[cfe-dev] AST-dump
Manuel Klimek
klimek at google.com
Mon Jun 10 02:35:13 PDT 2013
On Thu, May 30, 2013 at 10:41 AM, Pedro Delgado Perez
<pedro.delgado at uca.es>wrote:
> Hi,
>
> Default, copy, and move constructors are provided implicitly (under
> various conditions - obviously if you have members that aren't default,
> copy, or move constructible, you might not/cannot get all of those)
>
> Ok, but this keeps giving me trouble. I've used the isImplicit() matcher
> to avoid those implicit constructors, but it isn't working how I need yet.
>
> recordDecl(
> unless(hasMethod(constructorDecl(
> allOf(hasAnyParameter(anything()), unless(isImplicit()))
>
> I know I shouldn't use the -ast-dump-xml option, but look at this. If I
> have a class like this:
>
> class E{
> public:
> E(){int a = 3;};
> int e;
> };
>
> This is the dump of the constructor:
>
> <CXXConstructor used="1" ptr="0xd7d8070" name="E" prototype="true">
> <FunctionProtoType ptr="0xd7d8040" canonical="0xd7d8040">
> <BuiltinType ptr="0xd7d7c30" canonical="0xd7d7c30"/>
> <parameters/>
> </FunctionProtoType>
> <Stmt>
> CompoundStmt 0xd7d81a8 <./ABC.h:4:6, col:17>
> `-DeclStmt 0xd7d8198 <col:7, col:16>
> `-VarDecl 0xd7d8150 <col:7, col:15> a 'int'
> `-IntegerLiteral 0xd7d8180 <col:15> 'int' 3
>
> </Stmt>
> </CXXConstructor>
>
> And this case is working fine. But when the class is this other way:
>
> class E{
> public:
> E();
> int e;
> };
>
> E::E(){
> int a = 3;
> }
>
> The dump creates two CXXConstructors, I suppose one for the declaration
> and the other for the definition:
>
> <CXXConstructor ptr="0xc7de070" name="E" prototype="true">
> <FunctionProtoType ptr="0xc7de040" canonical="0xc7de040">
> <BuiltinType ptr="0xc7ddc30" canonical="0xc7ddc30"/>
> <parameters/>
> </FunctionProtoType>
> </CXXConstructor>
>
> ....
>
> <CXXConstructor used="1" ptr="0xc7de270" name="E" previous="0xc7de070"
> prototype="true">
> <FunctionProtoType ptr="0xc7de040" canonical="0xc7de040">
> <BuiltinType ptr="0xc7ddc30" canonical="0xc7ddc30"/>
> <parameters/>
> </FunctionProtoType>
> <Stmt>
> CompoundStmt 0xc7de378 <./ABC.h:8:7, line:10:1>
> `-DeclStmt 0xc7de368 <line:9:2, col:11>
> `-VarDecl 0xc7de320 <col:2, col:10> a 'int'
> `-IntegerLiteral 0xc7de350 <col:10> 'int' 3
>
> </Stmt>
> </CXXConstructor>
>
> And this is the case my matcher is not retrieving the class E.
>
FYI, the matcher you proposed above works fine in that example for me (I
get a match on "::E").
> I don't know if clang it's considering that first CxxConstructor as
> implicit... The only difference I can see is the "used" attribute. I've
> tried creating a simple matcher to use the isUsed() method of Decl class:
>
> namespace clang{
> namespace ast_matchers{
> AST_MATCHER(Decl, isUsed)
> {
> return Node.isUsed();
> }
> }
> }
>
> but, this is having no influence.
>
> Maybe, I'm ignoring something.
>
> Thanks,
>
> Pedro.
>
>
>
> *El dia 28 may 2013 18:18, David Blaikie <dblaikie at gmail.com> escribió:*
>
>
>
>
> On Tue, May 28, 2013 at 2:07 AM, Pedro Delgado Perez <pedro.delgado at uca.es
> > wrote:
>
> That seems like an approach that works. I don't know that there's a
> different common property. Why's the default constructor different from the
> copy constructor here?
>
> First of all, sorry but I made a mistake in the example:
>
>
> class A{
> 1. A(){...}
> 2. A(int a){...}
>
> 3. *A(const A& a){... ...}*
> };
>
> What I mean is that I need to find if there is at least one constructor
> that explicitly overloads the default constructor so that if I delete the
> default constructor the compiler won't provide the default constructor. So,
> my question was totally erroneous as the copy constructor does overload the
> default constructor if provided, but I don't want to take it into account
> if it wasn't explicitly provided.
>
> A better question is: which are the kind of constructors that the compiler
> provides if no constructors are explicitly supplied? Only the default and
> the copy constructor (in some situations)?
> Default, copy, and move constructors are provided implicitly (under
> various conditions - obviously if you have members that aren't default,
> copy, or move constructible, you might not/cannot get all of those)
>
> If "unless(allOf(... ...))" is the best solution, could someone enumerate
> the kind of constructors I must to indicate in that matcher?
>
> I'd suggest to not use ast-dump-xml any more. It's basically deprecated,
> and hopefully it'll be removed soon. -ast-dump gives you all the
> information (and more).
>
> Ok, I didn't know it.
>
> ... you can see that one is the default constructor and the other one is
> the copy constructor. If you just put "G g;" into the code instead of the
> second class, you'll also see that a simple use of G already triggers the
> copy constructor to appear. Others are probably better able to explain
> exactly when a copy constructor is created.
>
> Further information will be well received.
>
> Regards,
>
> Pedro.
> *El dia 27 may 2013 12:24, Manuel Klimek <klimek at google.com> escribió:*
> Hi Pedro,
> first, please always send those mails also to cfe-dev. There are people
> who are much more knowledgable about the AST on that list, and you'll often
> get better answers faster that way :)
> On Mon, May 27, 2013 at 10:00 AM, Pedro Delgado Perez <
> pedro.delgado at uca.es> wrote:
>
> Sorry Manuel, but I prefer to ask you all the things I don't know before
> you reply me:
>
> How do I know that a CXXConstructorDecl is a "simple" constructor of a
> class. I mean, I want to find all the constructors in a class, but not the
> copy, the move or things like this constructors. I'm not able to find this
> in the documentation. To clarify this, I'm going to put an example:
>
> class A{
> 1. A(){...}
> 2. A(int a){...}
> 3. A(const &a){... ...}
> };
>
> I want to look only for 1 and 2 and not for 3 when I ask:
> recordDecl(hasMethod(constructDecl(...)));
>
> What can I do? Do I have to write "unless(allOf(isCopyConstructor(),
> isMoveConstructor()...))" for each type of existing constructors?
> That seems like an approach that works. I don't know that there's a
> different common property. Why's the default constructor different from the
> copy constructor here?
>
>
> Thanks,
>
> Pedro.
>
>
>
> Hi Manuel,
>
> I would like to ask you something about the AST built by Clang if you
> don't mind. I've just have a look at your video of introduction to Clang
> AST (By the way, nice tutorial!) and I think that you may have an answer
> for my trouble.
>
> Look, I was trying to look for classes that had only the default
> constructor through ASTMatchers. Well, I tested my matcher with the next
> classes:
>
> class G{
> public:
> G():a(1){}
> int a;
> virtual int ma(int arg);
> };
>
> class L: *public G*{
> public:
> L(){v = 1;}
> int b;
> int h;
> virtual int ma(int arg);
> private:
> int v;
> int f();
> };
>
> My matcher only retrieved the class 'L' and not the 'G'. I was wondering
> what would be the problem when I had a look to the ast-dump-xml option:
> I'd suggest to not use ast-dump-xml any more. It's basically deprecated,
> and hopefully it'll be removed soon. -ast-dump gives you all the
> information (and more).
>
> <CXXRecord ptr="0xd695f30" name="G" typeptr="0xd695f80">
> <CXXRecord ptr="0xd695fd0" name="G" typeptr="0xd695f80"/>
> <AccessSpec ptr="0xd696020" access="public"/>
> *<CXXConstructor* used="1" ptr="0xd696080" name="G" prototype="true">
> <FunctionProtoType ptr="0xd696050" canonical="0xd696050">
> <BuiltinType ptr="0xd695c40" canonical="0xd695c40"/>
> <parameters/>
> </FunctionProtoType>
> <Stmt>
> CompoundStmt 0xd696450 <tst.cpp:7:10, col:11>
> </Stmt>
> </CXXConstructor>
>
> ....
>
> *<CXXConstructor* ptr="0xd6aefc0" name="G" prototype="true" inline="true">
> <FunctionProtoType ptr="0xd6af050" canonical="0xd6af030"
> exception_spec="unevaluated">
> <BuiltinType ptr="0xd695c40" canonical="0xd695c40"/>
> <parameters>
> <LValueReferenceType ptr="0xd696240" canonical="0xd696240">
> <QualType const="true">
> <RecordType ptr="0xd695f80" canonical="0xd695f80">
> <CXXRecord ref="0xd695f30"/>
> </RecordType>
> </QualType>
> </LValueReferenceType>
> </parameters>
> </FunctionProtoType>
> <ParmVar ptr="0xd6af070" name="" initstyle="c">
> <LValueReferenceType ptr="0xd696240" canonical="0xd696240">
> <QualType const="true">
> <RecordType ptr="0xd695f80" canonical="0xd695f80">
> <CXXRecord ref="0xd695f30"/>
> </RecordType>
> </QualType>
> </LValueReferenceType>
> </ParmVar>
> </CXXConstructor>
> </CXXRecord>
>
> Why class 'G' has two constructors? If I change the test program in order
> that class 'L' doesn't inherits from class 'G', this doesn't happen (class
> 'G' only has one constructor in the ast-dump-xml) Could you lend me a hand?
> If you look at -ast-dump:
> $ clang -cc1 -ast-dump t4.cc
> <snip>
> |-CXXRecordDecl 0x37faf80 <t4.cc:1:1, line:6:1> class G
> <snip>
> | |-CXXConstructorDecl 0x37fb1c0 <line:3:3, col:15> G 'void (void)'
> | | |-CXXCtorInitializer Field 0x37fb290 'a' 'int'
> | | | |-IntegerLiteral 0x382d018 <col:11> 'int' 1
> | | `-CompoundStmt 0x382d0a0 <col:14, col:15>
> <snip>
> | `-CXXConstructorDecl 0x382da70 <col:7> G 'void (const class G &)' inline
> | `-ParmVarDecl 0x382f820 <col:7> 'const class G &'
> <snip>
> ... you can see that one is the default constructor and the other one is
> the copy constructor. If you just put "G g;" into the code instead of the
> second class, you'll also see that a simple use of G already triggers the
> copy constructor to appear. Others are probably better able to explain
> exactly when a copy constructor is created.
> cheers,
> /Manuel
>
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