fix: handle name import of src packages (#74)

Rename the package scope from internal package name to alias name.
Detect different packages in the same directory (forbidden by spec).
Update example to test named import.

example/pkg/_pkg8/src/github.com/foo/pkg/fromage/fromage.go

@@ -0,0 +1,7 @@
+package fromage
+
+import "fmt"
+
+func Hello() string {
+	return fmt.Sprint("Fromage!")
+}

example/pkg/_pkg8/src/github.com/foo/pkg/pkg.go

@@ -0,0 +1,17 @@
+package pkg
+
+import (
+	"fmt"
+
+	fr "github.com/foo/pkg/fromage"
+)
+
+func Here() string {
+	return "root"
+}
+
+func NewSample() func() string {
+	return func() string {
+		return fmt.Sprintf("%s %s", Here(), fr.Hello())
+	}
+}

example/pkg/_pkg9/src/github.com/foo/pkg/fromage/fromage.go

@@ -0,0 +1,7 @@
+package fromage
+
+import "fmt"
+
+func Hello() string {
+	return fmt.Sprint("Fromage!")
+}

example/pkg/_pkg9/src/github.com/foo/pkg/pkg.go

@@ -0,0 +1,17 @@
+package pkg
+
+import (
+	"fmt"
+
+	"github.com/foo/pkg/fromage"
+)
+
+func Here() string {
+	return "root"
+}
+
+func NewSample() func() string {
+	return func() string {
+		return fmt.Sprintf("%s %s", Here(), fromage.Hello())
+	}
+}

example/pkg/_pkg9/src/github.com/foo/pkg/pkgfalse.go

@@ -0,0 +1,17 @@
+package pkgfalse
+
+import (
+	"fmt"
+
+	"github.com/foo/pkg/fromage"
+)
+
+func HereNot() string {
+	return "root"
+}
+
+func NewSampleNot() func() string {
+	return func() string {
+		return fmt.Sprintf("%s %s", HereNot(), fromage.Here())
+	}
+}

example/pkg/pkg_test.go

@@ -59,6 +59,11 @@ func TestPackages(t *testing.T) {
 			goPath:   "./_pkg7/",
 			expected: "root vin cheese fromage",
 		},
+		{
+			desc:     "named subpackage",
+			goPath:   "./_pkg8/",
+			expected: "root Fromage!",
+		},
 	}
 
 	for _, test := range testCases {
@@ -96,3 +101,39 @@ func TestPackages(t *testing.T) {
 		})
 	}
 }
+
+func TestPackagesError(t *testing.T) {
+	testCases := []struct {
+		desc     string
+		goPath   string
+		expected string
+	}{
+		{
+			desc:     "different packages in the same directory",
+			goPath:   "./_pkg9/",
+			expected: "found packages pkg and pkgfalse in _pkg9/src/github.com/foo/pkg",
+		},
+	}
+
+	for _, test := range testCases {
+		test := test
+		t.Run(test.desc, func(t *testing.T) {
+
+			// Init go interpreter
+			i := interp.New(interp.Opt{
+				GoPath: test.goPath,
+			})
+			i.Use(stdlib.Value, stdlib.Type) // Use binary standard library
+
+			// Load pkg from sources
+			_, err := i.Eval(`import "github.com/foo/pkg"`)
+			if err == nil {
+				t.Fatalf("got no error, want %q", test.expected)
+			}
+
+			if err.Error() != test.expected {
+				t.Errorf("got %q, want %q", err.Error(), test.expected)
+			}
+		})
+	}
+}

interp/gta.go

@@ -100,7 +100,7 @@ func (interp *Interpreter) Gta(root *Node, rpath string) error {
 				}
 			} else {
 				// TODO: make sure we do not import a src package more than once
-				err = interp.importSrcFile(rpath, ipath)
+				err = interp.importSrcFile(rpath, ipath, name)
 				scope.sym[name] = &Symbol{typ: &Type{cat: SrcPkgT}, path: ipath}
 			}
 

interp/src.go

@@ -8,7 +8,7 @@ import (
 	"strings"
 )
 
-func (i *Interpreter) importSrcFile(rPath, path string) error {
+func (i *Interpreter) importSrcFile(rPath, path, alias string) error {
 	dir, rPath, err := pkgDir(i.GoPath, rPath, path)
 	if err != nil {
 		return err
@@ -23,6 +23,7 @@ func (i *Interpreter) importSrcFile(rPath, path string) error {
 	var rootNodes []*Node
 
 	var root *Node
+	var pkgName string
 
 	// Parse source files
 	for _, file := range files {
@@ -40,9 +41,15 @@ func (i *Interpreter) importSrcFile(rPath, path string) error {
 			return err
 		}
 
-		if _, root, err = i.ast(string(buf), name); err != nil {
+		var pname string
+		if pname, root, err = i.ast(string(buf), name); err != nil {
 			return err
 		}
+		if pkgName == "" {
+			pkgName = pname
+		} else if pkgName != pname {
+			return fmt.Errorf("found packages %s and %s in %s", pkgName, pname, dir)
+		}
 		rootNodes = append(rootNodes, root)
 
 		if i.AstDot {
@@ -64,6 +71,12 @@ func (i *Interpreter) importSrcFile(rPath, path string) error {
 		initNodes = append(initNodes, nodes...)
 	}
 
+	// Rename imported pkgName to alias if they are different
+	if pkgName != alias {
+		i.scope[alias] = i.scope[pkgName]
+		delete(i.scope, pkgName)
+	}
+
 	if i.NoRun {
 		return nil
 	}