fix(go-runtime): remove duplicate positional information in errors (#…

…1064)

Fixes #1062

go-runtime/compile/errors.go

@@ -0,0 +1,40 @@
+package compile
+
+import (
+	"errors"
+	"fmt"
+	"go/ast"
+
+	"github.com/TBD54566975/ftl/backend/schema"
+)
+
+type Error struct {
+	Msg string
+	Pos schema.Position
+	Err error // Wrapped error, if any
+}
+
+func (e Error) Error() string { return fmt.Sprintf("%s: %s", e.Pos, e.Msg) }
+func (e Error) Unwrap() error { return e.Err }
+
+func errorf(node ast.Node, format string, args ...any) Error {
+	return Error{Msg: fmt.Sprintf(format, args...), Pos: goPosToSchemaPos(node.Pos())}
+}
+
+func wrapf(node ast.Node, err error, format string, args ...any) Error {
+	if format == "" {
+		format = "%s"
+	} else {
+		format += ": %s"
+	}
+	// Propagate existing error position if available
+	var pos schema.Position
+	if perr := (Error{}); errors.As(err, &perr) {
+		pos = perr.Pos
+		args = append(args, perr.Msg)
+	} else {
+		pos = goPosToSchemaPos(node.Pos())
+		args = append(args, err)
+	}
+	return Error{Msg: fmt.Sprintf(format, args...), Pos: pos, Err: err}
+}

go-runtime/compile/schema.go

@@ -61,15 +61,19 @@ func ExtractModuleSchema(dir string) (NativeNames, *schema.Module, error) {
 	for _, pkg := range pkgs {
 		if len(pkg.Errors) > 0 {
 			for _, perr := range pkg.Errors {
-				merr = append(merr, fmt.Errorf("%s: %w", pkg.PkgPath, perr))
+				if len(pkg.Syntax) > 0 {
+					merr = append(merr, wrapf(pkg.Syntax[0], perr, "%s", pkg.PkgPath))
+				} else {
+					merr = append(merr, fmt.Errorf("%s: %w", pkg.PkgPath, perr))
+				}
 			}
 		}
 		pctx := &parseContext{pkg: pkg, pkgs: pkgs, module: module, nativeNames: NativeNames{}, enums: enums{}}
 		for _, file := range pkg.Syntax {
 			err := goast.Visit(file, func(node ast.Node, next func() error) (err error) {
 				defer func() {
 					if err != nil {
-						err = fmt.Errorf("%s: %w", fset.Position(node.Pos()).String(), err)
+						err = wrapf(node, err, "")
 					}
 				}()
 				switch node := node.(type) {
@@ -149,14 +153,14 @@ func visitCallExpr(pctx *parseContext, node *ast.CallExpr) error {
 
 func parseCall(pctx *parseContext, node *ast.CallExpr) error {
 	if len(node.Args) != 3 {
-		return fmt.Errorf("%s: call must have exactly three arguments", goPosToSchemaPos(node.Pos()))
+		return errorf(node, "call must have exactly three arguments")
 	}
 	_, verbFn := deref[*types.Func](pctx.pkg, node.Args[1])
 	if verbFn == nil {
 		if sel, ok := node.Args[1].(*ast.SelectorExpr); ok {
-			return fmt.Errorf("call first argument must be a function but is an unresolved reference to %s.%s", sel.X, sel.Sel)
+			return errorf(node.Args[1], "call first argument must be a function but is an unresolved reference to %s.%s", sel.X, sel.Sel)
 		}
-		return fmt.Errorf("call first argument must be a function but is %T", node.Args[1])
+		return errorf(node.Args[1], "call first argument must be a function but is %T", node.Args[1])
 	}
 	if pctx.activeVerb == nil {
 		return nil
@@ -181,12 +185,12 @@ func parseConfigDecl(pctx *parseContext, node *ast.CallExpr, fn *types.Func) err
 			var err error
 			name, err = strconv.Unquote(literal.Value)
 			if err != nil {
-				return fmt.Errorf("%s: %w", goPosToSchemaPos(node.Pos()), err)
+				return wrapf(node, err, "")
 			}
 		}
 	}
 	if name == "" {
-		return fmt.Errorf("%s: config and secret declarations must have a single string literal argument", goPosToSchemaPos(node.Pos()))
+		return errorf(node, "config and secret declarations must have a single string literal argument")
 	}
 	index := node.Fun.(*ast.IndexExpr) //nolint:forcetypeassert
 
@@ -229,12 +233,12 @@ func visitFile(pctx *parseContext, node *ast.File) error {
 		switch dir := dir.(type) {
 		case *directiveModule:
 			if dir.Name != pctx.pkg.Name {
-				return fmt.Errorf("%s: FTL module name %q does not match Go package name %q", dir, dir.Name, pctx.pkg.Name)
+				return errorf(node, "%s: FTL module name %q does not match Go package name %q", dir, dir.Name, pctx.pkg.Name)
 			}
 			pctx.module.Name = dir.Name
 
 		default:
-			return fmt.Errorf("%s: invalid directive", dir)
+			return errorf(node, "%s: invalid directive", dir)
 		}
 	}
 	return nil
@@ -442,7 +446,7 @@ func visitFuncDecl(pctx *parseContext, node *ast.FuncDecl) (verb *schema.Verb, e
 	results := sig.Results()
 	reqt, respt, err := checkSignature(sig)
 	if err != nil {
-		return nil, err
+		return nil, wrapf(node, err, "")
 	}
 	var req schema.Type
 	if reqt != nil {
@@ -688,7 +692,7 @@ func visitType(pctx *parseContext, node ast.Node, tnode types.Type) (schema.Type
 			return &schema.Float{Pos: goPosToSchemaPos(node.Pos())}, nil
 
 		default:
-			return nil, fmt.Errorf("unsupported basic type %s", underlying)
+			return nil, errorf(node, "unsupported basic type %s", underlying)
 		}
 
 	case *types.Struct:
@@ -726,10 +730,10 @@ func visitType(pctx *parseContext, node ast.Node, tnode types.Type) (schema.Type
 		if underlying.String() == "any" {
 			return &schema.Any{Pos: goPosToSchemaPos(node.Pos())}, nil
 		}
-		return nil, fmt.Errorf("%s: unsupported type %T", goPosToSchemaPos(node.Pos()), node)
+		return nil, errorf(node, "unsupported type %T", node)
 
 	default:
-		return nil, fmt.Errorf("%s: unsupported type %T", goPosToSchemaPos(node.Pos()), node)
+		return nil, errorf(node, "unsupported type %T", node)
 	}
 }
 

go-runtime/compile/schema_test.go

@@ -3,6 +3,8 @@ package compile
 import (
 	"go/ast"
 	"go/types"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
 
@@ -175,3 +177,9 @@ func TestParseBasicTypes(t *testing.T) {
 func normaliseString(s string) string {
 	return strings.TrimSpace(strings.Join(slices.Map(strings.Split(s, "\n"), strings.TrimSpace), "\n"))
 }
+
+func TestErrorReporting(t *testing.T) {
+	pwd, _ := os.Getwd()
+	_, _, err := ExtractModuleSchema("testdata/failing")
+	assert.EqualError(t, err, filepath.Join(pwd, `testdata/failing/failing.go`)+`:15:2: call must have exactly three arguments`)
+}

go-runtime/compile/testdata/failing/failing.go

@@ -0,0 +1,17 @@
+//ftl:module failing
+package failing
+
+import (
+	"context"
+
+	"github.com/TBD54566975/ftl/go-runtime/ftl"
+)
+
+type Request struct{}
+type Response struct{}
+
+//ftl:verb
+func FailingVerb(ctx context.Context, req Request) (Response, error) {
+	ftl.Call(ctx, "failing", "failingVerb", req)
+	return Response{}, nil
+}