From: Erik Pilkington <erik.pilkington@gmail.com>
Date: Mon, 12 Aug 2019 18:31:27 +0000 (+0000)
Subject: [Sema] Require a complete type for __builtin_bit_cast operands
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=da111020da768635d3636091d9e61de15486ab92;p=clang

[Sema] Require a complete type for __builtin_bit_cast operands

Fixes llvm.org/PR42936

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@368600 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Sema/SemaCast.cpp b/lib/Sema/SemaCast.cpp
index f184eda2f2..7a1d52ad4e 100644
--- a/lib/Sema/SemaCast.cpp
+++ b/lib/Sema/SemaCast.cpp
@@ -2803,6 +2803,14 @@ void CastOperation::CheckBuiltinBitCast() {
     SrcExpr = Self.CreateMaterializeTemporaryExpr(SrcType, SrcExpr.get(),
                                                   /*IsLValueReference=*/false);
 
+  if (Self.RequireCompleteType(OpRange.getBegin(), DestType,
+                               diag::err_typecheck_cast_to_incomplete) ||
+      Self.RequireCompleteType(OpRange.getBegin(), SrcType,
+                               diag::err_incomplete_type)) {
+    SrcExpr = ExprError();
+    return;
+  }
+
   CharUnits DestSize = Self.Context.getTypeSizeInChars(DestType);
   CharUnits SourceSize = Self.Context.getTypeSizeInChars(SrcType);
   if (DestSize != SourceSize) {
diff --git a/test/SemaCXX/builtin-bit-cast.cpp b/test/SemaCXX/builtin-bit-cast.cpp
index 3dddadc561..87919d9d9d 100644
--- a/test/SemaCXX/builtin-bit-cast.cpp
+++ b/test/SemaCXX/builtin-bit-cast.cpp
@@ -37,3 +37,12 @@ constexpr unsigned long ul = __builtin_bit_cast(unsigned long, not_trivially_cop
 
 // expected-error@+1 {{__builtin_bit_cast destination type must be trivially copyable}}
 constexpr long us = __builtin_bit_cast(unsigned long &, 0L);
+
+namespace PR42936 {
+template <class T> struct S { int m; };
+
+extern S<int> extern_decl;
+
+int x = __builtin_bit_cast(int, extern_decl);
+S<char> y = __builtin_bit_cast(S<char>, 0);
+}