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'SJ
The TracePoint
Bomb!
,PJDIJ*50&4.
*OD
3VCZ,BJHJ
'VLVPLB*OUFSOBUJPOBM$POHSFTT$FOUFS
Bug of the year 2018
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!LPJD
w 3VCP$PQ$PNNJUUFS
w "30SBDMFFOIBODFE
BEBQUFS$PNNJUUFS
w $PNNVOJUZ.BOBHFS
BU&4.
*OD
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&4.
*OD
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044ίϛϡχςΟͱͷڞੜΛࢧԉ
Support coexistence with OSS community
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!ZBIPOEBTBJEBU3BJMTEN
“I appreciate valuable
relationships with people who
create, break, and fix software”
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No content
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This story
I broke a gem
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“TracePoint bomb”
"3VCZDPNNJUUFSTBZT
IUUQTUXJUUFSDPNNSLOTUBUVT
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5IFCFHJOOJOHPG
UIFCPNC
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.BS
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8FC.PDL$*GBJMVSF
IUUQTUSBWJTDJPSHCCMJNLFXFCNPDLKPCT--
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TVQFS
/FU#V⒎FSFE*0
8FC.PDLFYUFOET3VCZ`TTUEMJC
SCVG@pMM
8FC.PDL/FU#V⒎FSFE*0
SCVG@pMM
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TVQFS
/FU#V⒎FSFE*0
/FUTUEMJC"1*DIBOHFE
SCVG@pMM
8FC.PDL/FU#V⒎FSFE*0
SCVG@pMM
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SVCZSVCZ!CGDG
OFUQSPUPDPMSFBEEJSFDUMZJOUPSCVGJGJUTFNQUZ
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Net::BufferedIO#rbuf_fill
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Net::BufferedIO#rbuf_fill
The value for the second
default arg is `nil`
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Net::BufferedIO#rbuf_fill
Changed to assign the value
of `@rbuf` or `nil`
The value for the second
default arg is `nil`
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Net::BufferedIO#rbuf_fill
Use the lvar `tmp`
Changed to assign the value
of `@rbuf` or `nil`
The value for the second
default arg is `nil`
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CCMJNLFXFCNPDL
1SFWFOUA/FU3FBE5JNFPVUAFSSPSJO3VCZ
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No content
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TVQFS
/FU#V⒎FSFE*0
'PMMPXTVQFSDMBTTDIBOHFT
SCVG@pMM
8FC.PDL/FU#V⒎FSFE*0
SCVG@pMM
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WebMockNetBufferedIO#rbuf_fill
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8IBUJT5SBDF1PJOU
class Framework
end
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"TTJHOUPMWBS
class Framework
def initialize
hard_config = ''
end
end
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%FpOFBNFUIPEUPTIPXUIFMWBS
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
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MWBSTIPXFEJT
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
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%FpOFBTVCDMBTT
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
class Application < Framework
end
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6TFAMPDBM@WBSJBCMF@TFUA
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
class Application < Framework
def initialize
trace = TracePoint.trace(:line) do |tp|
tp.binding.local_variable_set(:hard_config, '')
end
super
trace.disable
end
end
Specify the event to
evaluate the expression
with `trace(:line)`
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6TFAMPDBM@WBSJBCMF@TFUA
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
class Application < Framework
def initialize
trace = TracePoint.trace(:line) do |tp|
tp.binding.local_variable_set(:hard_config, '')
end
super
trace.disable
end
end
4QFDJGZMWBSAIBSE@DPOpHA
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MWBSTIPXFEJT
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
class Application < Framework
def initialize
trace = TracePoint.trace(:line) do |tp|
tp.binding.local_variable_set(:hard_config, '')
end
super
trace.disable
end
end
p Application.new.config #=> ''
4QFDJGZMWBSAIBSE@DPOpHA
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MWBSTIPXFEJT
class Framework
def initialize
hard_config = ''
@config_for_debug = "#{self.class}: #{hard_config}"
end
def config
@config_for_debug
end
end
p Framework.new.config #=> ''
class Application < Framework
def initialize
trace = TracePoint.trace(:line) do |tp|
tp.binding.local_variable_set(:hard_config, '')
end
super
trace.disable
end
end
p Application.new.config #=> ''
p Framework.new.config #=> ''
4QFDJGZMWBSAIBSE@DPOpHA
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WebMockNetBufferedIO#rbuf_fill
(Repeat)
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w*EJEOPUXBOUUPXSJUFB
NFUIPEPWFSXSJUUFODPEFT
VTJOHDPQZBOEQBTUF
w*EJEOPUXBOUUPEVQBMPU
PGDPEFTUPJNQMFNFOU
TNBMMEJGGFSFODF
8IZ5SBDF1PJOU
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w(PUIFPQQPTJUFPG3VCZ
Y
w8FC.PDLJTBMJCSBSZGPS
UFTUJOH
w*UTIPVMEOPUBGGFDU
QSPEVDUJPOSVOUJNF
5SBDF1PJOUJTTMPX
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.ZQBUDIXBTSFMFBTFE
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9 months later
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%FD
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No content
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“Ruby is funny because this method returns nil”
"3VCZDPNNJUUFSTBZT
IUUQTUXJUUFSDPN@LPTUBUVT
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CCMJNLFXFCNPDL
EJTBCMF5SBDF1PJOUQSPQFSMZ
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No content
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No content
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*GPSHPUAFOTVSFA
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A5SBDF1PJOUAXBTFOBCMFEHMPCBMMZ
XIFOBOFYDFQUJPOPDDVST
*GPSHPUAFOTVSFA
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Fall through
A5SBDF1PJOUAXBTFOBCMFEHMPCBMMZ
XIFOBOFYDFQUJPOPDDVST
*GPSHPUAFOTVSFA
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“Ruby is funny because this method returns nil”
"3VCZDPNNJUUFSTBZT
IUUQTUXJUUFSDPN@LPTUBUVT
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w#FDBSFGVMJGZPVVTF5SBDF1PJOU
UPIBSEEFQFOEPOJOUFSOBM
JNQMFNFOUBUJPO
w#FDBSFGVMXIFOVTJOH5SBDF1PJOU
XJUIA#JOEJOHMPDBM@WBSJBCMF@TFUA
w-FUTDSFBUFFYUFOTJPOQPJOUTUP
UIFVQTUSFBNGPSFBTZFYUFOTJPO
%PTBHFBOE"ENJOJTUSBUJPO
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“The culprit was koic"
"3VCZDPNNJUUFSTBZT
IUUQTUXJUUFSDPN@LPTUBUVT
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“Thanks for using Ruby's trunk”
"3VCZDPNNJUUFSTBZT
IUUQTUXJUUFSDPNLLVCVOTUBUVT
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Koichi fixes
Koichi’s bug
,PJDIJ*50&4.
*OD
Bug of the year 2018
5IBOLZPVGPSMJTUFOJOH
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Culprit
Koichi Ito
Detective
Koichi Sasada
Cast
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l
5IFSFBSFOPCVHTJOGSPOUPGNF
#VHTBSFCFIJOENF
!OPCV
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.FTTBHFTGSPN3VCZDPNNJUUFST
1SFTFOUFECZBNBUTVEBBOE3VCZ%FWFMPQNFOUUFBN
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5IFQBUDINPOTUFSTBZT
“Bug of the year”