fix

Author: benpious

stdlib/public/core/KeyPath.swift

@@ -3712,7 +3712,7 @@ internal func _instantiateKeyPathBuffer(
 }
 
 @_silgen_name("swift_keypath_dladdr")
-internal func keypath_dladdr(_: UnsafeRawPointer) -> UnsafePointer<CChar>
+internal func keypath_dladdr(_: UnsafeRawPointer) -> UnsafePointer<CChar>?
 
 @_silgen_name("swift_keypathSourceString")
 internal func demangle(
@@ -3727,8 +3727,8 @@ fileprivate func dynamicLibraryAddress<Base, Leaf>(
 ) -> String {
     let getter: ComputedAccessorsPtr.Getter<Base, Leaf> = pointer.getter()
     let pointer = unsafeBitCast(getter, to: UnsafeRawPointer.self)
-    let cString = keypath_dladdr(UnsafeRawPointer(pointer))
-    if let demangled = demangle(name: cString) {
+    if let cString = keypath_dladdr(UnsafeRawPointer(pointer)),
+        let demangled = demangle(name: cString) {
         return String(cString: demangled)
     } else {
         return "<computed \(pointer)>"

stdlib/public/runtime/ReflectionMirror.cpp

@@ -1142,9 +1142,13 @@ const char *swift_keypath_dladdr(void *address) {
 
 SWIFT_CC(swift) SWIFT_RUNTIME_STDLIB_API
 const char *swift_keypathSourceString(char *name) {
-    auto length = strlen(name);
-    auto mangledName = keypathSourceString(name, length);
-    char *rtnValue = new char[mangledName.length() + 1];
-    strcpy(rtnValue, mangledName.c_str());
-    return rtnValue;
+    size_t length = strlen(name);
+    std::string mangledName = keypathSourceString(name, length);
+    if (mangledName == "") {
+        return 0;
+    } else {
+        char *rtnValue = new char[mangledName.length() + 1];
+        strcpy(rtnValue, mangledName.c_str());
+        return rtnValue;
+    }
 }