go/types: add tests for new Go 2 number literals

This CL ensures that go/types can now handle the new
Go 2 number literals. The relevant changes enabling
them in go/types were made in go/constant in the CL
https://golang.org/cl/160239.

R=Go1.13

Updates golang#12711.
Updates golang#19308.
Updates golang#28493.
Updates golang#29008.

Change-Id: I45c1387198fac94769ac59c5301d86b4e1a1ff98
Reviewed-on: https://go-review.googlesource.com/c/160240
Reviewed-by: Russ Cox <rsc@golang.org>

src/go/types/check_test.go

@@ -88,6 +88,7 @@ var tests = [][]string{
 	{"testdata/stmt1.src"},
 	{"testdata/gotos.src"},
 	{"testdata/labels.src"},
+	{"testdata/literals.src"},
 	{"testdata/issues.src"},
 	{"testdata/blank.src"},
 	{"testdata/issue25008b.src", "testdata/issue25008a.src"}, // order (b before a) is crucial!

src/go/types/stdlib_test.go

@@ -155,7 +155,6 @@ func TestStdTest(t *testing.T) {
 	}
 
 	testTestDir(t, filepath.Join(runtime.GOROOT(), "test"),
-		"literal2.go",    // go/scanner cannot handle new number literals yet - TODO(gri) enable once fixed
 		"cmplxdivide.go", // also needs file cmplxdivide1.go - ignore
 	)
 }

src/go/types/testdata/literals.src

@@ -0,0 +1,111 @@
+// Copyright 2019 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.
+
+// This file tests various representations of literals
+// and compares them with literals or constant expressions
+// of equal values.
+
+package literals
+
+func _() {
+	// 0-octals
+	assert(0_123 == 0123)
+	assert(0123_456 == 0123456)
+
+	// decimals
+	assert(1_234 == 1234)
+	assert(1_234_567 == 1234567)
+
+	// hexadecimals
+	assert(0X_0 == 0)
+	assert(0X_1234 == 0x1234)
+	assert(0X_CAFE_f00d == 0xcafef00d)
+
+	// octals
+	assert(0o0 == 0)
+	assert(0o1234 == 01234)
+	assert(0o01234567 == 01234567)
+
+	assert(0O0 == 0)
+	assert(0O1234 == 01234)
+	assert(0O01234567 == 01234567)
+
+	assert(0o_0 == 0)
+	assert(0o_1234 == 01234)
+	assert(0o0123_4567 == 01234567)
+
+	assert(0O_0 == 0)
+	assert(0O_1234 == 01234)
+	assert(0O0123_4567 == 01234567)
+
+	// binaries
+	assert(0b0 == 0)
+	assert(0b1011 == 0xb)
+	assert(0b00101101 == 0x2d)
+
+	assert(0B0 == 0)
+	assert(0B1011 == 0xb)
+	assert(0B00101101 == 0x2d)
+
+	assert(0b_0 == 0)
+	assert(0b10_11 == 0xb)
+	assert(0b_0010_1101 == 0x2d)
+
+	// decimal floats
+	assert(1_2_3. == 123.)
+	assert(0_123. == 123.)
+
+	assert(0_0e0 == 0.)
+	assert(1_2_3e0 == 123.)
+	assert(0_123e0 == 123.)
+
+	assert(0e-0_0 == 0.)
+	assert(1_2_3E+0 == 123.)
+	assert(0123E1_2_3 == 123e123)
+
+	assert(0.e+1 == 0.)
+	assert(123.E-1_0 == 123e-10)
+	assert(01_23.e123 == 123e123)
+
+	assert(.0e-1 == .0)
+	assert(.123E+10 == .123e10)
+	assert(.0123E123 == .0123e123)
+
+	assert(1_2_3.123 == 123.123)
+	assert(0123.01_23 == 123.0123)
+
+	// hexadecimal floats
+	assert(0x0.p+0 == 0.)
+	assert(0Xdeadcafe.p-10 == 0xdeadcafe/1024.0)
+	assert(0x1234.P84 == 0x1234000000000000000000000)
+
+	assert(0x.1p-0 == 1./16)
+	assert(0X.deadcafep4 == 1.0*0xdeadcafe/0x10000000)
+	assert(0x.1234P+12 == 1.0*0x1234/0x10)
+
+	assert(0x0p0 == 0.)
+	assert(0Xdeadcafep+1 == 0x1bd5b95fc)
+	assert(0x1234P-10 == 0x1234/1024.0)
+
+	assert(0x0.0p0 == 0.)
+	assert(0Xdead.cafep+1 == 1.0*0x1bd5b95fc/0x10000)
+	assert(0x12.34P-10 == 1.0*0x1234/0x40000)
+
+	assert(0Xdead_cafep+1 == 0xdeadcafep+1)
+	assert(0x_1234P-10 == 0x1234p-10)
+
+	assert(0X_dead_cafe.p-10 == 0xdeadcafe.p-10)
+	assert(0x12_34.P1_2_3 == 0x1234.p123)
+
+	assert(1_234i == 1234i)
+	assert(1_234_567i == 1234567i)
+
+	assert(0.i == 0i)
+	assert(123.i == 123i)
+	assert(0123.i == 123i)
+
+	assert(0.e+1i == 0i)
+	assert(123.E-1_0i == 123e-10i)
+	assert(01_23.e123i == 123e123i)
+}