-
Notifications
You must be signed in to change notification settings - Fork 728
/
UnusedMethod.java
330 lines (302 loc) · 12.9 KB
/
UnusedMethod.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
/*
* Copyright 2018 The Error Prone Authors.
*
* 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 com.google.errorprone.bugpatterns;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static com.google.common.collect.Iterables.getLast;
import static com.google.errorprone.BugPattern.SeverityLevel.WARNING;
import static com.google.errorprone.matchers.Matchers.SERIALIZATION_METHODS;
import static com.google.errorprone.suppliers.Suppliers.typeFromString;
import static com.google.errorprone.util.ASTHelpers.getSymbol;
import static com.google.errorprone.util.ASTHelpers.getType;
import static com.google.errorprone.util.ASTHelpers.isSubtype;
import static com.google.errorprone.util.MoreAnnotations.asStrings;
import static com.google.errorprone.util.MoreAnnotations.getAnnotationValue;
import com.google.common.base.Ascii;
import com.google.common.collect.ImmutableSet;
import com.google.errorprone.BugPattern;
import com.google.errorprone.VisitorState;
import com.google.errorprone.bugpatterns.BugChecker.CompilationUnitTreeMatcher;
import com.google.errorprone.fixes.SuggestedFixes;
import com.google.errorprone.matchers.Description;
import com.sun.source.tree.AnnotationTree;
import com.sun.source.tree.ClassTree;
import com.sun.source.tree.CompilationUnitTree;
import com.sun.source.tree.IdentifierTree;
import com.sun.source.tree.MemberReferenceTree;
import com.sun.source.tree.MemberSelectTree;
import com.sun.source.tree.MethodInvocationTree;
import com.sun.source.tree.MethodTree;
import com.sun.source.tree.Tree;
import com.sun.source.tree.Tree.Kind;
import com.sun.source.util.TreePath;
import com.sun.source.util.TreePathScanner;
import com.sun.source.util.TreeScanner;
import com.sun.tools.javac.code.Symbol;
import com.sun.tools.javac.code.Symbol.MethodSymbol;
import com.sun.tools.javac.code.Symbol.TypeSymbol;
import com.sun.tools.javac.code.Type;
import com.sun.tools.javac.tree.JCTree.JCAnnotation;
import com.sun.tools.javac.tree.JCTree.JCAssign;
import com.sun.tools.javac.tree.JCTree.JCExpression;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
import javax.lang.model.element.ElementKind;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.Name;
/** Bugpattern to detect unused declarations. */
@BugPattern(
name = "UnusedMethod",
altNames = {"Unused", "unused", "UnusedParameters"},
summary = "Unused.",
severity = WARNING,
documentSuppression = false)
public final class UnusedMethod extends BugChecker implements CompilationUnitTreeMatcher {
private static final String GWT_JAVASCRIPT_OBJECT = "com.google.gwt.core.client.JavaScriptObject";
private static final String EXEMPT_PREFIX = "unused";
private static final String JUNIT_PARAMS_VALUE = "value";
private static final String JUNIT_PARAMS_ANNOTATION_TYPE = "junitparams.Parameters";
private static final ImmutableSet<String> EXEMPTING_METHOD_ANNOTATIONS =
ImmutableSet.of(
"com.google.inject.Provides",
"com.google.inject.Inject",
"com.google.inject.multibindings.ProvidesIntoMap",
"com.google.inject.multibindings.ProvidesIntoSet",
"javax.annotation.PreDestroy",
"javax.annotation.PostConstruct",
"javax.persistence.PostLoad",
"javax.inject.Inject",
"org.testng.annotations.DataProvider");
/** The set of types exempting a type that is extending or implementing them. */
private static final ImmutableSet<String> EXEMPTING_SUPER_TYPES =
ImmutableSet.of(
);
@Override
public Description matchCompilationUnit(CompilationUnitTree tree, VisitorState state) {
// Map of symbols to method declarations. Initially this is a map of all of the methods. As we
// go we remove those variables which are used.
Map<Symbol, TreePath> unusedMethods = new HashMap<>();
// We will skip reporting on the whole compilation if there are any native methods found.
// Use a TreeScanner to find all local variables and fields.
if (hasNativeMethods(tree)) {
return Description.NO_MATCH;
}
AtomicBoolean ignoreUnusedMethods = new AtomicBoolean(false);
class MethodFinder extends TreePathScanner<Void, Void> {
@Override
public Void visitClass(ClassTree tree, Void unused) {
if (isSuppressed(tree) || exemptedBySuperType(getType(tree), state)) {
return null;
}
return super.visitClass(tree, null);
}
private boolean exemptedBySuperType(Type type, VisitorState state) {
return EXEMPTING_SUPER_TYPES.stream()
.anyMatch(t -> isSubtype(type, typeFromString(t).get(state), state));
}
@Override
public Void visitMethod(MethodTree tree, Void unused) {
if (hasJUnitParamsParametersForMethodAnnotation(tree.getModifiers().getAnnotations())) {
// Since this method uses @Parameters, there will be another method that appears to
// be unused. Don't warn about unusedMethods at all in this case.
ignoreUnusedMethods.set(true);
}
if (isSuppressed(tree)) {
// @SuppressWarnings("unused") applies to the entire AST, not just the symbol it's bound
// to. Skip the whole method.
return null;
}
if (isMethodSymbolEligibleForChecking(tree)) {
unusedMethods.put(getSymbol(tree), getCurrentPath());
}
return super.visitMethod(tree, unused);
}
private boolean hasJUnitParamsParametersForMethodAnnotation(
Collection<? extends AnnotationTree> annotations) {
for (AnnotationTree tree : annotations) {
JCAnnotation annotation = (JCAnnotation) tree;
if (annotation.getAnnotationType().type != null
&& annotation
.getAnnotationType()
.type
.toString()
.equals(JUNIT_PARAMS_ANNOTATION_TYPE)) {
if (annotation.getArguments().isEmpty()) {
// @Parameters, which uses implicit provider methods
return true;
}
for (JCExpression arg : annotation.getArguments()) {
if (arg.getKind() != Kind.ASSIGNMENT) {
// Implicit value annotation, e.g. @Parameters({"1"}); no exemption required.
return false;
}
JCExpression var = ((JCAssign) arg).getVariable();
if (var.getKind() == Kind.IDENTIFIER) {
// Anything that is not @Parameters(value = ...), e.g.
// @Parameters(source = ...) or @Parameters(method = ...)
if (!((IdentifierTree) var).getName().contentEquals(JUNIT_PARAMS_VALUE)) {
return true;
}
}
}
}
}
return false;
}
private boolean isMethodSymbolEligibleForChecking(MethodTree tree) {
if (exemptedByName(tree.getName())) {
return false;
}
// Assume the method is called if annotated with a called-reflectively annotation.
if (exemptedByAnnotation(tree.getModifiers().getAnnotations(), state)) {
return false;
}
// Skip constructors and special methods.
MethodSymbol methodSymbol = getSymbol(tree);
if (methodSymbol == null
|| methodSymbol.getKind() == ElementKind.CONSTRUCTOR
|| SERIALIZATION_METHODS.matches(tree, state)) {
return false;
}
// Ignore this method if the last parameter is a GWT JavaScriptObject.
if (!tree.getParameters().isEmpty()) {
Type lastParamType = getType(getLast(tree.getParameters()));
if (lastParamType != null && lastParamType.toString().equals(GWT_JAVASCRIPT_OBJECT)) {
return false;
}
}
return tree.getModifiers().getFlags().contains(Modifier.PRIVATE);
}
}
new MethodFinder().scan(state.getPath(), null);
class FilterUsedMethods extends TreePathScanner<Void, Void> {
@Override
public Void visitMemberSelect(MemberSelectTree memberSelectTree, Void unused) {
Symbol symbol = getSymbol(memberSelectTree);
unusedMethods.remove(symbol);
return super.visitMemberSelect(memberSelectTree, null);
}
@Override
public Void visitMemberReference(MemberReferenceTree tree, Void unused) {
super.visitMemberReference(tree, null);
MethodSymbol symbol = getSymbol(tree);
unusedMethods.remove(symbol);
if (symbol != null) {
symbol.getParameters().forEach(unusedMethods::remove);
}
return null;
}
@Override
public Void visitMethodInvocation(MethodInvocationTree tree, Void unused) {
Symbol methodSymbol = getSymbol(tree);
if (methodSymbol != null) {
unusedMethods.remove(methodSymbol);
}
super.visitMethodInvocation(tree, null);
return null;
}
@Override
public Void visitMethod(MethodTree tree, Void unused) {
handleMethodSource(tree);
super.visitMethod(tree, null);
return null;
}
/**
* If a method is annotated with @MethodSource, the annotation value refers to another method
* that is used reflectively to supply test parameters, so that method should not be
* considered unused.
*/
private void handleMethodSource(MethodTree tree) {
MethodSymbol sym = getSymbol(tree);
if (sym == null) {
return;
}
Name name = state.getName("org.junit.jupiter.params.provider.MethodSource");
sym.getRawAttributes().stream()
.filter(a -> a.type.tsym.getQualifiedName().equals(name))
.findAny()
// get the annotation value array as a set of Names
.flatMap(a -> getAnnotationValue(a, "value"))
.map(
y -> asStrings(y).map(state::getName).map(Name::toString).collect(toImmutableSet()))
// remove all potentially unused methods referenced by the @MethodSource
.ifPresent(
referencedNames ->
unusedMethods
.entrySet()
.removeIf(
e -> {
Symbol unusedSym = e.getKey();
String simpleName = unusedSym.getSimpleName().toString();
return referencedNames.contains(simpleName)
|| referencedNames.contains(
unusedSym.owner.getQualifiedName() + "#" + simpleName);
}));
}
}
new FilterUsedMethods().scan(state.getPath(), null);
if (ignoreUnusedMethods.get()) {
return Description.NO_MATCH;
}
for (TreePath unusedPath : unusedMethods.values()) {
Tree unusedTree = unusedPath.getLeaf();
String message =
String.format("Private method '%s' is never used.", ((MethodTree) unusedTree).getName());
state.reportMatch(
buildDescription(unusedTree)
.addFix(SuggestedFixes.replaceIncludingComments(unusedPath, "", state))
.setMessage(message)
.build());
}
return Description.NO_MATCH;
}
static boolean hasNativeMethods(CompilationUnitTree tree) {
AtomicBoolean hasAnyNativeMethods = new AtomicBoolean(false);
new TreeScanner<Void, Void>() {
@Override
public Void visitMethod(MethodTree tree, Void unused) {
if (tree.getModifiers().getFlags().contains(Modifier.NATIVE)) {
hasAnyNativeMethods.set(true);
}
return null;
}
}.scan(tree, null);
return hasAnyNativeMethods.get();
}
/**
* Looks at the list of {@code annotations} and see if there is any annotation which exists {@code
* exemptingAnnotations}.
*/
private static boolean exemptedByAnnotation(
List<? extends AnnotationTree> annotations, VisitorState state) {
for (AnnotationTree annotation : annotations) {
Type annotationType = getType(annotation);
if (annotationType == null) {
continue;
}
TypeSymbol tsym = annotationType.tsym;
if (EXEMPTING_METHOD_ANNOTATIONS.contains(tsym.getQualifiedName().toString())) {
return true;
}
}
return false;
}
private static boolean exemptedByName(Name name) {
return Ascii.toLowerCase(name.toString()).startsWith(EXEMPT_PREFIX);
}
}