Adding upstream version 1.17.13.upstream/1.17.13upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 180 insertions, 0 deletions

diff --git a/src/go/parser/resolver_test.go b/src/go/parser/resolver_test.go
new file mode 100644
index 0000000..625c009
--- /dev/null
+++ b/src/go/parser/resolver_test.go
@@ -0,0 +1,180 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package parser
+
+import (
+	"fmt"
+	"go/ast"
+	"go/internal/typeparams"
+	"go/scanner"
+	"go/token"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+// TestResolution checks that identifiers are resolved to the declarations
+// annotated in the source, by comparing the positions of the resulting
+// Ident.Obj.Decl to positions marked in the source via special comments.
+//
+// In the test source, any comment prefixed with '=' or '@' (or both) marks the
+// previous token position as the declaration ('=') or a use ('@') of an
+// identifier. The text following '=' and '@' in the comment string is the
+// label to use for the location.  Declaration labels must be unique within the
+// file, and use labels must refer to an existing declaration label. It's OK
+// for a comment to denote both the declaration and use of a label (e.g.
+// '=@foo'). Leading and trailing whitespace is ignored. Any comment not
+// beginning with '=' or '@' is ignored.
+func TestResolution(t *testing.T) {
+	dir := filepath.Join("testdata", "resolution")
+	fis, err := os.ReadDir(dir)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, fi := range fis {
+		t.Run(fi.Name(), func(t *testing.T) {
+			fset := token.NewFileSet()
+			path := filepath.Join(dir, fi.Name())
+			src := readFile(path) // panics on failure
+			var mode Mode
+			if strings.HasSuffix(path, ".go2") {
+				if !typeparams.Enabled {
+					t.Skip("type params are not enabled")
+				}
+			} else {
+				mode |= typeparams.DisallowParsing
+			}
+			file, err := ParseFile(fset, path, src, mode)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			// Compare the positions of objects resolved during parsing (fromParser)
+			// to those annotated in source comments (fromComments).
+
+			handle := fset.File(file.Package)
+			fromParser := declsFromParser(file)
+			fromComments := declsFromComments(handle, src)
+
+			pos := func(pos token.Pos) token.Position {
+				p := handle.Position(pos)
+				// The file name is implied by the subtest, so remove it to avoid
+				// clutter in error messages.
+				p.Filename = ""
+				return p
+			}
+			for k, want := range fromComments {
+				if got := fromParser[k]; got != want {
+					t.Errorf("%s resolved to %s, want %s", pos(k), pos(got), pos(want))
+				}
+				delete(fromParser, k)
+			}
+			// What remains in fromParser are unexpected resolutions.
+			for k, got := range fromParser {
+				t.Errorf("%s resolved to %s, want no object", pos(k), pos(got))
+			}
+		})
+	}
+}
+
+// declsFromParser walks the file and collects the map associating an
+// identifier position with its declaration position.
+func declsFromParser(file *ast.File) map[token.Pos]token.Pos {
+	objmap := map[token.Pos]token.Pos{}
+	ast.Inspect(file, func(node ast.Node) bool {
+		// Ignore blank identifiers to reduce noise.
+		if ident, _ := node.(*ast.Ident); ident != nil && ident.Obj != nil && ident.Name != "_" {
+			objmap[ident.Pos()] = ident.Obj.Pos()
+		}
+		return true
+	})
+	return objmap
+}
+
+// declsFromComments looks at comments annotating uses and declarations, and
+// maps each identifier use to its corresponding declaration. See the
+// description of these annotations in the documentation for TestResolution.
+func declsFromComments(handle *token.File, src []byte) map[token.Pos]token.Pos {
+	decls, uses := positionMarkers(handle, src)
+
+	objmap := make(map[token.Pos]token.Pos)
+	// Join decls and uses on name, to build the map of use->decl.
+	for name, posns := range uses {
+		declpos, ok := decls[name]
+		if !ok {
+			panic(fmt.Sprintf("missing declaration for %s", name))
+		}
+		for _, pos := range posns {
+			objmap[pos] = declpos
+		}
+	}
+	return objmap
+}
+
+// positionMarkers extracts named positions from the source denoted by comments
+// prefixed with '=' (declarations) and '@' (uses): for example '@foo' or
+// '=@bar'. It returns a map of name->position for declarations, and
+// name->position(s) for uses.
+func positionMarkers(handle *token.File, src []byte) (decls map[string]token.Pos, uses map[string][]token.Pos) {
+	var s scanner.Scanner
+	s.Init(handle, src, nil, scanner.ScanComments)
+	decls = make(map[string]token.Pos)
+	uses = make(map[string][]token.Pos)
+	var prev token.Pos // position of last non-comment, non-semicolon token
+
+scanFile:
+	for {
+		pos, tok, lit := s.Scan()
+		switch tok {
+		case token.EOF:
+			break scanFile
+		case token.COMMENT:
+			name, decl, use := annotatedObj(lit)
+			if len(name) > 0 {
+				if decl {
+					if _, ok := decls[name]; ok {
+						panic(fmt.Sprintf("duplicate declaration markers for %s", name))
+					}
+					decls[name] = prev
+				}
+				if use {
+					uses[name] = append(uses[name], prev)
+				}
+			}
+		case token.SEMICOLON:
+			// ignore automatically inserted semicolon
+			if lit == "\n" {
+				continue scanFile
+			}
+			fallthrough
+		default:
+			prev = pos
+		}
+	}
+	return decls, uses
+}
+
+func annotatedObj(lit string) (name string, decl, use bool) {
+	if lit[1] == '*' {
+		lit = lit[:len(lit)-2] // strip trailing */
+	}
+	lit = strings.TrimSpace(lit[2:])
+
+scanLit:
+	for idx, r := range lit {
+		switch r {
+		case '=':
+			decl = true
+		case '@':
+			use = true
+		default:
+			name = lit[idx:]
+			break scanLit
+		}
+	}
+	return
+}