1 //=== LLVMConventionsChecker.cpp - Check LLVM codebase conventions ---*- C++ -*-
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This defines LLVMConventionsChecker, a bunch of small little checks
11 // for checking specific coding conventions in the LLVM/Clang codebase.
13 //===----------------------------------------------------------------------===//
15 #include "ClangSACheckers.h"
16 #include "clang/StaticAnalyzer/Core/Checker.h"
17 #include "clang/StaticAnalyzer/Core/BugReporter/BugReporter.h"
18 #include "clang/AST/DeclTemplate.h"
19 #include "clang/AST/StmtVisitor.h"
21 #include "llvm/ADT/StringRef.h"
23 using namespace clang;
26 //===----------------------------------------------------------------------===//
27 // Generic type checking routines.
28 //===----------------------------------------------------------------------===//
30 static bool IsLLVMStringRef(QualType T) {
31 const RecordType *RT = T->getAs<RecordType>();
35 return StringRef(QualType(RT, 0).getAsString()) ==
39 /// Check whether the declaration is semantically inside the top-level
40 /// namespace named by ns.
41 static bool InNamespace(const Decl *D, StringRef NS) {
42 const NamespaceDecl *ND = dyn_cast<NamespaceDecl>(D->getDeclContext());
45 const IdentifierInfo *II = ND->getIdentifier();
46 if (!II || !II->getName().equals(NS))
48 return isa<TranslationUnitDecl>(ND->getDeclContext());
51 static bool IsStdString(QualType T) {
52 if (const ElaboratedType *QT = T->getAs<ElaboratedType>())
53 T = QT->getNamedType();
55 const TypedefType *TT = T->getAs<TypedefType>();
59 const TypedefNameDecl *TD = TT->getDecl();
61 if (!InNamespace(TD, "std"))
64 return TD->getName() == "string";
67 static bool IsClangType(const RecordDecl *RD) {
68 return RD->getName() == "Type" && InNamespace(RD, "clang");
71 static bool IsClangDecl(const RecordDecl *RD) {
72 return RD->getName() == "Decl" && InNamespace(RD, "clang");
75 static bool IsClangStmt(const RecordDecl *RD) {
76 return RD->getName() == "Stmt" && InNamespace(RD, "clang");
79 static bool IsClangAttr(const RecordDecl *RD) {
80 return RD->getName() == "Attr" && InNamespace(RD, "clang");
83 static bool IsStdVector(QualType T) {
84 const TemplateSpecializationType *TS = T->getAs<TemplateSpecializationType>();
88 TemplateName TM = TS->getTemplateName();
89 TemplateDecl *TD = TM.getAsTemplateDecl();
91 if (!TD || !InNamespace(TD, "std"))
94 return TD->getName() == "vector";
97 static bool IsSmallVector(QualType T) {
98 const TemplateSpecializationType *TS = T->getAs<TemplateSpecializationType>();
102 TemplateName TM = TS->getTemplateName();
103 TemplateDecl *TD = TM.getAsTemplateDecl();
105 if (!TD || !InNamespace(TD, "llvm"))
108 return TD->getName() == "SmallVector";
111 //===----------------------------------------------------------------------===//
112 // CHECK: a StringRef should not be bound to a temporary std::string whose
113 // lifetime is shorter than the StringRef's.
114 //===----------------------------------------------------------------------===//
117 class StringRefCheckerVisitor : public StmtVisitor<StringRefCheckerVisitor> {
120 StringRefCheckerVisitor(BugReporter &br) : BR(br) {}
121 void VisitChildren(Stmt *S) {
122 for (Stmt::child_iterator I = S->child_begin(), E = S->child_end() ;
124 if (Stmt *child = *I)
127 void VisitStmt(Stmt *S) { VisitChildren(S); }
128 void VisitDeclStmt(DeclStmt *DS);
130 void VisitVarDecl(VarDecl *VD);
132 } // end anonymous namespace
134 static void CheckStringRefAssignedTemporary(const Decl *D, BugReporter &BR) {
135 StringRefCheckerVisitor walker(BR);
136 walker.Visit(D->getBody());
139 void StringRefCheckerVisitor::VisitDeclStmt(DeclStmt *S) {
142 for (DeclStmt::decl_iterator I = S->decl_begin(), E = S->decl_end();I!=E; ++I)
143 if (VarDecl *VD = dyn_cast<VarDecl>(*I))
147 void StringRefCheckerVisitor::VisitVarDecl(VarDecl *VD) {
148 Expr *Init = VD->getInit();
152 // Pattern match for:
153 // StringRef x = call() (where call returns std::string)
154 if (!IsLLVMStringRef(VD->getType()))
156 ExprWithCleanups *Ex1 = dyn_cast<ExprWithCleanups>(Init);
159 CXXConstructExpr *Ex2 = dyn_cast<CXXConstructExpr>(Ex1->getSubExpr());
160 if (!Ex2 || Ex2->getNumArgs() != 1)
162 ImplicitCastExpr *Ex3 = dyn_cast<ImplicitCastExpr>(Ex2->getArg(0));
165 CXXConstructExpr *Ex4 = dyn_cast<CXXConstructExpr>(Ex3->getSubExpr());
166 if (!Ex4 || Ex4->getNumArgs() != 1)
168 ImplicitCastExpr *Ex5 = dyn_cast<ImplicitCastExpr>(Ex4->getArg(0));
171 CXXBindTemporaryExpr *Ex6 = dyn_cast<CXXBindTemporaryExpr>(Ex5->getSubExpr());
172 if (!Ex6 || !IsStdString(Ex6->getType()))
175 // Okay, badness! Report an error.
176 const char *desc = "StringRef should not be bound to temporary "
177 "std::string that it outlives";
178 PathDiagnosticLocation VDLoc =
179 PathDiagnosticLocation::createBegin(VD, BR.getSourceManager());
180 BR.EmitBasicReport(desc, "LLVM Conventions", desc,
181 VDLoc, Init->getSourceRange());
184 //===----------------------------------------------------------------------===//
185 // CHECK: Clang AST nodes should not have fields that can allocate
187 //===----------------------------------------------------------------------===//
189 static bool AllocatesMemory(QualType T) {
190 return IsStdVector(T) || IsStdString(T) || IsSmallVector(T);
193 // This type checking could be sped up via dynamic programming.
194 static bool IsPartOfAST(const CXXRecordDecl *R) {
195 if (IsClangStmt(R) || IsClangType(R) || IsClangDecl(R) || IsClangAttr(R))
198 for (CXXRecordDecl::base_class_const_iterator I = R->bases_begin(),
199 E = R->bases_end(); I!=E; ++I) {
200 CXXBaseSpecifier BS = *I;
201 QualType T = BS.getType();
202 if (const RecordType *baseT = T->getAs<RecordType>()) {
203 CXXRecordDecl *baseD = cast<CXXRecordDecl>(baseT->getDecl());
204 if (IsPartOfAST(baseD))
213 class ASTFieldVisitor {
214 SmallVector<FieldDecl*, 10> FieldChain;
215 const CXXRecordDecl *Root;
218 ASTFieldVisitor(const CXXRecordDecl *root, BugReporter &br)
219 : Root(root), BR(br) {}
221 void Visit(FieldDecl *D);
222 void ReportError(QualType T);
224 } // end anonymous namespace
226 static void CheckASTMemory(const CXXRecordDecl *R, BugReporter &BR) {
230 for (RecordDecl::field_iterator I = R->field_begin(), E = R->field_end();
232 ASTFieldVisitor walker(R, BR);
237 void ASTFieldVisitor::Visit(FieldDecl *D) {
238 FieldChain.push_back(D);
240 QualType T = D->getType();
242 if (AllocatesMemory(T))
245 if (const RecordType *RT = T->getAs<RecordType>()) {
246 const RecordDecl *RD = RT->getDecl()->getDefinition();
247 for (RecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end();
252 FieldChain.pop_back();
255 void ASTFieldVisitor::ReportError(QualType T) {
256 llvm::SmallString<1024> buf;
257 llvm::raw_svector_ostream os(buf);
259 os << "AST class '" << Root->getName() << "' has a field '"
260 << FieldChain.front()->getName() << "' that allocates heap memory";
261 if (FieldChain.size() > 1) {
262 os << " via the following chain: ";
264 for (SmallVectorImpl<FieldDecl*>::iterator I=FieldChain.begin(),
265 E=FieldChain.end(); I!=E; ++I) {
270 os << (*I)->getName();
273 os << " (type " << FieldChain.back()->getType().getAsString() << ")";
276 // Note that this will fire for every translation unit that uses this
277 // class. This is suboptimal, but at least scan-build will merge
278 // duplicate HTML reports. In the future we need a unified way of merging
279 // duplicate reports across translation units. For C++ classes we cannot
280 // just report warnings when we see an out-of-line method definition for a
281 // class, as that heuristic doesn't always work (the complete definition of
282 // the class may be in the header file, for example).
283 PathDiagnosticLocation L = PathDiagnosticLocation::createBegin(
284 FieldChain.front(), BR.getSourceManager());
285 BR.EmitBasicReport("AST node allocates heap memory", "LLVM Conventions",
289 //===----------------------------------------------------------------------===//
290 // LLVMConventionsChecker
291 //===----------------------------------------------------------------------===//
294 class LLVMConventionsChecker : public Checker<
295 check::ASTDecl<CXXRecordDecl>,
296 check::ASTCodeBody > {
298 void checkASTDecl(const CXXRecordDecl *R, AnalysisManager& mgr,
299 BugReporter &BR) const {
300 if (R->isCompleteDefinition())
301 CheckASTMemory(R, BR);
304 void checkASTCodeBody(const Decl *D, AnalysisManager& mgr,
305 BugReporter &BR) const {
306 CheckStringRefAssignedTemporary(D, BR);
311 void ento::registerLLVMConventionsChecker(CheckerManager &mgr) {
312 mgr.registerChecker<LLVMConventionsChecker>();