[C++] Ninja: Detect and drop mkdir -p $(dir $@)

Ninja automatically creates the necessary output directories.

This also fixes the logic to remove the empty '(true) &&' that was added
for echo -> description detection.

2 files changed, 71 insertions, 5 deletions

diff --git a/ninja.cc b/ninja.cc
index f14610f..13d5e0c 100644
--- a/ninja.cc
+++ b/ninja.cc
@@ -284,6 +284,22 @@ class NinjaGenerator {
                        cmd_buf->size() - orig_size);
   }
 
+  bool IsOutputMkdir(const char *name, StringPiece cmd) {
+    if (!HasPrefix(cmd, "mkdir -p ")) {
+      return false;
+    }
+    cmd = cmd.substr(9, cmd.size());
+    if (cmd.get(cmd.size() - 1) == '/') {
+      cmd = cmd.substr(0, cmd.size() - 1);
+    }
+
+    StringPiece dir = Dirname(name);
+    if (cmd == dir) {
+      return true;
+    }
+    return false;
+  }
+
   bool GetDescriptionFromCommand(StringPiece cmd, string *out) {
     if (!HasPrefix(cmd, "echo ")) {
       return false;
@@ -333,7 +349,8 @@ class NinjaGenerator {
     return true;
   }
 
-  bool GenShellScript(const vector<Command*>& commands,
+  bool GenShellScript(const char *name,
+                      const vector<Command*>& commands,
                       string* cmd_buf,
                       string* description) {
     // TODO: This is a dirty hack to set local_pool even without
@@ -347,7 +364,10 @@ class NinjaGenerator {
     bool got_descritpion = false;
     bool use_gomacc = false;
     bool should_ignore_error = false;
+    auto command_count = commands.size();
     for (const Command* c : commands) {
+      size_t cmd_begin = cmd_buf->size();
+
       if (!cmd_buf->empty()) {
         if (should_ignore_error) {
           *cmd_buf += " ; ";
@@ -361,7 +381,7 @@ class NinjaGenerator {
       while (isspace(*in))
         in++;
 
-      bool needs_subshell = commands.size() > 1;
+      bool needs_subshell = command_count > 1;
       if (*in == '(') {
         needs_subshell = false;
       }
@@ -374,11 +394,15 @@ class NinjaGenerator {
       if (g_flags.detect_android_echo && !got_descritpion && !c->echo &&
           GetDescriptionFromCommand(translated, description)) {
         got_descritpion = true;
-        cmd_buf->resize(cmd_start);
+        translated.clear();
+      } else if (IsOutputMkdir(name, translated) && !c->echo &&
+                 cmd_begin == 0) {
         translated.clear();
       }
       if (translated.empty()) {
-        *cmd_buf += "true";
+        cmd_buf->resize(cmd_begin);
+        command_count -= 1;
+        continue;
       } else if (g_flags.goma_dir) {
         size_t pos = GetGomaccPosForAndroidCompileCommand(translated);
         if (pos != string::npos) {
@@ -447,7 +471,7 @@ class NinjaGenerator {
 
       string description = "build $out";
       string cmd_buf;
-      use_local_pool |= GenShellScript(commands, &cmd_buf, &description);
+      use_local_pool |= GenShellScript(node->output.c_str(), commands, &cmd_buf, &description);
       fprintf(fp_, " description = %s\n", description.c_str());
       EmitDepfile(node, &cmd_buf);
 
diff --git a/testcase/ninja_mkdir.sh b/testcase/ninja_mkdir.sh
new file mode 100644
index 0000000..e54298d
--- /dev/null
+++ b/testcase/ninja_mkdir.sh
@@ -0,0 +1,42 @@
+#!/bin/sh
+#
+# Copyright 2016 Google Inc. All rights reserved
+#
+# 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
+
+log=/tmp/log
+mk="$@"
+
+cat <<EOF > Makefile
+test: a/b
+
+a/b:
+	@mkdir -p \$(dir \$@)
+	touch \$@
+EOF
+
+${mk} 2> ${log}
+if [ -e ninja.sh ]; then
+  ./ninja.sh
+fi
+if [[ ! -d a ]]; then
+  echo "Created 'a'"
+fi
+if [ -e ninja.sh ]; then
+  if grep -q "mkdir -p" build.ninja; then
+    echo "Should not include 'mkdir -p' in build.ninja"
+    echo "Ninja will automatically create this directory"
+  fi
+fi