gribozavr2 added a comment.
In D80603#2058019 <https://reviews.llvm.org/D80603#2058019>, @aaron.ballman
wrote:
> I'm sorry if I'm being dense, but `hasParameter` traverses to the
> `ParmVarDecl`, so I'm not certain I understand why this new matcher is needed
> as a public matcher. It seems like you can already accomplish this without
> adding a second API to do effectively the same thing:
> `functionDecl(hasParameter(0, parmVarDecl().bind("param")))`, can't you?
It is syntax sugar, true. Note that the proposed matcher is a narrowing matcher
for `parmVarDecl()`, while your suggestion is a narrowing matcher for
`functionDecl()`, so it is not an entirely apples-to-apples comparison. Think
about use cases like: `declRefExpr(to(parmVarDecl(at(...))))`. To rewrite that
with `hasParameter()`, we have to use `hasAncestor` to find the `functionDecl`
first, and then compare the AST node pointers. So while it is possible to
express this proposed operation today, it requires a complex matcher for such a
conceptually simple operation.
================
Comment at: clang/include/clang/ASTMatchers/ASTMatchers.h:4621
+template <typename DeclT>
+static bool __isParamAt(const clang::DeclContext *Context,
+ const clang::ParmVarDecl &Node, unsigned N) {
----------------
Identifiers with double underscores are reserved. Also, this file typically
does not define helpers.
My best suggestion is to define a local lambda in the AST_MATCHER_P, or just
copy the code three times -- there is not that much duplication.
Repository:
rG LLVM Github Monorepo
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https://reviews.llvm.org/D80603/new/
https://reviews.llvm.org/D80603
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