From f74318491134356a19ba2d9673f89c8b74ff3692 Mon Sep 17 00:00:00 2001
From: Kadir Cetinkaya <kadircet@google.com>
Date: Wed, 3 Feb 2021 12:45:46 +0100
Subject: [PATCH] [clang][CodeComplete] Fix crash on ParenListExprs

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

Differential Revision: https://reviews.llvm.org/D95935
---
 clang/lib/Sema/SemaCodeComplete.cpp            | 18 ++++++++++++++++--
 .../test/CodeCompletion/function-overloads.cpp |  6 ++++++
 clang/test/CodeCompletion/member-access.c      |  7 +++++++
 clang/unittests/Sema/CodeCompleteTest.cpp      |  1 +
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index ece204c001e7..2f5a28e132b3 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -5186,6 +5186,15 @@ void Sema::CodeCompleteMemberReferenceExpr(Scope *S, Expr *Base,
   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;
@@ -5615,12 +5624,17 @@ ProduceSignatureHelp(Sema &SemaRef, Scope *S,
 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
diff --git a/clang/test/CodeCompletion/function-overloads.cpp b/clang/test/CodeCompletion/function-overloads.cpp
index 11c864c28107..7b8ccef1d580 100644
--- a/clang/test/CodeCompletion/function-overloads.cpp
+++ b/clang/test/CodeCompletion/function-overloads.cpp
@@ -21,6 +21,8 @@ namespace NS {
 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
@@ -31,6 +33,10 @@ void test_adl() {
 // 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(
diff --git a/clang/test/CodeCompletion/member-access.c b/clang/test/CodeCompletion/member-access.c
index 72afbf2ff947..545349f71731 100644
--- a/clang/test/CodeCompletion/member-access.c
+++ b/clang/test/CodeCompletion/member-access.c
@@ -29,3 +29,10 @@ void test3(struct Point2 *p) {
 
 // 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
diff --git a/clang/unittests/Sema/CodeCompleteTest.cpp b/clang/unittests/Sema/CodeCompleteTest.cpp
index d8b303d77bb9..dae0793658c5 100644
--- a/clang/unittests/Sema/CodeCompleteTest.cpp
+++ b/clang/unittests/Sema/CodeCompleteTest.cpp
@@ -488,6 +488,7 @@ TEST(PreferredTypeTest, NoCrashOnInvalidTypes) {
     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"));
 }