Bug 154162 – GCC buildfix in Source/WebCore/svg/SVGToOTFFontConversion.cpp

• Component: New Bugs
• Status: RESOLVED FIXED

[Csaba Osztrogonác]

build error:
../../Source/WebCore/svg/SVGToOTFFontConversion.cpp: In member function 'size_t WebCore::SVGToOTFFontConverter::finishAppendingKERNSubtable(WTF::Vector<WebCore::SVGToOTFFontConverter::KerningData>, uint16_t)':
../../Source/WebCore/svg/SVGToOTFFontConversion.cpp:1100:30: error: use of 'kerningData' before deduction of 'auto'

Source/WebCore/svg/SVGToOTFFontConversion.cpp:
...
for (auto& kerningData : kerningData) {
     append16(kerningData.glyph1);
     append16(kerningData.glyph2);
     append16(kerningData.adjustment);
}
...

GCC can't handle properly if we use the same variable name in 
range declaration as in range expression of range-based for loop.
(tested with GCC 4.9 and 5.2 too.) 

The simplest workaround is renaming one of the variable.
Explicit type declaration isn't enough for GCC.

We needed the same workaround previously - bug151622 .

[Csaba Osztrogonác]

Created attachment 271164 [details]
Patch

[Csaba Osztrogonác]

I don't like at all to use the same variable name for the 
element and for the collection in range-based for loop,
but I think it is a GCC bug, so I reported it:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69784

[Andreas Kling]

Comment on attachment 271164 [details]
Patch

huh!

[Csaba Osztrogonác]

Comment on attachment 271164 [details]
Patch

Clearing flags on attachment: 271164

Committed r196469: <http://trac.webkit.org/changeset/196469>

[Csaba Osztrogonác]

All reviewed patches have been landed.  Closing bug.

[Darin Adler]

Comment on attachment 271164 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=271164&action=review

> Source/WebCore/svg/SVGToOTFFontConversion.cpp:1104
> +    for (auto& kerningDataElement : kerningData) {
> +        append16(kerningDataElement.glyph1);
> +        append16(kerningDataElement.glyph2);
> +        append16(kerningDataElement.adjustment);
>      }

I’m happy with this fix.

However, I wanted to point out for future reference in WebKit coding style that when a variable has really small scope like this, it’s often good practice to give it a shorter name since the context makes its meaning clear without the name having to express everything. Hence, I would have named this local variable "element" or "pair" rather than using a multi-word phrase.