Bug Summary

File:tools/clang/lib/AST/InheritViz.cpp
Warning:line 94, column 42
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -triple x86_64-pc-linux-gnu -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name InheritViz.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -analyzer-config-compatibility-mode=true -mrelocation-model pic -pic-level 2 -mthread-model posix -mframe-pointer=none -relaxed-aliasing -fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables -fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb -ffunction-sections -fdata-sections -resource-dir /usr/lib/llvm-10/lib/clang/10.0.0 -D CLANG_VENDOR="Debian " -D _DEBUG -D _GNU_SOURCE -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D __STDC_LIMIT_MACROS -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST -I /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/include -I /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/include -I /build/llvm-toolchain-snapshot-10~svn373517/include -U NDEBUG -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/x86_64-linux-gnu/c++/6.3.0 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/6.3.0/../../../../include/c++/6.3.0/backward -internal-isystem /usr/local/include -internal-isystem /usr/lib/llvm-10/lib/clang/10.0.0/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-maybe-uninitialized -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir /build/llvm-toolchain-snapshot-10~svn373517/build-llvm/tools/clang/lib/AST -fdebug-prefix-map=/build/llvm-toolchain-snapshot-10~svn373517=. -ferror-limit 19 -fmessage-length 0 -fvisibility-inlines-hidden -stack-protector 2 -fobjc-runtime=gcc -fno-common -fdiagnostics-show-option -vectorize-loops -vectorize-slp -analyzer-output=html -analyzer-config stable-report-filename=true -faddrsig -o /tmp/scan-build-2019-10-02-234743-9763-1 -x c++ /build/llvm-toolchain-snapshot-10~svn373517/tools/clang/lib/AST/InheritViz.cpp
1//===- InheritViz.cpp - Graphviz visualization for inheritance --*- C++ -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file implements CXXRecordDecl::viewInheritance, which
10// generates a GraphViz DOT file that depicts the class inheritance
11// diagram and then calls Graphviz/dot+gv on it.
12//
13//===----------------------------------------------------------------------===//
14
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/Decl.h"
17#include "clang/AST/DeclCXX.h"
18#include "clang/AST/TypeOrdering.h"
19#include "llvm/Support/FileSystem.h"
20#include "llvm/Support/GraphWriter.h"
21#include "llvm/Support/raw_ostream.h"
22#include <map>
23#include <set>
24using namespace clang;
25
26namespace {
27/// InheritanceHierarchyWriter - Helper class that writes out a
28/// GraphViz file that diagrams the inheritance hierarchy starting at
29/// a given C++ class type. Note that we do not use LLVM's
30/// GraphWriter, because the interface does not permit us to properly
31/// differentiate between uses of types as virtual bases
32/// vs. non-virtual bases.
33class InheritanceHierarchyWriter {
34 ASTContext& Context;
35 raw_ostream &Out;
36 std::map<QualType, int, QualTypeOrdering> DirectBaseCount;
37 std::set<QualType, QualTypeOrdering> KnownVirtualBases;
38
39public:
40 InheritanceHierarchyWriter(ASTContext& Context, raw_ostream& Out)
41 : Context(Context), Out(Out) { }
42
43 void WriteGraph(QualType Type) {
44 Out << "digraph \"" << llvm::DOT::EscapeString(Type.getAsString())
45 << "\" {\n";
46 WriteNode(Type, false);
3
←
Calling 'InheritanceHierarchyWriter::WriteNode'
→
47 Out << "}\n";
48 }
49
50protected:
51 /// WriteNode - Write out the description of node in the inheritance
52 /// diagram, which may be a base class or it may be the root node.
53 void WriteNode(QualType Type, bool FromVirtual);
54
55 /// WriteNodeReference - Write out a reference to the given node,
56 /// using a unique identifier for each direct base and for the
57 /// (only) virtual base.
58 raw_ostream& WriteNodeReference(QualType Type, bool FromVirtual);
59};
60} // namespace
61
62void InheritanceHierarchyWriter::WriteNode(QualType Type, bool FromVirtual) {
63 QualType CanonType = Context.getCanonicalType(Type);
64
65 if (FromVirtual
3.1
'FromVirtual' is false
) {
4
←
Taking false branch
→
66 if (KnownVirtualBases.find(CanonType) != KnownVirtualBases.end())
67 return;
68
69 // We haven't seen this virtual base before, so display it and
70 // its bases.
71 KnownVirtualBases.insert(CanonType);
72 }
73
74 // Declare the node itself.
75 Out << " ";
76 WriteNodeReference(Type, FromVirtual);
77
78 // Give the node a label based on the name of the class.
79 std::string TypeName = Type.getAsString();
80 Out << " [ shape=\"box\", label=\"" << llvm::DOT::EscapeString(TypeName);
81
82 // If the name of the class was a typedef or something different
83 // from the "real" class name, show the real class name in
84 // parentheses so we don't confuse ourselves.
85 if (TypeName != CanonType.getAsString()) {
5
←
Taking true branch
→
86 Out << "\\n(" << CanonType.getAsString() << ")";
87 }
88
89 // Finished describing the node.
90 Out << " \"];\n";
91
92 // Display the base classes.
93 const CXXRecordDecl *Decl
94 = static_cast<const CXXRecordDecl *>(Type->getAs<RecordType>()->getDecl());
6
←
Assuming the object is not a 'RecordType'
→
7
←
Called C++ object pointer is null
95 for (const auto &Base : Decl->bases()) {
96 QualType CanonBaseType = Context.getCanonicalType(Base.getType());
97
98 // If this is not virtual inheritance, bump the direct base
99 // count for the type.
100 if (!Base.isVirtual())
101 ++DirectBaseCount[CanonBaseType];
102
103 // Write out the node (if we need to).
104 WriteNode(Base.getType(), Base.isVirtual());
105
106 // Write out the edge.
107 Out << " ";
108 WriteNodeReference(Type, FromVirtual);
109 Out << " -> ";
110 WriteNodeReference(Base.getType(), Base.isVirtual());
111
112 // Write out edge attributes to show the kind of inheritance.
113 if (Base.isVirtual()) {
114 Out << " [ style=\"dashed\" ]";
115 }
116 Out << ";";
117 }
118}
119
120/// WriteNodeReference - Write out a reference to the given node,
121/// using a unique identifier for each direct base and for the
122/// (only) virtual base.
123raw_ostream&
124InheritanceHierarchyWriter::WriteNodeReference(QualType Type,
125 bool FromVirtual) {
126 QualType CanonType = Context.getCanonicalType(Type);
127
128 Out << "Class_" << CanonType.getAsOpaquePtr();
129 if (!FromVirtual)
130 Out << "_" << DirectBaseCount[CanonType];
131 return Out;
132}
133
134/// viewInheritance - Display the inheritance hierarchy of this C++
135/// class using GraphViz.
136void CXXRecordDecl::viewInheritance(ASTContext& Context) const {
137 QualType Self = Context.getTypeDeclType(this);
138
139 int FD;
140 SmallString<128> Filename;
141 if (std::error_code EC = llvm::sys::fs::createTemporaryFile(
1
Taking false branch
→
142 Self.getAsString(), "dot", FD, Filename)) {
143 llvm::errs() << "Error: " << EC.message() << "\n";
144 return;
145 }
146
147 llvm::errs() << "Writing '" << Filename << "'... ";
148
149 llvm::raw_fd_ostream O(FD, true);
150
151 InheritanceHierarchyWriter Writer(Context, O);
152 Writer.WriteGraph(Self);
2
←
Calling 'InheritanceHierarchyWriter::WriteGraph'
→
153 llvm::errs() << " done. \n";
154
155 O.close();
156
157 // Display the graph
158 DisplayGraph(Filename);
159}