> On Apr 24, 2020, at 2:44 PM, Richard Smith via cfe-users > <cfe-users@lists.llvm.org> wrote: > > On Tue, 21 Apr 2020 at 05:41, Dr S3curity via cfe-users > <cfe-users@lists.llvm.org <mailto:cfe-users@lists.llvm.org>> wrote: > Hi, > > Imagine the very basic code below, it has some missing elements, we dont have > the foo() function and MyClass class, > > ```test.cpp > int main(int argc, char *argv[]) > { > MyClass* mc = new MyClass(); > mc.get_count(); > foo(1, 2, 3); > std::cout << "this is a test" << endl; > } > ``` > > How can I get AST for that code? > I tried `clang -Xclang -ast-dump -fsyntax-only test.cpp`, I can get the AST > tree but without MyClass and foo() function, it doesn't even say foo is a > function with 3 integer parameters.
I am not really familiar with -frecovery-ast but since even such relatively simple C++ snippet is ambivalent I am not sure clang can actually answer your questions completely :( It would have to "know" things like the following before it could tell you what "foo" or "MyClass" are. - Can't foo be a global object of class with call operator accepting 3 int-s? - Do the parameters actually need to be int-s or just any types that have implicit conversions from int? - Can't MyClass be a typedef? - Can't macros be involved? - Can't the code actually be semantically incorrect? > This can be problematic for different cases for example IDE's where you dont > have all the project dependencies but yet you need to know what are the > elements in your code. > > Is that possible to do with libclang? Any other suggestions are welcome. > > You can request that more invalid portions of the AST are retained by using > `-Xclang -frecovery-ast`. In this case, that will preserve the function call > expression as a RecoveryExpr. For now at least, we don't have the ability to > preserve AST information for the invalid "new MyClass" nor the expression > using of undeclared "std::cout" and "endl", but -frecovery-ast is expected to > improve over time to retain more such AST nodes. (And perhaps eventually it > will be enabled by default, at which point the flag for it might disappear. > We don't guarantee any forward compatibility with -Xclang flags.) IIUC you'd still have to decide what you think the RecoveryExpr AST node actually is - it could be a CXXMemberCallExpr if it's a call operator or just a CallExpr if foo is a free function. > _______________________________________________ > cfe-users mailing list > cfe-users@lists.llvm.org <mailto:cfe-users@lists.llvm.org> > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users > <https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-users>
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