flag: prevent BoolWithInverseFlag.String from panicking without a tab#2311
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alliasgher wants to merge 1 commit intourfave:mainfrom
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flag: prevent BoolWithInverseFlag.String from panicking without a tab#2311alliasgher wants to merge 1 commit intourfave:mainfrom
alliasgher wants to merge 1 commit intourfave:mainfrom
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When FlagStringer returns a string without a tab character, strings.Index returns -1 and out[-1:] panics with "slice bounds out of range [-1:]". Guard against this by clamping the index to 0 when no tab is found. In that case the entire FlagStringer output is used as the suffix portion of the formatted string, matching the intent of callers who use a custom stringer without the usual tab layout. Fixes urfave#2303 Signed-off-by: alliasgher <alliasgher123@gmail.com>
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Summary
BoolWithInverseFlag.String()panics withslice bounds out of range [-1:]whenFlagStringerreturns a string without a tab character.The code uses
strings.Index(out, "\t")and then slicesout[i:]. When no tab is present,iis-1andout[-1:]panics.Before
Fix
Clamp
ito0whenstrings.Indexreturns-1. In that case the entire stringer output is used as the suffix, which is the safest non-panicking behaviour.Fixes #2303
Checklist
TestBoolWithInverseFlagStringNoPanicWithNoTabStringer)