Upgrades

[tooolbox]

Summary

This branch adds five new static analysis checks, a VS Code extension for in-template diagnostics, and CI for automated releases.

New checks

• Printf format validation — {{printf "%d" .Name}} where .Name is a string is now a type error. Format verbs are validated against argument types; %v is always accepted.
• template.Execute support — 2-arg Execute calls are now discovered and checked, not just ExecuteTemplate.
• Unused variable detection (W005) — {{$x := .Foo}} where $x is never referenced.
• Dead conditional branches (W006) — {{if true}}...{{else}}unreachable{{end}} and similar literal-constant conditions.
• Inconsistent sub-template types (W007) — warns when the same {{template "name"}} is called with incompatible data types from different call sites.

Improved existing checks

• Non-static ExecuteTemplate name resolution — call-graph tracing now resolves template names passed through function parameters, covering helper/wrapper patterns.
• ParseFiles and ParseGlob support — template initialization via ParseFiles(...) and ParseGlob(...) is now traced alongside the existing ParseFS support.
• Robust FuncMap type-checking — replaced fragile types.Eval approach with typesInfo.TypeOf for resolving FuncMap entries.
• Per-value nil guard tracking (W003) — pointer dereference warnings now track which specific value was guarded, not just whether any guard exists in scope.

VS Code extension

New vscode-go-template-check/ extension shows diagnostics inside template files (.gohtml, .tmpl, .gotmpl):

• Red squiggles on {{.MissingField}}
• Yellow squiggles for W001–W007 warnings
• Syntax highlighting for Go template directives
• Runs on save; prompts to install check-templates if not found

CI / Release automation

.github/workflows/release.yml — on GitHub release creation, builds check-templates binaries for linux/darwin/windows (amd64 + arm64) and packages the .vsix, uploading all as release assets.

What we didn't ship

• go/analysis analyzer / vettool integration — We built a go/analysis.Analyzer and wired it into the CLI as a go vet -vettool= backend. We reverted and then removed it entirely. The go/analysis framework doesn't provide access to EmbedFiles or cross-package deferred resolution, so it gives incomplete coverage compared to the standalone CLI — a false sense of security. The VS Code extension calls the CLI directly, which is the correct entry point.

Testing

• 40+ new txtar script tests covering all new error and warning cases
• Real on-disk fixture tests for cross-package scenarios (caught a bug with path handling on Windows)

Warning reference

Code	Category
W001	Non-static ExecuteTemplate name
W002	Unused template
W003	Unguarded pointer dereference
W004	Interface field access
W005	Unused variable
W006	Dead conditional branch
W007	Inconsistent sub-template types

Test plan

• go test ./... passes
• go tool check-templates ./... runs cleanly on a sample project
• VS Code extension loads and shows diagnostics in .gohtml files
• Release workflow runs on tag push and uploads assets