The TracePoint bumb!

'SJ The TracePoint Bomb! ,PJDIJ*50&4. *OD 3VCZ,BJHJ 'VLVPLB*OUFSOBUJPOBM$POHSFTT$FOUFS Bug
of the year 2018

!LPJD w 3VCP$PQ$PNNJUUFS w "30SBDMFFOIBODFE BEBQUFS$PNNJUUFS w $PNNVOJUZ.BOBHFS BU&4. *OD

&4. *OD

044ίϛϡχςΟͱͷڞੜΛࢧԉ Support coexistence with OSS community

!ZBIPOEBTBJEBU3BJMTEN “I appreciate valuable relationships with people who create, break,
and fix software”

This story  I broke a gem

“TracePoint bomb” "3VCZDPNNJUUFSTBZT IUUQTUXJUUFSDPNNSLOTUBUVT

5IFCFHJOOJOHPG  UIFCPNC

8FC.PDL$*GBJMVSF IUUQTUSBWJTDJPSHCCMJNLFXFCNPDLKPCT--

TVQFS /FU#V⒎FSFE*0 8FC.PDLFYUFOET3VCZ`TTUEMJC SCVG@pMM 8FC.PDL/FU#V⒎FSFE*0 SCVG@pMM

TVQFS /FU#V⒎FSFE*0 /FUTUEMJC"1*DIBOHFE SCVG@pMM 8FC.PDL/FU#V⒎FSFE*0 SCVG@pMM

SVCZSVCZ!CGDG OFUQSPUPDPMSFBEEJSFDUMZJOUPSCVGJGJUTFNQUZ

Net::BufferedIO#rbuf_fill

Net::BufferedIO#rbuf_fill The value for the second default arg is `nil`

Net::BufferedIO#rbuf_fill Changed to assign the value of `@rbuf` or `nil`
The value for the second default arg is `nil`

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`

CCMJNLFXFCNPDL 1SFWFOUA/FU3FBE5JNFPVUAFSSPSJO3VCZ

TVQFS /FU#V⒎FSFE*0 'PMMPXTVQFSDMBTTDIBOHFT SCVG@pMM 8FC.PDL/FU#V⒎FSFE*0 SCVG@pMM

WebMockNetBufferedIO#rbuf_fill

8IBUJT5SBDF1PJOU class Framework end

"TTJHOUPMWBS class Framework def initialize hard_config = '' end end

%FpOFBNFUIPEUPTIPXUIFMWBS class Framework def initialize hard_config = '' @config_for_debug =
"#{self.class}: #{hard_config}" end def config @config_for_debug end end

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 #=> ''

%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

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)`

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

"#{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

"#{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

WebMockNetBufferedIO#rbuf_fill (Repeat)

w*EJEOPUXBOUUPXSJUFB NFUIPEPWFSXSJUUFODPEFT VTJOHDPQZBOEQBTUF w*EJEOPUXBOUUPEVQBMPU PGDPEFTUPJNQMFNFOU TNBMMEJGGFSFODF 8IZ5SBDF1PJOU

w(PUIFPQQPTJUFPG3VCZ Y w8FC.PDLJTBMJCSBSZGPS UFTUJOH w*UTIPVMEOPUBGGFDU QSPEVDUJPOSVOUJNF 5SBDF1PJOUJTTMPX

.ZQBUDIXBTSFMFBTFE

9 months later

“Ruby is funny because this method returns nil” "3VCZDPNNJUUFSTBZT IUUQTUXJUUFSDPN@LPTUBUVT

CCMJNLFXFCNPDL EJTBCMF5SBDF1PJOUQSPQFSMZ

*GPSHPUAFOTVSFA

A5SBDF1PJOUAXBTFOBCMFEHMPCBMMZ XIFOBOFYDFQUJPOPDDVST *GPSHPUAFOTVSFA

Fall through A5SBDF1PJOUAXBTFOBCMFEHMPCBMMZ XIFOBOFYDFQUJPOPDDVST *GPSHPUAFOTVSFA

“Ruby is funny because this method returns nil” "3VCZDPNNJUUFSTBZT IUUQTUXJUUFSDPN@LPTUBUVT

w#FDBSFGVMJGZPVVTF5SBDF1PJOU UPIBSEEFQFOEPOJOUFSOBM JNQMFNFOUBUJPO w#FDBSFGVMXIFOVTJOH5SBDF1PJOU XJUIA#JOEJOHMPDBM@WBSJBCMF@TFUA w-FUTDSFBUFFYUFOTJPOQPJOUTUP UIFVQTUSFBNGPSFBTZFYUFOTJPO %PTBHFBOE"ENJOJTUSBUJPO

“The culprit was koic" "3VCZDPNNJUUFSTBZT IUUQTUXJUUFSDPN@LPTUBUVT

“Thanks for using Ruby's trunk” "3VCZDPNNJUUFSTBZT IUUQTUXJUUFSDPNLLVCVOTUBUVT

Koichi fixes Koichi’s bug ,PJDIJ*50&4. *OD Bug of the year
2018 5IBOLZPVGPSMJTUFOJOH

Culprit Koichi Ito Detective Koichi Sasada Cast

l 5IFSFBSFOPCVHTJOGSPOUPGNF #VHTBSFCFIJOENF !OPCV

.FTTBHFTGSPN3VCZDPNNJUUFST 1SFTFOUFECZBNBUTVEBBOE3VCZ%FWFMPQNFOUUFBN

5IFQBUDINPOTUFSTBZT “Bug of the year”

The TracePoint bumb!

The TracePoint bumb!

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