From 580fcef90ab970ad37ea9f7059373f773b3e55d2 Mon Sep 17 00:00:00 2001
From: Jakub Pawlowski <jpawlowski@google.com>
Date: Fri, 03 Aug 2018 08:46:10 +0000
Subject: [PATCH] Fix data_types_definition.tmpl

This template can generate code that does not compile, if there are
multiple fields with different versions where at least one has version 0
and end up being laid out in a way that does not match the ordinal order

Sample Mojo file:
// Describes ARC package.
struct ArcPackageInfo {
  string package_name;
  int32 package_version;
  int64 last_backup_android_id;
  int64 last_backup_time;
  bool sync;  // true if package installation should be synced
  [MinVersion=11] bool system;  // true if package is system package.
  // true if package registers VPNService intent.
  [MinVersion=25] bool vpn_provider;
};

Sample badly generated code (no closing "}" for last if):

    @SuppressWarnings("unchecked")
    public static ArcPackageInfo decode(org.chromium.mojo.bindings.Decoder decoder0) {
        if (decoder0 == null) {
            return null;
        }
        decoder0.increaseStackDepth();
        ArcPackageInfo result;
        try {
            org.chromium.mojo.bindings.DataHeader mainDataHeader = decoder0.readAndValidateDataHeader(VERSION_ARRAY);
            final int elementsOrVersion = mainDataHeader.elementsOrVersion;
            result = new ArcPackageInfo(elementsOrVersion);
                {

                result.packageName = decoder0.readString(8, false);
                }
                {

                result.packageVersion = decoder0.readInt(16);
                }
                {

                result.sync = decoder0.readBoolean(20, 0);
                }
            if (elementsOrVersion >= 11) {
                {

                result.system = decoder0.readBoolean(20, 1);
                }
            }
            if (elementsOrVersion >= 25) {
                {

                result.vpnProvider = decoder0.readBoolean(20, 2);
                }
            }
            if (elementsOrVersion >= 0) {
                {

                result.lastBackupAndroidId = decoder0.readLong(24);
                }
                {

                result.lastBackupTime = decoder0.readLong(32);
                }
        } finally {
            decoder0.decreaseStackDepth();
        }
        return result;
    }

Change-Id: I4c1b573a71b20cc6a0828a2cceff6bbfbb4ac5bc
Reviewed-on: https://chromium-review.googlesource.com/1158702
Reviewed-by: Luis Hector Chavez <lhchavez@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Commit-Queue: Jakub x Jakub Pawlowski <jpawlowski@google.com>
Cr-Commit-Position: refs/heads/master@{#580480}
---

diff --git a/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl b/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
index 59c6fee..7af57bd 100644
--- a/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
+++ b/mojo/public/tools/bindings/generators/java_templates/data_types_definition.tmpl
@@ -175,6 +175,7 @@
             org.chromium.mojo.bindings.DataHeader mainDataHeader = decoder0.readAndValidateDataHeader(VERSION_ARRAY);
             final int elementsOrVersion = mainDataHeader.elementsOrVersion;
             result = new {{struct|name}}(elementsOrVersion);
+
 {%- set prev_ver = [0] %}
 {%- for byte in struct.bytes %}
 {%-   for packed_field in byte.packed_fields %}
@@ -183,7 +184,9 @@
             }
 {%-       endif %}
 {%-       set _ = prev_ver.append(packed_field.min_version) %}
+{%-       if prev_ver[-1] != 0 %}
             if (elementsOrVersion >= {{packed_field.min_version}}) {
+{%-       endif %}
 {%-     endif %}
                 {
                     {{decode('result.' ~ packed_field.field|name, packed_field.field.kind, 8+packed_field.offset, packed_field.bit)|indent(16)}}
@@ -193,6 +196,7 @@
 {%- if prev_ver[-1] != 0 %}
             }
 {%- endif %}
+
         } finally {
             decoder0.decreaseStackDepth();
         }