Assigning to self twice in init provokes spurious warning about not assigning at all

[llvmbot]

Bugzilla Link	9094
Resolution	FIXED
Resolved on	Feb 04, 2011 23:57
Version	trunk
OS	MacOS X
Attachments	example
Reporter	LLVM Bugzilla Contributor
CC	@akyrtzi,@tkremenek

Extended Description

A common pattern in classes with multiple initializers (for example NSView with -initWithFrame: and -initWithCoder:) is to put the subclass's common initialization bits into a static function. If you structure this so that the common init can fail and return nil, then you can end up with something like this:

• init;
  {
  if (!(self = [super init]))
  return nil;
  if (!(self = _commonInit(self)))
  return nil;

  return self;
  }

This provokes a warning about never having assigned self before returning it, which is not true:

double-assign-self.m:28:5: warning: Returning 'self' before setting it to the result of '[(super or self) init...]'

[llvmbot]

assigned to @tkremenek

[tkremenek]

cloned to rdar://problem/8937441

[akyrtzi]

Two issues I see:

1. The message should change to "Returning 'self' while it is not set to the
   result of '[(super or self) init...]'" to make it more clear why the warning is emitted.
2. Should whitelist function calls as valid initialization for self.

I'll investigate 2) to see its effect (whether it will hide actual bugs).

Any thoughts about the above ?

[tkremenek]

I'll investigate 2) to see its effect (whether it will hide actual bugs).

I think (2) should only apply after the super class bits have been initialized.

[akyrtzi]

Fixed at r124940. Thanks for the report!