[PATCH] D57267: [AST] Factor out the logic of the various Expr::Ignore*

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: lib/AST/Expr.cpp:2562
+static Expr *IgnoreImpCastsSingleStep(Expr *E) {
+  if (auto *ICE = dyn_cast_or_null<ImplicitCastExpr>(E))
+    return ICE->getSubExpr();
----------------
riccibruno wrote:
> aaron.ballman wrote:
> > Do we really need to accept null arguments? We didn't previously, and this increases the overhead of something we do pretty often (though it's probably only a negligible performance hit).
> I did benchmark it to see if there is any difference but could not measure any (looking at the generated code this adds a single null check at the start). My concern was that it could be possible that some AST node has a null child, perhaps when the AST is malformed. I will however defer to you or Richard since I probably lack some of the background needed to make this choice.
If it doesn't seem to have a measurable performance impact, I think it's reasonable.


================
Comment at: lib/AST/Expr.cpp:2563
+
+  else if (auto *FE = dyn_cast_or_null<FullExpr>(E))
+    return FE->getSubExpr();
----------------
No `else` after a `return`


================
Comment at: lib/AST/Expr.cpp:2580
+
+  else if (auto *NTTP = dyn_cast_or_null<SubstNonTypeTemplateParmExpr>(E))
+    return NTTP->getReplacement();
----------------
No `else` after a `return` (same elsewhere in the patch).


================
Comment at: lib/AST/Expr.cpp:2684
+
+namespace {
+
----------------
Rather than an unnamed namespace, you should prefer static function declarations per the style guide.


================
Comment at: lib/AST/Expr.cpp:2695
+/// Note that a null E is valid; in this case nothing is done.
+template <typename... FnTys> Expr *IgnoreExprNodes(Expr *E, FnTys &&... Fns) {
   Expr *LastE = nullptr;
----------------
Formatting looks off here, did clang-format produce this?


Repository:
  rC Clang

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D57267/new/

https://reviews.llvm.org/D57267