[PATCH] D98433: [clang] [C++2b] [P1102] Accept lambdas without parameter list ().

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added inline comments.


================
Comment at: clang/lib/Parse/ParseExprCXX.cpp:1438
 
-    // Parse trailing-return-type[opt].
-    if (Tok.is(tok::arrow)) {
-      FunLocalRangeEnd = Tok.getLocation();
-      SourceRange Range;
-      TrailingReturnType =
-          ParseTrailingReturnType(Range, /*MayBeFollowedByDirectInit*/ false);
-      TrailingReturnTypeLoc = Range.getBegin();
-      if (Range.getEnd().isValid())
-        DeclEndLoc = Range.getEnd();
-    }
+    PrototypeScope.Exit();
+  } else if (getLangOpts().CPlusPlus2b) {
----------------
No need to call this here, it happens from the destructor of `ParseScope`.


================
Comment at: clang/lib/Parse/ParseExprCXX.cpp:1440
+  } else if (getLangOpts().CPlusPlus2b) {
+    ParseScope PrototypeScope(this, Scope::FunctionPrototypeScope |
+                                        Scope::FunctionDeclarationScope |
----------------
I don't know the answer to this, but... do we need a prototype scope at all when there's no parameter list? The old code was doing this, so I don't think this is an issue with your patch per se, more just curiosity whether this is necessary in this case.


================
Comment at: clang/lib/Parse/ParseExprCXX.cpp:1447
+    std::vector<DeclaratorChunk::ParamInfo> EmptyParamInfo;
+    ParseLambdaSpecifiers(/*LParenLoc=*/NoLoc, /*RParenLoc=*/NoLoc,
+                          EmptyParamInfo, /*EllipsisLoc=*/NoLoc);
----------------
curdeius wrote:
> I'm not sure what I should do with `LParenLoc` and `RParenLoc`. Any idea?
What you've done here seems reasonable to me. The `SourceLocation` for the parens will be invalid, which is the behavior I'd expect when the parens are missing.


================
Comment at: clang/lib/Parse/ParseExprCXX.cpp:1450
 
     PrototypeScope.Exit();
   } else if (Tok.isOneOf(tok::kw_mutable, tok::arrow, tok::kw___attribute,
----------------
No need to call this here, it happens from the destructor of `ParseScope`.


================
Comment at: clang/test/Parser/cxx2b-lambdas.cpp:22
+auto XL1 = [] constexpr mutable constexpr {};  // expected-error{{cannot appear multiple times}}
+auto XL2 = []) constexpr mutable constexpr {}; // expected-error{{expected body}}
----------------
It'd be handy to test: `auto XL3 = []( constexpr mutable constexpr {}; ` where the parameter list is missing the closing right paren.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D98433/new/

https://reviews.llvm.org/D98433