.vscode/tasks.json - Add 'cmake gen'

Allow the developer to pick either the GN or CMake build. Extract the lengthy string out to a new bash script in <dawn>/tools.

Windows CMake is TODO.

The Tint repo defaulted to using CMake, where as the Dawn repo defaulted to using GN. This gives us the best of both.

Bug: dawn:1339
Change-Id: Ibd5cf2a8f1c6d416b231d3267d68e006aee806be
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/86064
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@chromium.org>

.vscode/tasks.json

@@ -76,17 +76,17 @@
             "label": "gn gen",
             "type": "shell",
             "linux": {
-                "command": "sh",
+                "command": "./tools/setup-build",
                 "args": [
-                    "-c",
+                    "gn",
-                    "gn gen 'out/${input:buildType}' --args=is_debug=$(if [ '${input:buildType}' = 'Debug' ]; then echo 'true'; else echo 'false'; fi) && (rm -fr out/active || true) && ln -s ${input:buildType} out/active",
+                    "${input:buildType}",
                 ],
             },
             "osx": {
-                "command": "sh",
+                "command": "./tools/setup-build",
                 "args": [
-                    "-c",
+                    "gn",
-                    "gn gen 'out/${input:buildType}' --args=is_debug=$(if [ '${input:buildType}' = 'Debug' ]; then echo 'true'; else echo 'false'; fi) && (rm -fr out/active || true) && ln -s ${input:buildType} out/active",
+                    "${input:buildType}",
                 ],
             },
             "windows": {
@@ -105,6 +105,39 @@
             },
             "problemMatcher": [],
         },
+        {
+            "label": "cmake gen",
+            "type": "shell",
+            "linux": {
+                "command": "./tools/setup-build",
+                "args": [
+                    "cmake",
+                    "${input:buildType}",
+                ],
+            },
+            "osx": {
+                "command": "./tools/setup-build",
+                "args": [
+                    "cmake",
+                    "${input:buildType}",
+                ],
+            },
+            "windows": {
+                "command": "/C",
+                "args": [
+                    "echo TODO",
+                ],
+                "options": {
+                    "shell": {
+                        "executable": "cmd"
+                    },
+                }
+            },
+            "options": {
+                "cwd": "${workspaceRoot}"
+            },
+            "problemMatcher": [],
+        },
         // Rebases the current branch on to origin/main and then calls
         // `gclient sync`.
         {

tools/setup-build

@@ -0,0 +1,77 @@
+#!/usr/bin/env bash
+# Copyright 2022 The Tint Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+set -e # Fail on any error.
+
+SCRIPT_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd )"
+ROOT_DIR="$( cd "${SCRIPT_DIR}/.." >/dev/null 2>&1 && pwd )"
+BUILD_SYSTEM=$(echo "$1" | tr '[:upper:]' '[:lower:]') # lowercase
+BUILD_TYPE=$(echo "$2" | tr '[:upper:]' '[:lower:]') # lowercase
+BUILD_DIR="${BUILD_SYSTEM}-${BUILD_TYPE}"
+
+function show_usage() {
+  echo "setup-build [gn|cmake] [debug|release]"
+  echo
+  echo "creates a build directory in <dawn>/out using either GN or CMake, then"
+  echo "updates the '<dawn>/out/active' symlink to point to the build directory"
+  exit 1
+}
+
+function generate() {
+  CMD=$1
+  pushd "$ROOT_DIR" > /dev/null
+  ${CMD}
+  rm -fr "out/active" || true
+  ln -s "$BUILD_DIR" "out/active"
+  popd > /dev/null
+}
+
+case $BUILD_SYSTEM in
+  "gn")
+    case $BUILD_TYPE in
+      "debug")
+        generate "gn gen out/${BUILD_DIR} --args=is_debug=true"
+      ;;
+      "release")
+        generate "gn gen out/${BUILD_DIR}"
+      ;;
+      *)
+        echo "invalid build type '${BUILD_TYPE}'"
+        show_usage
+      ;;
+    esac
+  ;;
+  "cmake")
+    case $BUILD_TYPE in
+      "debug")
+        generate "cmake -S . -B out/$BUILD_DIR -GNinja -DCMAKE_BUILD_TYPE=Debug"
+      ;;
+      "release")
+        generate "cmake -S . -B out/$BUILD_DIR -GNinja -DCMAKE_BUILD_TYPE=RelWithDebInfo"
+      ;;
+      *)
+        echo "invalid build type '${BUILD_TYPE}'"
+        show_usage
+      ;;
+    esac
+  ;;
+  "--help" | "-help" | "-h")
+    show_usage
+  ;;
+  *)
+    echo "invalid build system '${BUILD_SYSTEM}'"
+    show_usage
+  ;;
+esac