[dev.inline] cmd/compile/internal/syntax: add tests for //line directives

Change-Id: I77dc73bfe79e43bbadf85d7eb3c5f8990ec72023
Reviewed-on: https://go-review.googlesource.com/34248
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/syntax/parser.go

@@ -47,7 +47,7 @@ func (p *parser) init(filename string, src io.Reader, errh ErrorHandler, pragh P
 		},
 		func(line, col uint, text string) {
 			if strings.HasPrefix(text, "line ") {
-				p.updateBase(line, col, text[5:])
+				p.updateBase(line, col+5, text[5:])
 			}
 			if pragh != nil {
 				p.pragma |= pragh(p.pos_at(line, col), text)
@@ -67,7 +67,7 @@ func (p *parser) updateBase(line, col uint, text string) {
 	// Want to use LastIndexByte below but it's not defined in Go1.4 and bootstrap fails.
 	i := strings.LastIndex(text, ":") // look from right (Windows filenames may contain ':')
 	if i < 0 {
-		return
+		return // ignore (not a line directive)
 	}
 	nstr := text[i+1:]
 	n, err := strconv.Atoi(nstr)

src/cmd/compile/internal/syntax/parser_test.go

@@ -182,3 +182,47 @@ func TestParseFile(t *testing.T) {
 		t.Errorf("got %v; want first error %v", err, first)
 	}
 }
+
+func TestLineDirectives(t *testing.T) {
+	for _, test := range []struct {
+		src, msg  string
+		filename  string
+		line, col uint
+	}{
+		// test validity of //line directive
+		{`//line :`, "invalid line number: ", "", 1, 8},
+		{`//line :x`, "invalid line number: x", "", 1, 8},
+		{`//line foo :`, "invalid line number: ", "", 1, 12},
+		{`//line foo:123abc`, "invalid line number: 123abc", "", 1, 11},
+		{`/**///line foo:x`, "invalid line number: x", "", 1, 15},
+		{`//line foo:0`, "invalid line number: 0", "", 1, 11},
+		{fmt.Sprintf(`//line foo:%d`, lineMax+1), fmt.Sprintf("invalid line number: %d", lineMax+1), "", 1, 11},
+
+		// test effect of //line directive on (relative) position information
+		{"//line foo:123\n   foo", "syntax error: package statement must be first", "foo", 123, 3},
+		{"//line foo:123\n//line bar:345\nfoo", "syntax error: package statement must be first", "bar", 345, 0},
+	} {
+		_, err := ParseBytes("", []byte(test.src), nil, nil, 0)
+		if err == nil {
+			t.Errorf("%s: no error reported", test.src)
+			continue
+		}
+		perr, ok := err.(Error)
+		if !ok {
+			t.Errorf("%s: got %v; want parser error", test.src, err)
+			continue
+		}
+		if msg := perr.Msg; msg != test.msg {
+			t.Errorf("%s: got msg = %q; want %q", test.src, msg, test.msg)
+		}
+		if filename := perr.Pos.RelFilename(); filename != test.filename {
+			t.Errorf("%s: got filename = %q; want %q", test.src, filename, test.filename)
+		}
+		if line := perr.Pos.RelLine(); line != test.line {
+			t.Errorf("%s: got line = %d; want %d", test.src, line, test.line)
+		}
+		if col := perr.Pos.Col(); col != test.col {
+			t.Errorf("%s: got col = %d; want %d", test.src, col, test.col)
+		}
+	}
+}

src/cmd/compile/internal/syntax/scanner_test.go

@@ -322,15 +322,6 @@ func TestScanErrors(t *testing.T) {
 		{`var s string = "\x"`, "non-hex character in escape sequence: \"", 1, 18},
 		{`return "\Uffffffff"`, "escape sequence is invalid Unicode code point", 1, 18},
 
-		// TODO(gri) move these test cases into an appropriate parser test
-		// {`//line :`, "invalid line number: ", 1, 8},
-		// {`//line :x`, "invalid line number: x", 1, 8},
-		// {`//line foo :`, "invalid line number: ", 1, 12},
-		// {`//line foo:123abc`, "invalid line number: 123abc", 1, 11},
-		// {`/**///line foo:x`, "invalid line number: x", 1, 15},
-		// {`//line foo:0`, "invalid line number: 0", 1, 11},
-		// {fmt.Sprintf(`//line foo:%d`, lineMax+1), fmt.Sprintf("invalid line number: %d", lineMax+1), 1, 11},
-
 		// former problem cases
 		{"package p\n\n\xef", "invalid UTF-8 encoding", 3, 0},
 	} {