Type computation tests (#511)

* test of a little type computation

* another test and some bug fixes

executable_semantics/testdata/tuple5.golden

@@ -1,4 +1,4 @@
 8: type error in pattern variable
-expected: (x = Int@2, y = Int@3)
-actual: (y = Int@0, x = Int@1)
+expected: (x = Int, y = Int)
+actual: (y = Int, x = Int)
 EXIT CODE: 255

executable_semantics/testdata/tuple_equality3.golden

@@ -1,4 +1,4 @@
 8: type error in ==
-expected: (0 = Int@2, 1 = Int@3)
-actual: (0 = Int@5)
+expected: (0 = Int, 1 = Int)
+actual: (0 = Int)
 EXIT CODE: 255

executable_semantics/testdata/type_compute.6c

@@ -0,0 +1,12 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+fn Id(Type: t) => t;
+
+// Test non-trivial type expression in variable declaration statement.
+
+fn main() -> Int {
+  var Id(Int): x = 0;
+  return x;
+}

executable_semantics/testdata/type_compute.golden

@@ -0,0 +1 @@
+result: 0

executable_semantics/testdata/type_compute2.6c

@@ -0,0 +1,11 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+fn Id(Type: t) => t;
+
+// Test non-trivial type expression in return type.
+
+fn main() -> Id(Int) {
+  return 0;
+}

executable_semantics/testdata/type_compute2.golden

@@ -0,0 +1 @@
+result: 0

executable_semantics/testdata/type_compute3.6c

@@ -0,0 +1,15 @@
+// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
+// Exceptions. See /LICENSE for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+fn Id(Type: t) => t;
+
+// Test non-trivial type expression in parameter type.
+
+fn f(Id(Int): x) -> Int {
+  return x;
+}
+
+fn main() -> Int {
+  return f(0);
+}

executable_semantics/testdata/type_compute3.golden

@@ -0,0 +1 @@
+result: 0