pass full string_view to enum_from_string in value_to

[Ramya-9353]

Repro: value_to<E>() for a described enum, given a JSON string whose bytes are an enumerator name followed by an embedded U+0000 (e.g. "admin\u0000x"), returns that enumerator instead of failing. parse_into<E>() rejects the same document with unknown_name.

Cause: the described-enum handler calls describe::enum_from_string(str->data(), val). str->data() is a char const*, which selects the overload that matches with std::strcmp, so the name is truncated at the first null. The streaming parse_into enum handler already passes a string_view, whose comparison spans the whole run, so the two APIs disagree on the same input.

Fix: pass str->subview() so the string_view overload is selected and the full string, including any embedded null, is compared.

Regression test added to test/value_to.cpp: value_to<E1> of a two-byte string "a\0" throws before the change and is rejected after; the existing enum cases still pass.

[cppalliance-bot]

An automated preview of the documentation is available at https://1201.json.prtest2.cppalliance.org/libs/json/doc/html/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-09-26 20:39:00 UTC

[cppalliance-bot]

GCOVR code coverage report https://1201.json.prtest2.cppalliance.org/gcovr/index.html
LCOV code coverage report https://1201.json.prtest2.cppalliance.org/genhtml/index.html
Coverage Diff Report https://1201.json.prtest2.cppalliance.org/diff-report/index.html

Build time: 2026-09-26 21:08:08 UTC

[cppalliance-bot]

Benchmark test results. More info at https://benchmark.cppalliance.org/jsonbenchmarks-pullrequests/1201/pullrequest.html

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.98%. Comparing base (fc70d23) to head (0789993).

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1201   +/-   ##
========================================
  Coverage    93.98%   93.98%           
========================================
  Files           85       85           
  Lines         8973     8973           
========================================
  Hits          8433     8433           
  Misses         540      540           

Files with missing lines	Coverage Δ
include/boost/json/detail/value_to.hpp	99.11% <100.00%> (ø)

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