Re: [BUG] difference of info from diff and blame

From

Thomas Rast <trast@student.ethz.ch>

Date

Jan 11, 2011, 13:40 UTC

Message-ID

<201101111440.08619.trast@student.ethz.ch>

In-Reply-To

<4D2C333A.3010401@gmail.com>

> 
> I have jquery repo (https://github.com/jquery/jquery.git)
> Let's get blame for some file in some revision:
> git blame -l -s 2ad223aedd1f93c783d98d60adc9fda3bdfbb4b6 -- src/event/event.js
> According to blame, line 127 was added in revision 
> 2ad223aedd1f93c783d98d60adc9fda3bdfbb4b6.

> Let's get diff for that revision:
> git diff-tree -p 2ad223aedd1f93c783d98d60adc9fda3bdfbb4b6 -- src/event/event.js
> We can see this:
> @@ -105,19 +120,16 @@ jQuery.event = {
> 
>   		// Handle triggering a single element
>   		else {
> -			var handler = element["on" + type ], val,
> -				fn = jQuery.isFunction( element[ type
> +			var val, ret, fn = jQuery.isFunction( element
> +			
> +			// Pass along a fake event
> +			data.unshift( this.fix({ type: type, target:
> 

[this blank context line is line 127 in the postimage]

> -			if ( handler ) {
> 
> As you can see line 127 is not marked with '+' char, which means it was 
> not added in this revision. But blame sad otherwise.

And indeed, running

  git show -U0 2ad223ae -- src/event/event.js

in your repository gives a hunk

@@ -108,11 +123,8 @@ jQuery.event = {
-			var handler = element["on" + type ], val,
-				fn = jQuery.isFunction( element[ type ] );
-
-			if ( handler ) {
-				// Pass along a fake event
-				data.unshift( this.fix({ type: type, target: element }) );
-	
-				// Trigger the event
-				if ( (val = handler.apply( element, data )) !== false )
-					this.triggered = true;
-			}
+			var val, ret, fn = jQuery.isFunction( element[ type ] );
+			
+			// Pass along a fake event
+			data.unshift( this.fix({ type: type, target: element }) );
+
+			// Trigger the event
+			if ( (val = this.handle.apply( element, data )) !== false )
+				this.triggered = true;

So I would tend to agree with the blame implementation.  If anything
it's a bug in git-diff when not using any context.

Do you have a reproduction recipe that exhibits the flaw on a
non-whitespace line?  I'm not up to speed on the diff implementation
(maybe someone else can help?), but I wouldn't be too surprised if it
had heuristics that put lines consisting only of whitespace at a lower
importance than "actual" lines.

-- 
Thomas Rast
trast@{inf,student}.ethz.ch