Null ptr error in -[NSAppleScript executeAndReturnError:]

[lhz07]

found an issue in the generated binding for -[NSAppleScript executeAndReturnError:].

The current Rust signature is:

/// # Safety
///
/// `error_info` generic should be of the correct type.
#[unsafe(method(executeAndReturnError:))]
#[unsafe(method_family = none)]
pub unsafe fn executeAndReturnError(
    &self,
    error_info: Option<&mut Option<Retained<NSDictionary<NSString, AnyObject>>>>,
) -> Retained<NSAppleEventDescriptor>;

However, according to Apple’s documentation, the Objective-C method is:

- (NSAppleEventDescriptor *)executeAndReturnError:(NSDictionary<NSString *, id> **)errorInfo;
// Return Value: The result of executing the event, or nil if an error occurs.

The return value is nullable. But the generated Rust binding uses Retained<NSAppleEventDescriptor> instead of an Option<Retained<…>>. As a result, when the AppleScript execution fails, the Rust code panics:

thread '<unnamed>' panicked at .cargo/registry/src/index.crates.io-1949cf8c6b5b557f/objc2-foundation-0.3.2/src/generated/NSAppleScript.rs:60:5:
unexpected NULL returned from -[NSAppleScript executeAndReturnError:]

[lhz07]

It appears this might actually originate from the Apple SDK headers.
NSAppleScript.h is wrapped in NS_HEADER_AUDIT_BEGIN(nullability, sendability), but the return value of -executeAndReturnError: is not annotated as nullable, even though the documentation clearly states it may return nil on failure.

Because the SDK omits the nullability annotation, the generated binding ends up treating the return value as non-null, which leads to a panic when the Objective-C API returns nil.

/*
	NSAppleScript.h
	Copyright (c) 2002-2019, Apple Inc. All rights reserved.
*/

#import <Foundation/NSObject.h>


@class NSAppleEventDescriptor, NSDictionary<KeyType, ObjectType>, NSString, NSURL;

NS_HEADER_AUDIT_BEGIN(nullability, sendability)

// If the result of -initWithContentsOfURL:error:, -compileAndReturnError:, -executeAndReturnError:, or -executeAppleEvent:error:, signals failure (nil, NO, nil, or nil, respectively), a pointer to an autoreleased dictionary is put at the location pointed to by the error parameter.  The error info dictionary may contain entries that use any combination of the following keys, including no entries at all.
FOUNDATION_EXPORT NSString *const NSAppleScriptErrorMessage API_AVAILABLE(macos(10.2)) API_UNAVAILABLE(ios, watchos, tvos); // NSString
FOUNDATION_EXPORT NSString *const NSAppleScriptErrorNumber API_AVAILABLE(macos(10.2)) API_UNAVAILABLE(ios, watchos, tvos); // NSNumber
FOUNDATION_EXPORT NSString *const NSAppleScriptErrorAppName API_AVAILABLE(macos(10.2)) API_UNAVAILABLE(ios, watchos, tvos); // NSString
FOUNDATION_EXPORT NSString *const NSAppleScriptErrorBriefMessage API_AVAILABLE(macos(10.2)) API_UNAVAILABLE(ios, watchos, tvos); // NSString
FOUNDATION_EXPORT NSString *const NSAppleScriptErrorRange API_AVAILABLE(macos(10.2)) API_UNAVAILABLE(ios, watchos, tvos); // NSValue containing an NSRange

@interface NSAppleScript : NSObject<NSCopying> {
    @private
    NSString *_source;
    unsigned int _compiledScriptID;
    void *_reserved1;
    void *_reserved2;
}

// Given a URL that locates a script, in either text or compiled form, initialize.  Return nil and a pointer to an error information dictionary if an error occurs.  This is a designated initializer for this class.
- (nullable instancetype)initWithContentsOfURL:(NSURL *)url error:(NSDictionary<NSString *, id> * _Nullable * _Nullable)errorInfo NS_DESIGNATED_INITIALIZER;

// Given a string containing the AppleScript source code of a script, initialize.  Return nil if an error occurs.  This is also a designated initializer for this class.
- (nullable instancetype)initWithSource:(NSString *)source NS_DESIGNATED_INITIALIZER;

// Return the source code of the script if it is available, nil otherwise.  It is possible for an NSAppleScript that has been instantiated with -initWithContentsOfURL:error: to be a script for which the source code is not available, but is nonetheless executable.
@property (nullable, readonly, copy) NSString *source;

// Return yes if the script is already compiled, no otherwise.
@property (readonly, getter=isCompiled) BOOL compiled;

// Compile the script, if it is not already compiled.  Return yes for success or if the script was already compiled, no and a pointer to an error information dictionary otherwise.
- (BOOL)compileAndReturnError:(NSDictionary<NSString *, id> * _Nullable * _Nullable)errorInfo;

// Execute the script, compiling it first if it is not already compiled.  Return the result of executing the script, or nil and a pointer to an error information dictionary for failure.
- (NSAppleEventDescriptor *)executeAndReturnError:(NSDictionary<NSString *, id> * _Nullable * _Nullable)errorInfo;

// Execute an Apple event in the context of the script, compiling the script first if it is not already compiled.  Return the result of executing the event, or nil and a pointer to an error information dictionary for failure.
- (NSAppleEventDescriptor *)executeAppleEvent:(NSAppleEventDescriptor *)event error:(NSDictionary<NSString *, id> * _Nullable * _Nullable)errorInfo;

@end

NS_HEADER_AUDIT_END(nullability, sendability)

[madsmtm]

Swift has the same issue (the method returns NSAppleEventDescriptor instead of NSAppleEventDescriptor?).

Would you mind submitting a bug report upstream to Apple via their Feedback Assistant?

We can fix this locally, but it'll be a breaking change, so it'll probably have to wait until v0.4.

[lhz07]

Great, I have submitted a bug report