Go Struct Tags Manager

VSCode extension for Go struct field tags: syntax highlighting, sorting, and alignment.

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Features

Syntax Highlighting

Tags are colored using your current theme - no hardcoded colors, no background overrides that would break selection highlighting.

Each part of a tag gets a distinct color from the active theme:

• Key (json, yaml, db, …) - attribute color
• Value ("my_field") - string color
• Option (omitempty, required, min=1) - constant color
• Separator (,) - punctuation color

CodeLens Actions

Three inline actions appear above every struct that has tagged fields:

Sort & Align Tags  |  Sort Tags  |  Align Tags
type UserProfile struct {

Sort Tags

Reorders tag keys across all fields of a struct to a consistent canonical order.

first-field mode (default) - order is derived from the first field: keys present there come first, the rest follow in the order they are first encountered across the struct.

Before:

type User struct {
    ID    int    `json:"id"    yaml:"id"`
    Name  string `yaml:"name" json:"name" db:"name"`
    Email string `db:"email"  json:"email"`
}

After (sortPriority: ["json", "yaml"]):

type User struct {
    ID    int    `json:"id"    yaml:"id"`
    Name  string `json:"name" yaml:"name" db:"name"`
    Email string `json:"email" db:"email"`
}

alphabetical mode - all keys sorted A->Z (after applying sortPriority).

Align Tags

Pads tag columns with spaces so values line up vertically. Only applied to consecutive fields - groups separated by blank lines are aligned independently.

Before:

type Address struct {
    Street  string `json:"street" yaml:"street" db:"street"`
    City    string `json:"city" yaml:"city" db:"city"`
    Country string `json:"country" yaml:"country" db:"country"`
    ZipCode string `json:"zip_code" yaml:"zip_code" db:"zip_code"`
}

After:

type Address struct {
    Street  string `json:"street"  yaml:"street"  db:"street"`
    City    string `json:"city"    yaml:"city"    db:"city"`
    Country string `json:"country" yaml:"country" db:"country"`
    ZipCode string `json:"zip_code" yaml:"zip_code" db:"zip_code"`
}

Fields separated by blank lines or comments are treated as separate groups and aligned independently.

Two settings control which tags get dedicated columns and how wide the gaps are allowed to grow - see alignColumnThreshold and alignMaxColumnGap.

Memory Layout Analysis

Analyses Go struct field ordering for memory efficiency and reports problems when the current order wastes space or is suboptimal for the garbage collector.

Diagnostics appear in the Problems panel and as squiggly underlines on the struct declaration line:

• "Memory: X bytes wasted in padding — reorder fields to save" - fields are ordered so the Go runtime must insert alignment padding between them. Placing larger-aligned fields first eliminates the wasted bytes.
• "Memory: pointer-bearing fields should precede non-pointer fields" - fields that contain pointers (slices, strings, maps, interfaces, raw pointers) should appear before plain scalars at the same alignment level to minimize the GC scan range, even when no padding would be saved.

An Optimize layout CodeLens button appears above any struct that would benefit:

Optimize layout (save 8 bytes)  |  Sort & Align Tags  |  Sort Tags  |  Align Tags
type UserProfile struct {

Clicking it rewrites the field order in-place, without touching tags or comments.

To suppress analysis for one struct, add a comment on the declaration line or anywhere inside the body:

type LegacyRecord struct { // go-struct-tags:no-reorder
    B byte
    X int64
}

// betteralign:ignore is also accepted as an alias:
type Another struct { // betteralign:ignore
    B byte
    X int64
}

The sort order follows four criteria (matching betteralign):

1. Zero-sized fields ([0]T) first — avoids end-of-struct address aliasing.
2. Higher alignment first — reduces inter-field padding.
3. Pointer-bearing fields before plain scalars — minimizes GC scan range.
4. Larger size first within the same alignment tier.

Normalize Tags

Both Sort and Align automatically normalize tags: strip extra spaces inside the backtick string and ensure a single space between each key:"value" pair.

// Before
Field string `   json:"id"      yaml:"id"   `

// After
Field string `json:"id" yaml:"id"`

Commands

All commands are available in the Command Palette (Ctrl+Shift+P / Cmd+Shift+P) under the Go Struct Tags Manager category.

• Sort Struct Field Tags - sort tags in the struct at cursor
• Align Struct Field Tags - align tags in the struct at cursor
• Sort & Align Struct Field Tags - sort then align in the struct at cursor
• Sort Struct Field Tags in File - apply sort to all structs in the file
• Align Struct Field Tags in File - apply alignment to all structs in the file
• Sort & Align Struct Field Tags in File - apply sort & align to all structs in the file
• Optimize Memory Layout - reorder fields of the struct at cursor for optimal memory alignment and GC scan range

Settings

• goStructTags.autoSortOnSave boolean - automatically sort tags on file save.
  Default: false.
• goStructTags.autoAlignOnSave boolean - automatically align tags on file save.
  Default: false.
• goStructTags.sortMode "smart" | "first-field" | "alphabetical" - how to determine canonical key order when sorting.
  Default: "smart".
• goStructTags.sortPriority string[] - tag keys that always come first, in the specified order, regardless of sortMode.
  Default: [].
• goStructTags.alignColumnThreshold number - minimum fraction of fields in an alignment group (0–1) for a tag to receive a dedicated column; tags below the threshold are appended without padding.
  Default: 0.5.
• goStructTags.alignMaxColumnGap number - maximum blank space (characters) that empty column slots may produce between two actual tag values; when the accumulated gap exceeds this limit the empty slots are dropped and replaced with a single space. Set to 0 to disable.
  Default: 24.
• goStructTags.colors.key string - override color for tag keys (e.g. json, yaml).
  Leave empty to use theme color.
• goStructTags.colors.value string - override color for tag values.
  Leave empty to use theme color.
• goStructTags.colors.option string - override color for tag options (after =).
  Leave empty to use theme color.
• goStructTags.colors.separator string - override color for tag separators (,).
  Leave empty to use theme color.
• goStructTags.memory.enable boolean - enable memory layout analysis: show diagnostics and CodeLens when struct field order wastes padding bytes or is suboptimal for GC scanning.
  Default: true.
• goStructTags.memory.severity "hint" | "information" | "warning" | "error" - diagnostic severity level for suboptimal struct field ordering.
  Default: "information".
• goStructTags.memory.architecture "amd64" | "arm64" | "386" - target architecture for memory layout calculations. Affects pointer size (8 bytes on amd64/arm64, 4 bytes on 386).
  Default: "amd64".

Example configuration

{
  // Always put json and yaml first, then sort the rest alphabetically
  "goStructTags.sortMode": "alphabetical",
  "goStructTags.sortPriority": ["json", "yaml"],

  // Auto-sort and align on every save
  "goStructTags.autoSortOnSave": true,
  "goStructTags.autoAlignOnSave": true
}

Color overrides accept any CSS color value (#rrggbb, rgba(...), theme token color, etc.).

Ignored Files

The extension silently skips the following files - no diagnostics, no CodeLens, no auto-sort or auto-align on save:

• Test files - any file whose name ends with _test.go.
• Generated files by name suffix - files ending with _generated.go, _gen.go, .gen.go, .pb.go, or .pb.gw.go.
• Generated files by comment - files whose first 10 lines contain a line matching Code generated .* DO NOT EDIT (the standard marker written by protoc-gen-go, go generate, stringer and similar tools).

Theme Compatibility

Syntax highlighting works via TextMate grammar injection into Go raw string literals. Colors depend entirely on how your active theme maps the underlying token scopes - the extension does not hardcode any colors by default.

Scope mapping used:

• Key (json, yaml, …) -> entity.name.tag
• Value (quoted string content) -> string.quoted.double
• Option key (before =) -> variable.other
• = operator -> keyword.operator
• Option value (after =) -> constant.numeric
• Separator (,) -> comment

Themes known to color all parts well: Monokai, One Dark Pro, Dracula, Tokyo Night, Catppuccin.

Themes with partial support (keys and values visible, options highlighted): Default Dark+, Default Light+.

If your theme shows missing or incorrect colors — for example all parts blending into the surrounding string color — configure overrides directly. The colors below match the Default Dark+ palette:

{
  "goStructTags.colors.key":       "#4EC9B0",
  "goStructTags.colors.value":     "#CE9178",
  "goStructTags.colors.option":    "#B5CEA8",
  "goStructTags.colors.separator": "#6A9955"
}

For Default Light+:

{
  "goStructTags.colors.key":       "#267F99",
  "goStructTags.colors.value":     "#A31515",
  "goStructTags.colors.option":    "#098658",
  "goStructTags.colors.separator": "#008000"
}