Split mflags.go into smaller, focused files

[phinze]

mflags.go had grown to ~2300 lines and was getting harder to navigate. It covered four pretty distinct concerns that don't really need to live together: core types and parsing, value type implementations, struct tag reflection, and help rendering.

Broke it into four files along those natural seams. Each file is now in the 150-800 line range, and when you need to add a new value type or tweak help output, you know exactly where to go. No behavior changes, just moving code around within the same package.

Also cleaned up a go vet warning from a test struct that had json/xml tags on an unexported field.

Closes MIR-988

[coderabbitai]

📝 Walkthrough

Walkthrough

This pull request reorganizes the mflags package by refactoring code into separate files. A new fromstruct.go file implements reflection-based flag and positional argument definition from struct fields, including FromStruct and ParseStruct functions with struct tag parsing and validation. A new help.go file provides help output formatting via WriteFlagHelp and ShowHelp methods. A new values.go file contains flag value type implementations for scalars, arrays, pointers, and choice-constrained strings. The main mflags.go file removes these components, and a test file is updated to remove tags from an unexported field.

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[coderabbitai]

🧹 Nitpick comments (1)

help.go (1)

87-146: Consider extracting duplicate max-position calculation logic.

The pattern of finding maxPos by iterating posFields and then iterating 0..maxPos appears twice in ShowHelp() (lines 91-104 and lines 113-124). This is a minor duplication.

♻️ Optional: Extract helper method

// getOrderedPositionalFields returns positional fields sorted by position.
func (f *FlagSet) getOrderedPositionalFields() []*PositionalField {
    if len(f.posFields) == 0 {
        return nil
    }
    maxPos := -1
    for pos := range f.posFields {
        if pos > maxPos {
            maxPos = pos
        }
    }
    result := make([]*PositionalField, 0, maxPos+1)
    for i := 0; i <= maxPos; i++ {
        if field, ok := f.posFields[i]; ok {
            result = append(result, field)
        }
    }
    return result
}

Note: GetPositionalFields() in mflags.go already provides similar functionality and could potentially be reused here.

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@help.go` around lines 87 - 146, ShowHelp currently duplicates the logic that
computes maxPos and iterates 0..maxPos over f.posFields; extract that logic into
a helper and reuse it to avoid duplication. Create or call a helper that returns
ordered positional fields (e.g., getOrderedPositionalFields or reuse existing
GetPositionalFields in mflags.go) and replace the two blocks in ShowHelp that
iterate f.posFields/maxPos with a single loop over the helper's result; keep
handling of f.restField and usage/env formatting unchanged and ensure the helper
returns nil/empty when no positional fields exist.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@help.go`:
- Around line 87-146: ShowHelp currently duplicates the logic that computes
maxPos and iterates 0..maxPos over f.posFields; extract that logic into a helper
and reuse it to avoid duplication. Create or call a helper that returns ordered
positional fields (e.g., getOrderedPositionalFields or reuse existing
GetPositionalFields in mflags.go) and replace the two blocks in ShowHelp that
iterate f.posFields/maxPos with a single loop over the helper's result; keep
handling of f.restField and usage/env formatting unchanged and ensure the helper
returns nil/empty when no positional fields exist.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 8bf0a1e8-ae69-4638-9d88-8ec1a9726eb8

📥 Commits

Reviewing files that changed from the base of the PR and between 1b813c2 and d48e5da.

📒 Files selected for processing (5)

• fromstruct.go
• help.go
• mflags.go
• mflags_test.go
• values.go