2 files changed, 29 insertions, 1 deletions
diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 8fbe7833a1f..2e30c52df93 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -5281,7 +5281,8 @@ void Parser::ParseFunctionDeclarator(Declarator &D,
 
       // Parse exception-specification[opt].
       bool Delayed = D.isFirstDeclarationOfMember() &&
-                     D.isFunctionDeclaratorAFunctionDeclaration();
+                     D.isFunctionDeclaratorAFunctionDeclaration() &&
+                     !Actions.isLibstdcxxEagerExceptionSpecHack(D);
       ESpecType = tryParseExceptionSpecification(Delayed,
                                                  ESpecRange,
                                                  DynamicExceptions,
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index c35de6b8eda..7175c016734 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -35,6 +35,33 @@ static const FunctionProtoType *GetUnderlyingFunction(QualType T)
   return T->getAs<FunctionProtoType>();
 }
 
+/// HACK: libstdc++ has a bug where it shadows std::swap with a member
+/// swap function then tries to call std::swap unqualified from the exception
+/// specification of that function. This function detects whether we're in
+/// such a case and turns off delay-parsing of exception specifications.
+bool Sema::isLibstdcxxEagerExceptionSpecHack(const Declarator &D) {
+  auto *RD = dyn_cast<CXXRecordDecl>(CurContext);
+
+  // All the problem cases are member functions named "swap" within class
+  // templates declared directly within namespace std.
+  if (!RD || RD->getEnclosingNamespaceContext() != getStdNamespace() ||
+      !RD->getIdentifier() || !RD->getDescribedClassTemplate() ||
+      !D.getIdentifier() || !D.getIdentifier()->isStr("swap"))
+    return false;
+
+  // Only apply this hack within a system header.
+  if (!Context.getSourceManager().isInSystemHeader(D.getLocStart()))
+    return false;
+
+  return llvm::StringSwitch<bool>(RD->getIdentifier()->getName())
+      .Case("array", true)
+      .Case("pair", true)
+      .Case("priority_queue", true)
+      .Case("stack", true)
+      .Case("queue", true)
+      .Default(false);
+}
+
 /// CheckSpecifiedExceptionType - Check if the given type is valid in an
 /// exception specification. Incomplete types, or pointers to incomplete types
 /// other than void are not allowed.