使用 clang AST 匹配器匹配私有 class 成员

Question

我正在编写一个 Clang 工具来静态分析源文件，并匹配和重命名 class.

的所有私有成员

考虑一个例子：

class AClass { // problem: my matcher modifies AST node here too
private:
    int a; // <- I know how to rename this 'a' using other matcher
public:
    AClass() {
        AClass cl;
        this->a = 1; // <- rename this 'a'
        cl.a = 2; // <- rename this 'a'
    }
};
void bar(AClass);
void foo() {
    //bar(AClass());
}

我使用以下匹配器来访问我想要修改的 AST 节点。效果如我所料。

clang-query> match memberExpr(hasDeclaration(namedDecl(isPrivate())))

Match #1:

sum.cpp:7:9: note: "root" binds here
    this->a = 1;
    ^~~~~~~

Match #2:

sum.cpp:8:9: note: "root" binds here
    cl.a = 2;
    ^~~~
2 matches.

如果在示例中我取消注释 bar(AClass()); 行，就会出现问题。多了一个匹配项，恰好

Match #3:

sum.cpp:1:7: note: "root" binds here
class AClass {
^~~~~~
3 matches.

这导致以一种奇怪的方式重写 class AClass 声明。我想摆脱这场比赛。

匹配器 returns 指向 MemberExpr 对象的指针。我试图通过检查 isArrow() 谓词来过滤第三个匹配项，它有所帮助，但后来我无法将表达式与点匹配，例如 cl.a.

我正在寻找其他 AST 匹配器表达式或一些对 MemberExpr 对象进行操作的代码，并访问源文件中的所有私有变量，仅此而已。

Answer 1

正如您所观察到的，问题是由于隐式定义的副本造成的构造函数。这是 AST 的转储，

% clang-check -ast-dump -ast-dump-filter=AClass s.cpp --
Dumping AClass:
CXXRecordDecl 0x2cb3700 </tmp/s.cpp:1:1, line:10:1> line:1:7 referenced class AClass definition
|-CXXRecordDecl 0x2cb3810 <col:1, col:7> col:7 implicit referenced class AClass
|-AccessSpecDecl 0x2cb38a0 <line:2:1, col:8> col:1 private
|-FieldDecl 0x2cb38e0 <line:3:3, col:7> col:7 referenced a 'int'
|-AccessSpecDecl 0x2cb3930 <line:4:1, col:7> col:1 public
|-CXXConstructorDecl 0x2cfaee0 <line:5:3, line:9:3> line:5:3 used AClass 'void (void)'
| `-CompoundStmt 0x2cfb440 <col:12, line:9:3>
|   |-DeclStmt 0x2cfb240 <line:6:5, col:14>
|   | `-VarDecl 0x2cfafe0 <col:5, col:12> col:12 used cl 'class AClass' callinit
|   |   `-CXXConstructExpr 0x2cfb210 <col:12> 'class AClass' 'void (void)'
|   |-BinaryOperator 0x2cfb2c0 <line:7:5, col:15> 'int' lvalue '='
|   | |-MemberExpr 0x2cfb270 <col:5, col:11> 'int' lvalue ->a 0x2cb38e0
|   | | `-CXXThisExpr 0x2cfb258 <col:5> 'class AClass *' this
|   | `-IntegerLiteral 0x2cfb2a0 <col:15> 'int' 1
|   `-BinaryOperator 0x2cfb360 <line:8:5, col:12> 'int' lvalue '='
|     |-MemberExpr 0x2cfb310 <col:5, col:8> 'int' lvalue .a 0x2cb38e0
|     | `-DeclRefExpr 0x2cfb2e8 <col:5> 'class AClass' lvalue Var 0x2cfafe0 'cl' 'class AClass'
|     `-IntegerLiteral 0x2cfb340 <col:12> 'int' 2
|-CXXConstructorDecl 0x2cfb070 <line:1:7> col:7 implicit used AClass 'void (const class AClass &) throw()' inline
| |-ParmVarDecl 0x2cfb1b0 <col:7> col:7 used 'const class AClass &'
| |-CXXCtorInitializer Field 0x2cb38e0 'a' 'int'
| | `-ImplicitCastExpr 0x2cfb9e0 <col:7> 'int' <LValueToRValue>
| |   `-MemberExpr 0x2cfb998 <col:7> 'const int' lvalue .a 0x2cb38e0
| |     `-DeclRefExpr 0x2cfb970 <col:7> 'const class AClass' lvalue ParmVar 0x2cfb1b0 '' 'const class AClass &'
| `-CompoundStmt 0x2cfba28 <col:7>
`-CXXDestructorDecl 0x2cfb770 <col:7> col:7 implicit used ~AClass 'void (void) throw()' inline
  `-CompoundStmt 0x2cfb890 <col:7>

其中复制构造函数在 <line:1:7> 处分配了一个定义。这里的 MemberExpr 你不小心匹配到了隐式副本中构造函数。就像理查德科恩在他的评论中写的那样， MemberExpr 不是隐含的，但它的祖先，复制构造函数。您可以删除这些不需要的像建议的那样通过过滤包含的内容进行匹配，

match memberExpr(hasDeclaration(namedDecl(isPrivate())),
                 unless(hasAncestor(isImplicit())))

这会让您找到想要的比赛，

Match #1:

/tmp/s.cpp:7:5: note: "root" binds here
    this->a = 1; // <- rename this 'a'
    ^~~~~~~

Match #2:

/tmp/s.cpp:8:5: note: "root" binds here
    cl.a = 2;    // <- rename this 'a'
    ^~~~
2 matches.

使用 clang AST 匹配器匹配私有 class 成员

Matching private class members using clang AST Matcher

c++

static-analysis

clang

abstract-syntax-tree