// you may not use this file except in compliance with the License.
-// You may obtain a copy of the License at
-//
-//     http://www.apache.org/licenses/LICENSE-2.0
-//
-// Unless required by applicable law or agreed to in writing, software
-// distributed under the License is distributed on an "AS IS" BASIS,
-// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-// See the License for the specific language governing permissions and
-// limitations under the License.
-
-package config
-
-import (
-	"strings"
-
-	"android/soong/android"
-)
-
-var (
-	defaultLints = []string{
-		"-D missing-docs",
-		"-D clippy::missing-safety-doc",
-	}
-	defaultVendorLints = []string{
-		"",
-	}
-)
-
-func init() {
-	// Default Rust lints. These apply to all Google-authored modules.
-	pctx.VariableFunc("ClippyDefaultLints", func(ctx android.PackageVarContext) string {
-		if override := ctx.Config().Getenv("CLIPPY_DEFAULT_LINTS"); override != "" {
-			return override
-		}
-		return strings.Join(defaultLints, " ")
-	})
-
-	// Rust lints that only applies to external code.
-	pctx.VariableFunc("ClippyVendorLints", func(ctx android.PackageVarContext) string {
-		if override := ctx.Config().Getenv("CLIPPY_VENDOR_LINTS"); override != "" {
-			return override
-		}
-		return strings.Join(defaultVendorLints, " ")
-	})
-}
-
-type PathBasedClippyConfig struct {
-	PathPrefix   string
-	Enabled      bool
-	ClippyConfig string
-}
-
-const clippyNone = ""
-const clippyDefault = "${config.ClippyDefaultLints}"
-const clippyVendor = "${config.ClippyVendorLints}"
-
-// This is a map of local path prefixes to a boolean indicating if the lint
-// rule should be generated and if so, the set of lints to use. The first entry
-// matching will be used. If no entry is matching, clippyDefault will be used.
-var DefaultLocalTidyChecks = []PathBasedClippyConfig{
-	{"external/", false, clippyNone},
-	{"hardware/", true, clippyVendor},
-	{"prebuilts/", false, clippyNone},
-	{"vendor/google", true, clippyDefault},
-	{"vendor/", true, clippyVendor},
-}
-
-// ClippyLintsForDir returns the Clippy lints to be used for a repository.
-func ClippyLintsForDir(dir string) (bool, string) {
-	for _, pathCheck := range DefaultLocalTidyChecks {
-		if strings.HasPrefix(dir, pathCheck.PathPrefix) {
-			return pathCheck.Enabled, pathCheck.ClippyConfig
-		}
-	}
-	return true, clippyDefault
-}

rust/config/global.go

@@ -32,8 +32,6 @@ var (
 		"libtest",
 	}
 
-	DefaultDenyWarnings = true
-
 	GlobalRustFlags = []string{
 		"--remap-path-prefix $$(pwd)=",
 		"-C codegen-units=1",

rust/config/lints.go

@@ -0,0 +1,150 @@
+// Copyright 2020 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package config
+
+import (
+	"strings"
+
+	"android/soong/android"
+)
+
+// Overarching principles for Rust lints on Android:
+// The Android build system tries to avoid reporting warnings during the build.
+// Therefore, by default, we upgrade warnings to denials. For some of these
+// lints, an allow exception is setup, using the variables below.
+// There are different default lints depending on the repository location (see
+// DefaultLocalClippyChecks).
+// The lints are split into two categories. The first one contains the built-in
+// lints (https://doc.rust-lang.org/rustc/lints/index.html). The second is
+// specific to Clippy lints (https://rust-lang.github.io/rust-clippy/master/).
+//
+// When developing a module, it is possible to use the `no_lint` property to
+// disable the built-in lints configuration. It is also possible to set
+// `clippy` to false to disable the clippy verification. Expect some
+// questioning during review if you enable one of these options. For external/
+// code, if you need to use them, it is likely a bug. Otherwise, it may be
+// useful to add an exception (that is, move a lint from deny to allow).
+var (
+	// Default Rust lints that applies to Google-authored modules.
+	defaultRustcLints = []string{
+		"-A deprecated",
+		"-D missing-docs",
+		"-D warnings",
+	}
+	// Default Clippy lints. These are applied on top of defaultRustcLints.
+	// It should be assumed that any warning lint will be promoted to a
+	// deny.
+	defaultClippyLints = []string{
+		"-A clippy::type-complexity",
+	}
+
+	// Rust lints for vendor code.
+	defaultRustcVendorLints = []string{
+		"-A deprecated",
+		"-D warnings",
+	}
+	// Clippy lints for vendor source. These are applied on top of
+	// defaultRustcVendorLints.  It should be assumed that any warning lint
+	// will be promoted to a deny.
+	defaultClippyVendorLints = []string{
+		"-A clippy::complexity",
+		"-A clippy::perf",
+		"-A clippy::style",
+	}
+
+	// For prebuilts/ and external/, no linting is expected. If a warning
+	// or a deny is reported, it should be fixed upstream.
+	allowAllLints = []string{
+		"--cap-lints allow",
+	}
+)
+
+func init() {
+	// Default Rust lints. These apply to all Google-authored modules.
+	pctx.VariableFunc("RustDefaultLints", func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv("RUST_DEFAULT_LINTS"); override != "" {
+			return override
+		}
+		return strings.Join(defaultRustcLints, " ")
+	})
+	pctx.VariableFunc("ClippyDefaultLints", func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv("CLIPPY_DEFAULT_LINTS"); override != "" {
+			return override
+		}
+		return strings.Join(defaultClippyLints, " ")
+	})
+
+	// Rust lints that only applies to external code.
+	pctx.VariableFunc("RustVendorLints", func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv("RUST_VENDOR_LINTS"); override != "" {
+			return override
+		}
+		return strings.Join(defaultRustcVendorLints, " ")
+	})
+	pctx.VariableFunc("ClippyVendorLints", func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv("CLIPPY_VENDOR_LINTS"); override != "" {
+			return override
+		}
+		return strings.Join(defaultClippyVendorLints, " ")
+	})
+	pctx.StaticVariable("RustAllowAllLints", strings.Join(allowAllLints, " "))
+}
+
+type PathBasedClippyConfig struct {
+	PathPrefix    string
+	RustcConfig   string
+	ClippyEnabled bool
+	ClippyConfig  string
+}
+
+const noLint = ""
+const rustcDefault = "${config.RustDefaultLints}"
+const rustcVendor = "${config.RustVendorLints}"
+const rustcAllowAll = "${config.RustAllowAllLints}"
+const clippyDefault = "${config.ClippyDefaultLints}"
+const clippyVendor = "${config.ClippyVendorLints}"
+
+// This is a map of local path prefixes to a set of parameters for the linting:
+// - a string for the lints to apply to rustc.
+// - a boolean to indicate if clippy should be executed.
+// - a string for the lints to apply to clippy.
+// The first entry matching will be used.
+var DefaultLocalClippyChecks = []PathBasedClippyConfig{
+	{"external/", rustcAllowAll, false, noLint},
+	{"hardware/", rustcVendor, true, clippyVendor},
+	{"prebuilts/", rustcAllowAll, false, noLint},
+	{"vendor/google", rustcDefault, true, clippyDefault},
+	{"vendor/", rustcVendor, true, clippyVendor},
+}
+
+// ClippyLintsForDir returns a boolean if Clippy should be executed and if so, the lints to be used.
+func ClippyLintsForDir(dir string) (bool, string) {
+	for _, pathCheck := range DefaultLocalClippyChecks {
+		if strings.HasPrefix(dir, pathCheck.PathPrefix) {
+			return pathCheck.ClippyEnabled, pathCheck.ClippyConfig
+		}
+	}
+	return true, clippyDefault
+}
+
+// RustcLintsForDir returns the standard lints to be used for a repository.
+func RustcLintsForDir(dir string) string {
+	for _, pathCheck := range DefaultLocalClippyChecks {
+		if strings.HasPrefix(dir, pathCheck.PathPrefix) {
+			return pathCheck.RustcConfig
+		}
+	}
+	return rustcDefault
+}