Go 1.26 Modernization: Adopt new language and stdlib features in azd

[spboyer]

Overview

With the migration to Go 1.26, several new language features, standard library additions, and performance improvements are available that can make azd faster, safer, and more readable.

Free Performance Wins (no code changes needed)

Simply building with Go 1.26 provides:

• Green Tea GC (default in 1.26): 10–40% GC overhead reduction
• Swiss Tables map implementation (1.24): 2–3% CPU reduction
• io.ReadAll optimization (1.26): ~2x faster, lower memory
• cgo overhead reduction (1.26): ~30% faster cgo calls
• Stack-allocated slice backing (1.25/1.26): fewer heap allocations

Current State

The codebase is already well-modernized:

• ✅ 266 usages of slices/maps packages
• ✅ Zero ioutil usages (fully migrated)
• ✅ errors.Join in use for multi-error scenarios
• ✅ context.WithoutCancel used where appropriate
• ✅ any used throughout (only 7 hand-written interface{} remain)

Sub-Issues

Quick Wins (trivial changes)

• Go 1.26: Run go fix automated modernizations #7082 — go fix automated modernizations
• Go 1.26: Replace math.Min and sort.Strings with builtins #7083 — Built-in min() + slices.Sort replacements
• Go 1.26: Use slices.Clone and slices.Sorted(maps.Keys(...)) #7084 — slices.Clone + slices.Sorted(maps.Keys(...)) one-liners
• Go 1.26: Range-over-int modernization #7088 — Range-over-int conversions

Standard Library Upgrades

• Go 1.26: Migrate sort.Slice to slices.SortFunc — account package #7085 — sort.Slice → slices.SortFunc (account package)
• Go 1.26: Migrate sort.Slice to slices.SortFunc — remaining packages #7086 — sort.Slice → slices.SortFunc (remaining packages)
• Go 1.26: Replace http.NewRequest with http.NewRequestWithContext #7087 — http.NewRequest → http.NewRequestWithContext

New Go 1.25/1.26 Feature Adoption

• Go 1.26: Adopt errors.AsType[T] — Azure API error paths #7090 — errors.AsType[T] — Azure API error paths
• Go 1.26: Adopt errors.AsType[T] — infra/provisioning #7091 — errors.AsType[T] — infra/provisioning
• Go 1.26: Adopt errors.AsType[T] — commands and actions #7092 — errors.AsType[T] — commands/actions
• Go 1.26: Adopt WaitGroup.Go for concurrent patterns #7093 — WaitGroup.Go for concurrent patterns
• Go 1.26: Create generic SyncMap[K, V] utility type #7089 — Generic SyncMap[K, V] utility type

Test Modernization

• Go 1.26: Test modernization — T.Context() adoption #7094 — T.Context() adoption
• Go 1.26: Test modernization — T.Chdir() adoption #7095 — T.Chdir() adoption

Future (require design discussion)

• omitzero JSON struct tags
• os.Root secure file access
• slog structured logging (309 sites)
• testing/synctest for retry/timeout tests

Analysis

Full analysis document with file-level details, code examples, and before/after comparisons is available in tmp/go-1.26-modernization-analysis.md in the repository.

References

• Go 1.24 Release Notes
• Go 1.25 Release Notes
• Go 1.26 Release Notes