Bug 137323 - Fail better when is<>() / downcast<>() is used for an unsupported type
Summary: Fail better when is<>() / downcast<>() is used for an unsupported type
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: DOM (show other bugs)
Version: 528+ (Nightly build)
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Chris Dumez
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2014-10-01 16:35 PDT by Chris Dumez
Modified: 2014-10-01 19:22 PDT (History)
6 users (show)

See Also:


Attachments
Patch (2.24 KB, patch)
2014-10-01 16:52 PDT, Chris Dumez
no flags Details | Formatted Diff | Diff

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Description Chris Dumez 2014-10-01 16:35:05 PDT
We should fail better when is<>() / downcast<>() is used for an unsupported type (i.e. a type that doesn't have the needed TypeCastTraits template specialization).

Currently, we get an obscure linking error, which is sub-optimal.
Comment 1 Chris Dumez 2014-10-01 16:52:17 PDT
Created attachment 239067 [details]
Patch
Comment 2 Chris Dumez 2014-10-01 16:56:09 PDT
Comment on attachment 239067 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=239067&action=review

> Source/WTF/wtf/TypeCasts.h:42
> +        static_assert(std::is_void<ExpectedType>::value, "Missing TypeCastTraits specialization");

I cannot use a static_assert(false, ""); because the compiler would then evaluate it and fail the build even if this template was not instantiated. By having the static_assert() depend on the template parameter type, I avoid that issue and we hit the static_assert() only if this is actually instantiated. And this one is only instantiated if there is no specialization for the type.
Comment 3 WebKit Commit Bot 2014-10-01 18:18:51 PDT
Comment on attachment 239067 [details]
Patch

Clearing flags on attachment: 239067

Committed r174193: <http://trac.webkit.org/changeset/174193>
Comment 4 WebKit Commit Bot 2014-10-01 18:18:57 PDT
All reviewed patches have been landed.  Closing bug.
Comment 5 Gyuyoung Kim 2014-10-01 19:02:06 PDT
EFL port has been broken since r174193.

https://build.webkit.org/builders/EFL%20Linux%2064-bit%20Release%20WK2/builds/16694
Comment 6 Chris Dumez 2014-10-01 19:22:04 PDT
(In reply to comment #5)
> EFL port has been broken since r174193.
> 
> https://build.webkit.org/builders/EFL%20Linux%2064-bit%20Release%20WK2/builds/16694

Build fix landed in <http://trac.webkit.org/changeset/174195>