#3333: GHCi doesn't load weak symbols
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Reporter: heatsink | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: GHCi | Version: 6.10.3
Severity: normal | Resolution:
Keywords: weak, dynamic loading | Testcase:
Os: Linux | Architecture: x86
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Comment (by heatsink):
I investigated the linking rules for weak symbols in ELF,
http://www.skyfree.org/linux/references/ELF_Format.pdf . If I understand
correctly, the linking precedence is:
global undefined < weak undefined < weak defined < global defined
The highest-precedence symbol is used for relocation. If it's "weak
undefined", then the symbol gets an absolute address of NULL. If "weak
defined", an arbitrary definition of the symbol is chosen. This should be
do-able when loading a batch of object files.
Because libraries get loaded incrementally, not all situations can be
handled properly. If a previously loaded weak symbol would get "promoted"
to a higher precedence, GHCi will have to abort, as it currently does for
conflicting global definitions.
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/3333#comment:1>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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