feat(lint): add render function lint signature

gnovm/cmd/gno/lint.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"flag"
 	"fmt"
+	"go/types"
 	goio "io"
 	"io/fs"
 	"path/filepath"
@@ -256,7 +257,7 @@ func execLint(cmd *lintCmd, args []string, io commands.IO) error {
 			if cmd.autoGnomod {
 				tcmode = gno.TCLatestRelaxed
 			}
-			errs := lintTypeCheck(io, dir, mpkg, gno.TypeCheckOptions{
+			tcPkg, errs := lintTypeCheck(io, dir, mpkg, gno.TypeCheckOptions{
 				Getter:     newProdGnoStore(),
 				TestGetter: newTestGnoStore(true),
 				Mode:       tcmode,
@@ -268,6 +269,14 @@ func execLint(cmd *lintCmd, args []string, io commands.IO) error {
 				return
 			}
 
+			// ensure the 'Render' function is correct
+			err = lintRenderSignature(io, tcPkg)
+			if err != nil {
+				// io.ErrPrintln(err) printed above.
+				hasError = true
+				return
+			}
+
 			// Construct machine for testing.
 			tm := test.Machine(newProdGnoStore(), goio.Discard, pkgPath, false)
 			defer tm.Release()
@@ -368,10 +377,11 @@ func lintTypeCheck(
 	mpkg *std.MemPackage,
 	opts gno.TypeCheckOptions) (
 	// Results:
+	tcPkg *types.Package,
 	lerr error,
 ) {
 	// gno.TypeCheckMemPackage(mpkg, testStore).
-	_, tcErrs := gno.TypeCheckMemPackage(mpkg, opts)
+	tcPkg, tcErrs := gno.TypeCheckMemPackage(mpkg, opts)
 
 	// Print errors, and return the first unexpected error.
 	errors := multierr.Errors(tcErrs)
@@ -390,3 +400,59 @@ func lintTargetName(pkg *packages.Package) string {
 
 	return tryRelativizePath(pkg.Dir)
 }
+
+// lintRenderSignature checks if a Render function in the package has the
+// expected signature: func Render(string) string
+// Methods are ignored (e.g. func (t *Type) Render()).
+// Returns error if the signature is incorrect.
+func lintRenderSignature(io commands.IO, pkg *types.Package) error {
+	if pkg == nil {
+		return nil
+	}
+
+	o := pkg.Scope().Lookup("Render")
+	if o == nil {
+		return nil
+	}
+
+	var (
+		stringType = "string"
+		errPrintln = func() error {
+			err := fmt.Errorf("the 'Render' function signature is incorrect for the '%s' package. the signature must be of the form: func Render(string) string", pkg.Name())
+			fmt.Fprintln(io.Err(), gnoIssue{
+				Code:       gnoParserError,
+				Msg:        err.Error(),
+				Confidence: 1,
+				Location:   pkg.Path(),
+			})
+			return err
+		}
+		isSingleString = func(t *types.Tuple) bool {
+			return t != nil &&
+				t.Len() == 1 &&
+				t.At(0) != nil &&
+				t.At(0).Type().String() == stringType
+		}
+	)
+
+	fn, ok := o.(*types.Func)
+	if !ok {
+		return nil
+	}
+
+	s, ok := fn.Type().(*types.Signature)
+	if !ok {
+		return nil
+	}
+
+	if s.Recv() != nil {
+		return nil
+	}
+
+	switch {
+	case !isSingleString(s.Params()), !isSingleString(s.Results()):
+		return errPrintln()
+	default:
+		return nil
+	}
+}

gnovm/cmd/gno/lint_test.go

@@ -87,6 +87,42 @@ func TestLintApp(t *testing.T) {
 			// stderr / stdout should be empty; the init function and statements
 			// should not be executed
 		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_invalid1",
+			simulateExternalRepo: true,
+			stderrShouldBe:       "gno.land/t/render_invalid1: the 'Render' function signature is incorrect for the 'main' package. the signature must be of the form: func Render(string) string (code=gnoParserError)\n",
+			errShouldBe:          "exit code: 1",
+		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_invalid2",
+			simulateExternalRepo: true,
+			stderrShouldBe:       "gno.land/t/render_invalid2: the 'Render' function signature is incorrect for the 'main' package. the signature must be of the form: func Render(string) string (code=gnoParserError)\n",
+			errShouldBe:          "exit code: 1",
+		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_invalid3",
+			simulateExternalRepo: true,
+			stderrShouldBe:       "gno.land/t/render_invalid3: the 'Render' function signature is incorrect for the 'main' package. the signature must be of the form: func Render(string) string (code=gnoParserError)\n",
+			errShouldBe:          "exit code: 1",
+		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_valid1",
+			simulateExternalRepo: true,
+		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_valid2",
+			simulateExternalRepo: true,
+		},
+		{
+			args:                 []string{"lint", "."},
+			testDir:              "../../tests/integ/render_valid3",
+			simulateExternalRepo: true,
+		},
 
 		// TODO: 'gno mod' is valid?
 		// TODO: are dependencies valid?

gnovm/cmd/gno/test.go

@@ -308,7 +308,7 @@ func execTest(cmd *testCmd, args []string, io commands.IO) error {
 		startedAt := time.Now()
 		didPanic = catchPanic(pkg.Dir, pkgPath, io.Err(), func() {
 			if mod == nil || !mod.Ignore {
-				errs := lintTypeCheck(io, pkg.Dir, mpkg, gno.TypeCheckOptions{
+				_, errs := lintTypeCheck(io, pkg.Dir, mpkg, gno.TypeCheckOptions{
 					Getter:     opts.TestStore,
 					TestGetter: opts.TestStore,
 					Mode:       gno.TCLatestRelaxed,

gnovm/tests/integ/render_invalid1/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_invalid1"

gnovm/tests/integ/render_invalid1/main.gno

@@ -0,0 +1,7 @@
+package main
+
+// Invalid 'Render' function: wrong parameter (int instead of string)
+
+func Render(input int) string {
+	return "hello"
+}

gnovm/tests/integ/render_invalid2/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_invalid2"

gnovm/tests/integ/render_invalid2/main.gno

@@ -0,0 +1,7 @@
+package main
+
+// Invalid 'Render' function: wrong return type (int instead of string)
+
+func Render(input string) int {
+	return 9001
+}

gnovm/tests/integ/render_invalid3/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_invalid3"

gnovm/tests/integ/render_invalid3/main.gno

@@ -0,0 +1,7 @@
+package main
+
+// Invalid 'Render' function: too many parameters (2 instead of 1)
+
+func Render(input string, extra int) string {
+	return input
+}

gnovm/tests/integ/render_valid1/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_valid1"

gnovm/tests/integ/render_valid1/main.gno

@@ -0,0 +1,5 @@
+package main
+
+// No 'Render' function is considered as valid
+
+func Random() {}

gnovm/tests/integ/render_valid2/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_valid2"

gnovm/tests/integ/render_valid2/main.gno

@@ -0,0 +1,9 @@
+package main
+
+type Test struct{}
+
+// 'Render' method does not need to follow the signature of the pkg scope 'Render' function
+
+func (t *Test) Render(input int) int {
+	return input
+}

gnovm/tests/integ/render_valid3/gnomod.toml

@@ -0,0 +1 @@
+module = "gno.land/t/render_valid3"

gnovm/tests/integ/render_valid3/main.gno

@@ -0,0 +1,7 @@
+package main
+
+// Valid 'Render' pkg scope function
+
+func Render(input string) string {
+	return input
+}