fix(encoding): render <nil> for typed-nil Stringer pointers instead of panicking#27
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fix(encoding): render <nil> for typed-nil Stringer pointers instead of panicking#27SAY-5 wants to merge 1 commit into
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…f panicking When an attribute value is a typed-nil pointer whose element type has a String method (the canonical case being (*time.Time)(nil), because time.Time.String auto-generates a pointer receiver wrapper), the interface assertion 'case fmt.Stringer' still matched, and calling v.String() dispatched the method on a nil receiver. The runtime then panicked with 'value method time.Time.String called using nil *Time pointer' and took down the handler - surfacing in real apps as a crash whenever an optional *time.Time field was unset (phsym#22). Guard the Stringer branch with reflect: if the interface value holds a nil pointer, write the literal <nil> and return, matching the default Go format for a nil Stringer. For any non-nil Stringer, or a Stringer that does not resolve to a pointer (struct-by-value implementations, custom types), behaviour is unchanged. Add a regression test that passes a nil *time.Time as an attribute to the handler and asserts the output is 'INF foobar expiration=<nil>' rather than a panic. The test fails on master with the exact panic signature from the report. Closes phsym#22 Signed-off-by: SAY-5 <SAY-5@users.noreply.github.com>
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What
Fixes #22.
When an attribute value is a typed-nil pointer whose element type has a
Stringmethod - the canonical case being(*time.Time)(nil), becausetime.Time.Stringauto-generates a pointer-receiver wrapper - the interface assertioncase fmt.Stringerstill matched. Callingv.String()then dispatched the method on a nil receiver and the runtime panicked with:which took down the handler. In real apps this surfaced as a crash every time an optional
*time.Timefield was logged without being populated.Fix
Guard the Stringer branch with reflect: if the interface value holds a nil pointer, write the literal
<nil>and return - matching the default Go format for a nil Stringer. For any non-nil Stringer, or a Stringer that does not resolve to a pointer (struct-by-value implementations, custom types), behaviour is unchanged.Tests
Added
TestHandler_NilStringerPointerthat passes a nil*time.Timeas an attribute to the handler and asserts the output is exactlyINF foobar expiration=<nil>\nrather than a panic. The test fails on master with the exact panic signature from the report; with the fix it passes.Verification
Locally on macOS, go 1.26.2:
gofmt -s -l: cleango vet ./...: cleango test -race -count=1 ./...: full suite passCloses #22