Reorganize tests into dirs and rename numbered tests (#825)

There's a small update to update_checks.py to handle the recursive directories. Also, I'm only using one level of nesting in this PR but really no reason we can't do more. I'm just not sure what clustering is best right now.

As a pattern, I'm trying to name all failing tests `fail_*.carbon`.

executable_semantics/testdata/basic_syntax/choice.carbon

@@ -0,0 +1,48 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+choice Ints {
+  None,
+  One(i32),
+  Two(i32,i32)
+}
+
+fn main() -> i32 {
+  var x: auto = Ints.None();
+  var y: auto = Ints.One(42);
+  var n: auto = 0;
+  match (y) {
+    case Ints.None =>
+      n = n + 2;
+    case Ints.One(x: auto) =>
+      n = x + 1 - 42;
+    case Ints.Two(a: auto, b: auto) =>
+      n = 2;
+  }
+  match (x) {
+    case Ints.One(x: auto) =>
+      n = x + 2;
+    case Ints.None() =>
+      n = n - 1;
+    case Ints.Two(x: auto, y: auto) =>
+      n = 5;
+  }
+  return n;
+}
+
+// Test some alternate syntaxes
+choice MoreInts {
+  None(),
+  One(i32),
+  Two(i32,i32),
+}

executable_semantics/testdata/basic_syntax/fail_invalid_char.carbon

@@ -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
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/executable_semantics/testdata/basic_syntax/fail_invalid_char.carbon:12: invalid character '\xEF' in source file.
+
+�

executable_semantics/testdata/basic_syntax/fail_missing_var.carbon

@@ -0,0 +1,18 @@
+// 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
+//
+// RUN: not executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: not executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: COMPILATION ERROR: {{.*}}/executable_semantics/testdata/basic_syntax/fail_missing_var.carbon:16: syntax error, unexpected COLON
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  // error
+  x : i32;
+  return 1;
+}

executable_semantics/testdata/basic_syntax/next.carbon

@@ -0,0 +1,18 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main () -> i32
+{
+  var x: i32 = 0;
+  return x;
+}

executable_semantics/testdata/basic_syntax/placeholder_variable.carbon

@@ -0,0 +1,17 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  var _: auto = 1;
+  return 0;
+}

executable_semantics/testdata/basic_syntax/print.carbon

@@ -0,0 +1,19 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: Hello world!
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  var s: auto = "Hello world!\n";
+  Print(s);
+  return 0;
+}

executable_semantics/testdata/basic_syntax/record.carbon

@@ -0,0 +1,18 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  var t2: (.x = i32, .y = i32) = (.x = 2, .y = 5);
+  t2.y = 3;
+  return t2.y - t2.x - 1; // 3 - 2 - 1
+}

executable_semantics/testdata/basic_syntax/star.carbon

@@ -0,0 +1,25 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+// Never actually called, so this only tests typechecking and semantic analysis.
+fn F(n: i32, p: i32*, q: i32***) -> i32* {
+  var a: i32 = n * *p;
+  var b: i32 = a*n;
+  *p = b*(*p);
+  **q = p;
+  return **q;
+}
+
+fn main() -> i32 {
+  return 0;
+}

executable_semantics/testdata/basic_syntax/var_tuple.carbon

@@ -0,0 +1,17 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  var (x: auto, y: auto) = (2, 3);
+  return y - x - 1;
+}

executable_semantics/testdata/basic_syntax/zero.carbon

@@ -0,0 +1,16 @@
+// 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
+//
+// RUN: executable_semantics %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes=false %s
+// RUN: executable_semantics --trace %s 2>&1 | \
+// RUN:   FileCheck --match-full-lines --allow-unused-prefixes %s
+// AUTOUPDATE: executable_semantics %s
+// CHECK: result: 0
+
+package ExecutableSemanticsTest api;
+
+fn main() -> i32 {
+  return 0;
+}