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In the event that the input is just JSON whitespace,
the underlying jsontext.Decoder treats this as an empty stream
and reports io.EOF.
The logic in unmarshalFull simply casted io.EOF as io.ErrUnexpectedEOF,
which is inconsistent with how all other io.ErrUnexpectedEOF are reported,
which are wrapped within a jsontext.SyntacticError.
Do the same thing for consistency.
We add a v1 test (without goexperiment.jsonv2) to verify that
the behavior is identical to how v1 has always behaved.
We add a v1in2 test (with goexperiment.jsonv2) to verify that
the v1in2 behavior correctly replicates historical v1 behavior.
We also fix a faulty check in v1 Decoder.Decode,
where it tried to detect errUnexpectedEnd and
return an unwrapped io.ErrUnexpectedEOF error.
This is the exact semantic that v1 has always done
in streaming Decoder.Decode (but not non-streaming Unmarshal).
There is a prior bug reported in #25956 about this inconsistency,
but we aim to preserve historical v1 behavior to reduce
the probability of churn when v1 is re-implemented in terms of v2.
Fixes #74548
Change-Id: Ibca52c3699ff3c09141e081c85f853781a86ec8e
Reviewed-on: https://go-review.googlesource.com/c/go/+/687115
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Carlos Amedee <carlos@golang.org>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Damien Neil <dneil@google.com>
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Based on the discussion in #71631, it is hotly contested
whether the default JSON representation for a Go time.Duration
should be the time.Duration.String format or
a particular profile of ISO 8601.
Regardless of the default, it seems clear that we should
at least support ISO 8601 if specified via a format flag.
Note that this CL does not alter the default representation.
Unfortunately, ISO 8601 is a large and evolving standard
with many optional extensions and optional restrictions.
Thus, the term "ISO 8601 duration" unfortunately does not
resolve to a particular grammar, nor one that is stable.
However, there is precedence that we can follow in this matter.
JSON finds its heritage in JavaScript and
JavaScript is adding a Temporal.Duration type whose default
JSON representation is ISO 8601.
There is a well-specified grammar for their particular
profile of ISO 8601, which is documented at:
https://tc39.es/proposal-temporal/#prod-Duration
This particular CL adds support for ISO 8601 according to
the exact same grammar that JavaScript uses.
While Temporal.Duration is technically still a proposal,
it is already in stage 3 of the TC39 proposal process
(i.e., "no changes to the proposal are expected"
and "has been recommended for implementation")
and therefore close to final adoption.
One major concern with ISO 8601 is that it supports
nominal date units like years, months, weeks, and days
that do not have an accurate meaning without being
anchored to a particular point in time and place on Earth.
Fortunately, JavaScript (by default) avoids producing
Temporal.Duration values with nominal units unless
arithmetic in JavaScript explicitly sets a largestUnits
value that is larger than "hours". In the Go implementation,
we support syntactically parsing the full ISO 8601 grammar
(according to JavaScript), but semantically report an error if
nominal units are present. This ensures that ISO 8601 durations
remain accurate so long as they only use the accurate units
of hours, minutes, or seconds.
Updates #71631
Change-Id: I983593662f2150461ebc486a5acfeb72f0286939
Reviewed-on: https://go-review.googlesource.com/c/go/+/682403
Reviewed-by: Daniel Martà <mvdan@mvdan.cc>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Joseph Tsai <joetsai@digital-static.net>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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