[clang][CodeComplete] Fix crash on ParenListExprs

[kadircet]

• Also handle memberrefexpr case.

Fixes https://github.com/clangd/clangd/issues/676.

[kadircet]

ping

[hokein]

clang/lib/Sema/SemaCodeComplete.cpp

5191

mention that why we specialize ParentListExpr -- ParenListExprs don't have a predefined type

I think we won't (hopefully) have a 0-children ParenListExpr.

[kadircet]

• Update comments

clang/lib/Sema/SemaCodeComplete.cpp

 void Sema::CodeCompleteMemberReferenceExpr(Scope *S, Expr *Base,
                                            Expr *OtherOpBase,
                                            SourceLocation OpLoc, bool IsArrow,
                                            bool IsBaseExprStatement,
                                            QualType PreferredType) {
   if (!Base || !CodeCompleter)
     return;
 
+  // Peel off the ParenListExpr by chosing the last one, as they don't have a
+  // predefined type.
+  if (auto *PLE = llvm::dyn_cast<ParenListExpr>(Base))
+    Base = PLE->getExpr(PLE->getNumExprs() - 1);
+  if (OtherOpBase) {
+    if (auto *PLE = llvm::dyn_cast<ParenListExpr>(OtherOpBase))
+      OtherOpBase = PLE->getExpr(PLE->getNumExprs() - 1);
+  }
+
   ExprResult ConvertedBase = PerformMemberExprBaseConversion(Base, IsArrow);
   if (ConvertedBase.isInvalid())
     return;
   QualType ConvertedBaseType = ConvertedBase.get()->getType();
 
   enum CodeCompletionContext::Kind contextKind;
 
   if (IsArrow) {
ProduceSignatureHelp(Sema &SemaRef, Scope *S,
   SemaRef.CodeCompleter->ProcessOverloadCandidates(
       SemaRef, CurrentArg, Candidates.data(), Candidates.size(), OpenParLoc);
   return getParamType(SemaRef, Candidates, CurrentArg);
 }
 
 QualType Sema::ProduceCallSignatureHelp(Scope *S, Expr *Fn,
                                         ArrayRef<Expr *> Args,
                                         SourceLocation OpenParLoc) {
-  if (!CodeCompleter)
+  if (!CodeCompleter || !Fn)
     return QualType();
 
+  // If we have a ParenListExpr for LHS, peel it off by chosing the last expr.
+  // As ParenListExprs don't have a predefined type.
+  if (auto *PLE = llvm::dyn_cast<ParenListExpr>(Fn))
+    Fn = PLE->getExpr(PLE->getNumExprs() - 1);
+
   // FIXME: Provide support for variadic template functions.
   // Ignore type-dependent call expressions entirely.
-  if (!Fn || Fn->isTypeDependent() || anyNullArguments(Args))
+  if (Fn->isTypeDependent() || anyNullArguments(Args))
     return QualType();
   // In presence of dependent args we surface all possible signatures using the
   // non-dependent args in the prefix. Afterwards we do a post filtering to make
   // sure provided candidates satisfy parameter count restrictions.
   auto ArgsWithoutDependentTypes =
       Args.take_while([](Expr *Arg) { return !Arg->isTypeDependent(); });
 
   SmallVector<ResultCandidate, 8> Results;

clang/test/CodeCompletion/function-overloads.cpp

namespace NS {
   struct Y { Y(X); };
   template <class T = int>
   void g(X, Y);
 }
 
 void test_adl() {
   NS::X x;
   g(x, x);
+  (void)(f)(1, 2, 3);
+  (void)(test, test, test, f)(1, 2, 3);
 }
 
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:9 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:10 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:17 %s -o - | FileCheck -check-prefix=CHECK-CC2 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:19 %s -o - | FileCheck -check-prefix=CHECK-CC2 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:20 %s -o - | FileCheck -check-prefix=CHECK-CC3 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:10:21 %s -o - | FileCheck -check-prefix=CHECK-CC4 %s
 // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:23:7 %s -o - | \
 // RUN:    FileCheck -check-prefix=CHECK-CC5 %s
+// RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:24:13 %s -o - | \
+// RUN:    FileCheck -check-prefix=CHECK-CC1 %s
+// RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:25:31 %s -o - | \
+// RUN:    FileCheck -check-prefix=CHECK-CC1 %s
 // CHECK-CC1: OVERLOAD: [#int#]f(<#float x#>, float y)
 // CHECK-CC1: OVERLOAD: [#int#]f(<#int i#>)
 // CHECK-CC1-NOT, CHECK-CC2-NOT: OVERLOAD: A(
 // CHECK-CC2: OVERLOAD: [#int#]f(float x, float y)
 // CHECK-CC2-NOT: OVERLOAD: [#int#]f(int i)
 // CHECK-CC3: OVERLOAD: A(<#int#>, int, int)
 // CHECK-CC3: OVERLOAD: A(<#const A &#>)
 // CHECK-CC3: OVERLOAD: A(<#A &&#>)
 // CHECK-CC4: OVERLOAD: A(int, <#int#>, int)
 // CHECK-CC5: OVERLOAD: [#void#]g(X, <#Y#>)

clang/test/CodeCompletion/member-access.c

void test3(struct Point2 *p) {
   p.
 }
 
 // RUN: %clang_cc1 -fsyntax-only -code-completion-with-fixits -code-completion-at=%s:20:6 %s -o - | FileCheck -check-prefix=CHECK-CC2 %s
 // CHECK-CC2: x (requires fix-it: {20:4-20:6} to ".")
 
 // RUN: %clang_cc1 -fsyntax-only -code-completion-with-fixits -code-completion-at=%s:24:5 %s -o - | FileCheck -check-prefix=CHECK-CC3 %s
 // CHECK-CC3: x (requires fix-it: {24:4-24:5} to "->")
+
+void test4(struct Point *p) {
+  (int)(p)->x;
+  (int)(0,1,2,3,4,p)->x;
+}
+// RUN: %clang_cc1 -fsyntax-only -code-completion-with-fixits -code-completion-at=%s:34:13 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s
+// RUN: %clang_cc1 -fsyntax-only -code-completion-with-fixits -code-completion-at=%s:35:23 %s -o - | FileCheck -check-prefix=CHECK-CC1 %s

clang/unittests/Sema/CodeCompleteTest.cpp

 }
 
 TEST(PreferredTypeTest, NoCrashOnInvalidTypes) {
   StringRef Code = R"cpp(
     auto x = decltype(&1)(^);
     auto y = new decltype(&1)(^);
     // GNU decimal type extension is not supported in clang.
     auto z = new _Decimal128(^);
+    void foo() { (void)(foo)(^); }
   )cpp";
   EXPECT_THAT(collectPreferredTypes(Code), Each("NULL TYPE"));
 }
 
 } // namespace