[PATCH] D88403: Migrate Declarators to use the List API

[Eduardo Caldas via Phabricator via cfe-commits]

eduucaldas marked 3 inline comments as done.
eduucaldas added inline comments.


================
Comment at: clang/unittests/Tooling/Syntax/BuildTreeTest.cpp:2932
   |-'void'
-  |-SimpleDeclarator Declarator
-  | |-'foo'
-  | `-ParametersAndQualifiers
-  |   |-'(' OpenParen
-  |   `-')' CloseParen
+  |-DeclaratorList Declarators
+  | `-SimpleDeclarator ListElement
----------------
gribozavr2 wrote:
> eduucaldas wrote:
> > This sounds weird and is probably the reason why SO many tests failed.
> > 
> > According to the [[ https://eel.is/c++draft/dcl.fct.def.general#nt:function-definition | grammar ]] a function definition/declaration might only have one declarator:
> > ```
> > function-definition:
> > attribute-specifier-seq_opt decl-specifier-seq_opt declarator virt-specifier-seq_opt function-body
> > ...
> > ```
> > But our implementation calls `processDeclaratorAndDeclaration` for `DeclaratorDecl`, which englobes `FunctionDecl`.
> > 
> > I also noticed that we seem to have quite extensive support for declarations even rarer ones:
> > `StaticAssertDeclaration`, `LinkageSpecificationDeclaration` ... Moreover, their names and definitions seem to adequately follow the grammar. However we don't have a `FunctionDefinition` as defined in the grammar. Was grouping `FunctionDefintion` and `FunctionDeclaration` as `SimpleDeclaration`  a conscious choice? (I looked quickly at commits that added `processDeclaratorAndDeclaration` but couldn't find any clue)
> It seemed reasonable for uniformity. However, I can definitely see an argument for defining a special kind of tree node for them, especially now that if we use SimpleDeclaration for functions we would always get a 1-element list wrapper.
> 
> On the other hand, the following is a valid declaration:
> 
> ```
> int x, f(int);
> ```
> 
> Wouldn't it be weird if function definitions and declarations were modeled differently? I understand they are different in the C++ grammar, but I think it would be at least a bit surprising for users.
Oh my god... that hurts my eyes...

I don't know what is more weird to be fair. In my view unifying both seems like a similar decision as unifying expressions and statements under the same ClangAST node because:
1. I think they have other syntactic differences.
2. I think generally people see declarations and definitions as different things. Whereas having a list in the definition of a function is completely unexpected.

Looking back at the grammar for declarations I think we would also benefit of trying to simplify it before mapping it to syntax trees. Although I would love to do that, I'm afraid there's too much on my plate already.

Should I leave a `FIXME` regarding this and adapt the other tests? Or do you wanna discuss this more deeply? Both options are fine for me :)


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https://reviews.llvm.org/D88403