Use iterators in FromJson to avoid copies

[Blue (OneBlue)]

Summary of the Pull Request

This change reworks the json parsing logic to work with iterators, which avoids having to copy the entire json into a std::string in some places

PR Checklist

• Closes: Link to issue #xxx
• Communication: I've discussed this with core contributors already. If work hasn't been agreed, this work might be rejected
• Tests: Added/updated if needed and all pass
• Localization: All end user facing strings can be localized
• Dev docs: Added/updated if needed
• Documentation updated: If checked, please file a pull request on our docs repo and link it here: #xxx

Detailed Description of the Pull Request / Additional comments

Validation Steps Performed

[Copilot]

🟡 Changes recommended

The new FromJson template has compile-breaking template-parameter defaults and fragile iterator-to-std::string_view construction that should be corrected before merging.

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Pull request overview

This PR refactors shared JSON deserialization helpers to support parsing directly from iterator ranges, enabling callers to avoid allocating/copying buffers into temporary std::strings before parsing. It also updates WSLc image-import progress parsing to use the new iterator-based API.

Changes:

• Added an iterator-range FromJson overload and routed existing const char* / const wchar_t* overloads through it.
• Updated WSLCSession::ImportImageImpl progress parsing to parse JSON directly from the received buffer iterators.

File summaries

File	Description
src/windows/wslcsession/WSLCSession.cpp	Uses iterator-based FromJson for import-progress parsing to avoid an intermediate std::string copy.
src/shared/inc/JsonUtils.h	Introduces iterator-range JSON parsing and updates overloads/error reporting accordingly.

Review details

Suppressed comments (2)

src/shared/inc/JsonUtils.h:82

• const std::string_view value{First, Last}; depends on the C++23 iterator-range constructor and on Iterator being contiguous; this is likely to break builds or callers that pass non-contiguous iterators. Since this is only used on the exception path, consider materializing a std::string from the iterator range for logging/error text instead.

        const std::string_view value{First, Last};

#ifdef WIN32

        THROW_HR_WITH_USER_ERROR_MSG(

src/shared/inc/JsonUtils.h:101

• FromJson(const char* Value) uses strlen(Value) but this header doesn’t include <cstring> (and on Windows stringshared.h doesn’t include it either), so this can be a fragile/implicit dependency. Prefer std::char_traits<char>::length(Value) (available via <string>) to keep the header self-contained.

T FromJson(const char* Value)
{
    return FromJson<T, TJson>(Value, Value + strlen(Value));
}

• Files reviewed: 2/2 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

Copilot review overview

🔵 Needs a closer look

FromJson(const char*) introduces a new strlen() dependency in a header without ensuring the required include, creating a fragile transitive-include build risk.

Review effort: Lite
Findings: None

Resolved since last review (1)

• FromJson’s template parameter list provides a default for TJson but not for the following…

Previously missed (1)

In code that hasn't changed since last review

Add explicit <cstring> include for strlen dependency

src/​shared/​inc/​JsonUtils.h:97

FromJson(const char* Value) now depends on strlen() but this header doesn’t include <cstring>, so it relies on transitive includes and can break depending on include order/toolset. Prefer a length computation that doesn’t introduce a new header dependency (or explicitly include <cstring>).