Bug 115047

Summary: RetainPtr.h should compile with -Wshorten-64-to-32
Product: WebKit Reporter: David Kilzer (:ddkilzer) <ddkilzer>
Component: Web Template FrameworkAssignee: David Kilzer (:ddkilzer) <ddkilzer>
Status: RESOLVED FIXED    
Severity: Normal CC: andersca, benjamin, cmarcelo, commit-queue, darin, kling, mitz, mjs, sam
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Bug Depends on:    
Bug Blocks: 107093    
Attachments:
Description Flags
Patch v1
none
Patch v2 none

David Kilzer (:ddkilzer)
Reported 2013-04-23 10:52:22 PDT
RetainPtr.h:318:20: error: implicit conversion loses integer precision: 'CFHashCode' (aka 'unsigned long') to 'unsigned int' [-Werror,-Wshorten-64-to-32] return CFHash(o.get()); ~~~~~~ ^~~~~~~~~~~~~~~ CFHash() returns a CFHashCode, which is typedef-ed to 'unsigned long', which is 4 bytes on 32-bit architectures (which matches 'unsigned'), but 8 bytes on 64-bit architectures. I see two possible fixes here: 1. Use a static_cast<uint32_t>() operator to just take the lower 4 bytes for the hash code. This is what is implicitly happening now. 2. Use static_cast<uint64_t>() with WTF::intHash() to generate a new 4-byte hash code using the 8-byte CFHashCode. Thoughts?
Attachments
Patch v1 (1.74 KB, patch)
2013-04-23 11:34 PDT, David Kilzer (:ddkilzer) 		no flags
DetailsFormatted DiffDiff
Patch v2 (1.74 KB, patch)
2013-04-23 11:42 PDT, David Kilzer (:ddkilzer) 		no flags
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
David Kilzer (:ddkilzer)
Comment 1 2013-04-23 11:34:15 PDT
Created attachment 199310 [details] Patch v1
Anders Carlsson
Comment 2 2013-04-23 11:39:28 PDT
Comment on attachment 199310 [details] Patch v1 View in context: https://bugs.webkit.org/attachment.cgi?id=199310&action=review > Source/WTF/wtf/RetainPtr.h:318 > + return static_cast<uint32_t>(CFHash(o.get())); Wouldn’t it be better to cast to the function's return type (unsigned)?
David Kilzer (:ddkilzer)
Comment 3 2013-04-23 11:40:54 PDT
(In reply to comment #2) > (From update of attachment 199310 [details]) > View in context: https://bugs.webkit.org/attachment.cgi?id=199310&action=review > > > Source/WTF/wtf/RetainPtr.h:318 > > + return static_cast<uint32_t>(CFHash(o.get())); > > Wouldn’t it be better to cast to the function's return type (unsigned)? Yes.
David Kilzer (:ddkilzer)
Comment 4 2013-04-23 11:42:34 PDT
Created attachment 199311 [details] Patch v2
WebKit Commit Bot
Comment 5 2013-04-23 12:14:29 PDT
Comment on attachment 199311 [details] Patch v2 Clearing flags on attachment: 199311 Committed r148979: <http://trac.webkit.org/changeset/148979>
WebKit Commit Bot
Comment 6 2013-04-23 12:14:32 PDT
All reviewed patches have been landed. Closing bug.
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