1// Copyright 2020 The Android Open Source Project
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package config
16
17import (
18	"fmt"
19	"strings"
20
21	"android/soong/android"
22)
23
24// Overarching principles for Rust lints on Android:
25// The Android build system tries to avoid reporting warnings during the build.
26// Therefore, by default, we upgrade warnings to denials. For some of these
27// lints, an allow exception is setup, using the variables below.
28//
29// The lints are split into two categories. The first one contains the built-in
30// lints (https://doc.rust-lang.org/rustc/lints/index.html). The second is
31// specific to Clippy lints (https://rust-lang.github.io/rust-clippy/master/).
32//
33// For both categories, there are 3 levels of linting possible:
34// - "android", for the strictest lints that applies to all Android platform code.
35// - "vendor", for relaxed rules.
36// - "none", to disable the linting.
37// There is a fourth option ("default") which automatically selects the linting level
38// based on the module's location. See defaultLintSetForPath.
39//
40// When developing a module, you may set `lints = "none"` and `clippy_lints =
41// "none"` to disable all the linting. Expect some questioning during code review
42// if you enable one of these options.
43var (
44	// Default Rust lints that applies to Google-authored modules.
45	defaultRustcLints = []string{
46		"-A deprecated",
47		"-D missing-docs",
48		"-D warnings",
49	}
50	// Default Clippy lints. These are applied on top of defaultRustcLints.
51	// It should be assumed that any warning lint will be promoted to a
52	// deny.
53	defaultClippyLints = []string{
54		"-A clippy::type-complexity",
55		"-A clippy::unnecessary-wraps",
56		"-A clippy::unusual-byte-groupings",
57		"-A clippy::upper-case-acronyms",
58	}
59
60	// Rust lints for vendor code.
61	defaultRustcVendorLints = []string{
62		"-A deprecated",
63		"-D warnings",
64	}
65	// Clippy lints for vendor source. These are applied on top of
66	// defaultRustcVendorLints.  It should be assumed that any warning lint
67	// will be promoted to a deny.
68	defaultClippyVendorLints = []string{
69		"-A clippy::complexity",
70		"-A clippy::perf",
71		"-A clippy::style",
72	}
73
74	// For prebuilts/ and external/, no linting is expected. If a warning
75	// or a deny is reported, it should be fixed upstream.
76	allowAllLints = []string{
77		"--cap-lints allow",
78	}
79)
80
81func init() {
82	// Default Rust lints. These apply to all Google-authored modules.
83	pctx.VariableFunc("RustDefaultLints", func(ctx android.PackageVarContext) string {
84		if override := ctx.Config().Getenv("RUST_DEFAULT_LINTS"); override != "" {
85			return override
86		}
87		return strings.Join(defaultRustcLints, " ")
88	})
89	pctx.VariableFunc("ClippyDefaultLints", func(ctx android.PackageVarContext) string {
90		if override := ctx.Config().Getenv("CLIPPY_DEFAULT_LINTS"); override != "" {
91			return override
92		}
93		return strings.Join(defaultClippyLints, " ")
94	})
95
96	// Rust lints that only applies to external code.
97	pctx.VariableFunc("RustVendorLints", func(ctx android.PackageVarContext) string {
98		if override := ctx.Config().Getenv("RUST_VENDOR_LINTS"); override != "" {
99			return override
100		}
101		return strings.Join(defaultRustcVendorLints, " ")
102	})
103	pctx.VariableFunc("ClippyVendorLints", func(ctx android.PackageVarContext) string {
104		if override := ctx.Config().Getenv("CLIPPY_VENDOR_LINTS"); override != "" {
105			return override
106		}
107		return strings.Join(defaultClippyVendorLints, " ")
108	})
109	pctx.StaticVariable("RustAllowAllLints", strings.Join(allowAllLints, " "))
110}
111
112const noLint = ""
113const rustcDefault = "${config.RustDefaultLints}"
114const rustcVendor = "${config.RustVendorLints}"
115const rustcAllowAll = "${config.RustAllowAllLints}"
116const clippyDefault = "${config.ClippyDefaultLints}"
117const clippyVendor = "${config.ClippyVendorLints}"
118
119// lintConfig defines a set of lints and clippy configuration.
120type lintConfig struct {
121	rustcConfig   string // for the lints to apply to rustc.
122	clippyEnabled bool   // to indicate if clippy should be executed.
123	clippyConfig  string // for the lints to apply to clippy.
124}
125
126const (
127	androidLints = "android"
128	vendorLints  = "vendor"
129	noneLints    = "none"
130)
131
132// lintSets defines the categories of linting for Android and their mapping to lintConfigs.
133var lintSets = map[string]lintConfig{
134	androidLints: {rustcDefault, true, clippyDefault},
135	vendorLints:  {rustcVendor, true, clippyVendor},
136	noneLints:    {rustcAllowAll, false, noLint},
137}
138
139type pathLintSet struct {
140	prefix string
141	set    string
142}
143
144// This is a map of local path prefixes to a lint set.  The first entry
145// matching will be used. If no entry matches, androidLints ("android") will be
146// used.
147var defaultLintSetForPath = []pathLintSet{
148	{"external", noneLints},
149	{"hardware", vendorLints},
150	{"prebuilts", noneLints},
151	{"vendor/google", androidLints},
152	{"vendor", vendorLints},
153}
154
155// ClippyLintsForDir returns a boolean if Clippy should be executed and if so, the lints to be used.
156func ClippyLintsForDir(dir string, clippyLintsProperty *string) (bool, string, error) {
157	if clippyLintsProperty != nil {
158		set, ok := lintSets[*clippyLintsProperty]
159		if ok {
160			return set.clippyEnabled, set.clippyConfig, nil
161		}
162		if *clippyLintsProperty != "default" {
163			return false, "", fmt.Errorf("unknown value for `clippy_lints`: %v, valid options are: default, android, vendor or none", *clippyLintsProperty)
164		}
165	}
166	for _, p := range defaultLintSetForPath {
167		if strings.HasPrefix(dir, p.prefix) {
168			setConfig := lintSets[p.set]
169			return setConfig.clippyEnabled, setConfig.clippyConfig, nil
170		}
171	}
172	return true, clippyDefault, nil
173}
174
175// RustcLintsForDir returns the standard lints to be used for a repository.
176func RustcLintsForDir(dir string, lintProperty *string) (string, error) {
177	if lintProperty != nil {
178		set, ok := lintSets[*lintProperty]
179		if ok {
180			return set.rustcConfig, nil
181		}
182		if *lintProperty != "default" {
183			return "", fmt.Errorf("unknown value for `lints`: %v, valid options are: default, android, vendor or none", *lintProperty)
184		}
185
186	}
187	for _, p := range defaultLintSetForPath {
188		if strings.HasPrefix(dir, p.prefix) {
189			return lintSets[p.set].rustcConfig, nil
190		}
191	}
192	return rustcDefault, nil
193}
194