cr

experimental/ast/syntax/doc.go

@@ -26,7 +26,7 @@ import (
 // Editions returns an iterator over all the editions in this package.
 func Editions() iter.Seq[Syntax] {
 	return func(yield func(Syntax) bool) {
-		for i := 0; i < totalEditions; i++ {
+		for i := range totalEditions {
 			if !yield(Syntax(i + int(Edition2023))) {
 				break
 			}

experimental/internal/taxa/noun.yaml

@@ -115,6 +115,8 @@
   - {name: Braces, string: "`{...}`"}
   - {name: Angles, string: "`<...>`"}
 
+  - {name: ReturnsParens, string: "`returns (...)`"}
+
   - {name: KeywordSyntax, string: "`syntax`"}
   - {name: KeywordEdition, string: "`edition`"}
   - {name: KeywordImport, string: "`import`"}

experimental/parser/diagnostics_internal.go

@@ -15,6 +15,8 @@
 package parser
 
 import (
+	"fmt"
+
 	"github.com/bufbuild/protocompile/experimental/ast"
 	"github.com/bufbuild/protocompile/experimental/internal/taxa"
 	"github.com/bufbuild/protocompile/experimental/report"
@@ -37,7 +39,10 @@ type errUnexpected struct {
 	// shown, but if it's not set, we call describe(what) to get a user-visible
 	// description.
 	want taxa.Set
-	got  any
+	// If set and want is empty, the snippet will repeat the "unexpected foo"
+	// text under the snippet.
+	repeatUnexpected bool
+	got              any
 }
 
 func (e errUnexpected) Diagnose(d *report.Diagnostic) {
@@ -49,20 +54,22 @@ func (e errUnexpected) Diagnose(d *report.Diagnostic) {
 		}
 	}
 
-	var message report.DiagnosticOption
+	var message string
 	if e.where.Subject() == taxa.Unknown {
-		message = report.Message("unexpected %v", got)
+		message = fmt.Sprintf("unexpected %v", got)
 	} else {
-		message = report.Message("unexpected %v %v", got, e.where)
+		message = fmt.Sprintf("unexpected %v %v", got, e.where)
 	}
 
 	snippet := report.Snippet(e.what)
 	if e.want.Len() > 0 {
 		snippet = report.Snippetf(e.what, "expected %v", e.want.Join("or"))
+	} else if e.repeatUnexpected {
+		snippet = report.Snippetf(e.what, "%v", message)
 	}
 
 	d.Apply(
-		message,
+		report.Message("%v", message),
 		snippet,
 		report.Snippetf(e.prev, "previous %v is here", e.where.Subject()),
 	)

experimental/parser/legalize_decl.go

@@ -127,9 +127,7 @@ func legalizeRange(p *parser, parent classified, decl ast.DeclRange) {
 			}
 		case ast.ExprKindPrefixed:
 			expr := expr.AsPrefixed()
-			//nolint:gocritic // Intentional single-case switch.
-			switch expr.Prefix() {
-			case ast.ExprPrefixMinus:
+			if expr.Prefix() == ast.ExprPrefixMinus {
 				lit := expr.Expr().AsLiteral()
 				if lit.Kind() != token.Number || strings.Contains(lit.Text(), ".") {
 					p.Error(errUnexpected{

experimental/parser/legalize_def.go

@@ -95,7 +95,8 @@ func legalizeTypeDefLike(p *parser, what taxa.Noun, def ast.DeclDef) {
 			err = errUnexpected{
 				what:  pc.Separator(),
 				where: taxa.Ident.In(),
-				want:  taxa.Ident.AsSet(),
+
+				repeatUnexpected: true,
 			}
 			return false
 		})
@@ -253,7 +254,7 @@ func legalizeMethod(p *parser, def ast.DeclDef) {
 		if sig.Inputs().Span().IsZero() {
 			def.MarkCorrupt()
 			p.Errorf("missing %v in %v", taxa.MethodIns, taxa.Method).Apply(
-				report.Snippetf(def.Name(), "expected type in %s after this", taxa.Parens),
+				report.Snippetf(def.Name(), "expected argument type in %s after this", taxa.Parens),
 			)
 		} else {
 			legalizeMethodParams(p, sig.Inputs(), taxa.MethodIns)
@@ -262,17 +263,21 @@ func legalizeMethod(p *parser, def ast.DeclDef) {
 		if sig.Outputs().Span().IsZero() {
 			def.MarkCorrupt()
 			var after report.Spanner
+			var expected taxa.Noun
 			switch {
 			case !sig.Returns().IsZero():
 				after = sig.Returns()
+				expected = taxa.Parens
 			case !sig.Inputs().IsZero():
 				after = sig.Inputs()
+				expected = taxa.ReturnsParens
 			default:
 				after = def.Name()
+				expected = taxa.ReturnsParens
 			}
 
 			p.Errorf("missing %v in %v", taxa.MethodOuts, taxa.Method).Apply(
-				report.Snippetf(after, "expected type in %s after this", taxa.Parens),
+				report.Snippetf(after, "expected return type in %s after this", expected),
 			)
 		} else {
 			legalizeMethodParams(p, sig.Outputs(), taxa.MethodOuts)

experimental/parser/legalize_option.go

@@ -157,6 +157,7 @@ func legalizeOptionValue(p *parser, decl report.Span, parent ast.ExprAny, value
 				}
 				fallthrough
 			default:
+				// TODO: generate a suggestion for this.
 				err.Apply(report.Helpf("break this %s into one per element", taxa.Option))
 			}
 

experimental/parser/parse_def.go

@@ -206,6 +206,9 @@ func (defOutputs) parse(p *defParser) report.Span {
 	// Note that the inputs and outputs of a method are parsed
 	// separately, so foo(bar) and foo returns (bar) are both possible.
 	returns := p.c.Next()
+	if p.args.Returns.IsZero() {
+		p.args.Returns = returns
+	}
 
 	var ty ast.TypeAny
 	list, err := p.Punct(p.c, "(", taxa.KeywordReturns.After())
@@ -220,7 +223,6 @@ func (defOutputs) parse(p *defParser) report.Span {
 	}
 
 	if p.outputs.IsZero() && p.outputTy.IsZero() {
-		p.args.Returns = returns
 		if !list.IsZero() {
 			p.outputs = list
 		} else {

internal/ext/mapsx/mapsx.go

@@ -30,5 +30,12 @@ func Keys[M ~map[K]V, K comparable, V any](m M) iter.Seq[K] {
 
 // KeySet returns a copy of m, with its values replaced with empty structs.
 func KeySet[M ~map[K]V, K comparable, V any](m M) map[K]struct{} {
-	return CollectSet(Keys(m))
+	// return CollectSet(Keys(m))
+	// Instead of going through an iterator, inline the loop so that
+	// we can preallocate and avoid rehashes.
+	keys := make(map[K]struct{}, len(m))
+	for k := range m {
+		keys[k] = struct{}{}
+	}
+	return keys
 }

internal/ext/stringsx/stringsx.go

@@ -26,7 +26,7 @@ import (
 	"github.com/bufbuild/protocompile/internal/iter"
 )
 
-// Rune returns the rune at the given index.
+// Rune returns the rune at the given byte index.
 //
 // Returns 0, false if out of bounds. Returns U+FFFD, false if rune decoding fails.
 func Rune[I slicesx.SliceIndex](s string, idx I) (rune, bool) {
@@ -37,7 +37,7 @@ func Rune[I slicesx.SliceIndex](s string, idx I) (rune, bool) {
 	return r, r != utf8.RuneError
 }
 
-// Rune returns the previous rune at the given index.
+// Rune returns the previous rune at the given byte index.
 //
 // Returns 0, false if out of bounds. Returns U+FFFD, false if rune decoding fails.
 func PrevRune[I slicesx.SliceIndex](s string, idx I) (rune, bool) {

internal/tools/go.mod

@@ -184,22 +184,12 @@ require (
 	go.uber.org/automaxprocs v1.6.0 // indirect
 	go.uber.org/multierr v1.11.0 // indirect
 	go.uber.org/zap v1.27.0 // indirect
-<<<<<<< HEAD
-	golang.org/x/exp v0.0.0-20250106191152-7588d65b2ba8 // indirect
-	golang.org/x/exp/typeparams v0.0.0-20241108190413-2d47ceb2692f // indirect
-	golang.org/x/mod v0.23.0 // indirect
-	golang.org/x/sync v0.11.0 // indirect
-	golang.org/x/sys v0.30.0 // indirect
-	golang.org/x/text v0.21.0 // indirect
-	google.golang.org/protobuf v1.36.4-0.20250116160514-2005adbe0cf6 // indirect
-=======
 	golang.org/x/exp/typeparams v0.0.0-20250210185358-939b2ce775ac // indirect
 	golang.org/x/mod v0.23.0 // indirect
 	golang.org/x/sync v0.11.0 // indirect
 	golang.org/x/sys v0.30.0 // indirect
 	golang.org/x/text v0.22.0 // indirect
 	google.golang.org/protobuf v1.36.4 // indirect
->>>>>>> origin/main
 	gopkg.in/ini.v1 v1.67.0 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect