Merge pull request #77346 from mikeash/demangler-nul-terminator

[Demangler] Accept overly short type names if they are NUL terminated

lib/Demangling/Demangler.cpp

@@ -804,6 +804,12 @@ NodePointer Demangler::demangleType(StringRef MangledName,
 bool Demangler::parseAndPushNodes() {
   const auto textSize = Text.size();
   while (Pos < textSize) {
+    // Programs may look up a type by NUL-terminated name with an excessive
+    // length. Keep them working by returning success if we encounter a NUL in
+    // the middle of the string where an operator is expected.
+    if (peekChar() == '\0')
+      return true;
+
     NodePointer Node = demangleOperator();
     if (!Node)
       return false;

test/Runtime/demangleToMetadata.swift

@@ -566,5 +566,17 @@ if #available(SwiftStdlib 6.0, *) {
   }
 }
 
+if #available(SwiftStdlib 6.1, *) {
+  DemangleToMetadataTests.test("NUL-terminated name, excessive length value") {
+    let t = _getTypeByMangledNameInContext("4main1SV", 256,
+                                           genericContext: nil,
+                                           genericArguments: nil)
+    expectNotNil(t)
+    if let t {
+      expectEqual(type(of: S()), t)
+    }
+  }
+}
+
 runAllTests()