[PATCH] D158808: [Clang] Modify Parser::ParseLambdaExpressionAfterIntroducer to check whether the lambda-declarator is valid

[Shafik Yaghmour via Phabricator via cfe-commits]

shafik created this revision.
shafik added reviewers: cor3ntin, aaron.ballman, erichkeane, rsmith.
Herald added a project: All.
shafik requested review of this revision.

We had a couple of crashes due to invalid lambda trailing return types that were diagnosed but not treated as errors during parsing. So now in `Parser::ParseLambdaExpressionAfterIntroducer(...)` after `ActOnStartOfLambdaDefinition(...)` we also check if the lambda-declarator is invalid and if so we end up in `ActOnLambdaError(...)`.

Fixes:

https://github.com/llvm/llvm-project/issues/64962
https://github.com/llvm/llvm-project/issues/28679


https://reviews.llvm.org/D158808

Files:
  clang/lib/Parse/ParseExprCXX.cpp
  clang/test/Parser/cxx0x-lambda-expressions.cpp
  clang/test/SemaCXX/subst-func-type-invalid-ret-type.cpp


Index: clang/test/SemaCXX/subst-func-type-invalid-ret-type.cpp
===================================================================
--- clang/test/SemaCXX/subst-func-type-invalid-ret-type.cpp
+++ clang/test/SemaCXX/subst-func-type-invalid-ret-type.cpp
@@ -5,12 +5,11 @@
 template<typename T> T declval();
 
 template <typename T>
-auto Call(T x) -> decltype(declval<T>()(0)) {} // expected-note{{candidate template ignored}}
+auto Call(T x) -> decltype(declval<T>()(0)) {}
 
 class Status {};
 
 void fun() {
   // The Status() (instead of Status) here used to cause a crash.
   Call([](auto x) -> Status() {}); // expected-error{{function cannot return function type 'Status ()}}
-  // expected-error at -1{{no matching function for call to 'Call'}}
 }
Index: clang/test/Parser/cxx0x-lambda-expressions.cpp
===================================================================
--- clang/test/Parser/cxx0x-lambda-expressions.cpp
+++ clang/test/Parser/cxx0x-lambda-expressions.cpp
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++11 -Wno-c99-designator %s
+// RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -Wno-c++20-extensions -std=c++11 -Wno-c99-designator %s
 // RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++20 -Wno-c99-designator %s
 // RUN: %clang_cc1 -fsyntax-only -Wno-unused-value -verify -std=c++23 -Wno-c99-designator %s
 
@@ -181,3 +181,11 @@
   template <typename T>
   void m_fn1(T x = 0[0); // expected-error{{expected ']'}} expected-note{{to match this '['}}
 } *U;
+
+namespace GH64962 {
+void f() {
+  [] <typename T>(T i) -> int[] // expected-error {{function cannot return array type 'int[]'}}
+                                // extension-warning {{explicit template parameter list for lambdas is a C++20 extension}}
+    { return 3; } (v); // expected-error {{use of undeclared identifier 'v'}}
+}
+}
Index: clang/lib/Parse/ParseExprCXX.cpp
===================================================================
--- clang/lib/Parse/ParseExprCXX.cpp
+++ clang/lib/Parse/ParseExprCXX.cpp
@@ -1546,7 +1546,7 @@
   TemplateParamScope.Exit();
   LambdaScope.Exit();
 
-  if (!Stmt.isInvalid() && !TrailingReturnType.isInvalid())
+  if (!Stmt.isInvalid() && !TrailingReturnType.isInvalid() && !D.isInvalidType())
     return Actions.ActOnLambdaExpr(LambdaBeginLoc, Stmt.get(), getCurScope());
 
   Actions.ActOnLambdaError(LambdaBeginLoc, getCurScope());


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