From 88107fa030786946b7f9a4d2db695bddf987a5a9 Mon Sep 17 00:00:00 2001
From: Kevin Viratyosin <viratyosin@fb.com>
Date: Wed, 8 May 2019 15:00:04 -0700
Subject: [PATCH] Avoid `Lval on missing array element` logs from
 `IniSettingMap::set`

Summary:
The following command was resulting in stackless notices `Hack Array Compat: Lval on missing array element`:
```
/usr/local/hphpi/bin/hhvm -vEval.HackArrCompatNotices=1 -vEval.HackArrCompatCheckFalseyPromote=1 -m debug
```
I used `gdb` to trace this to two `lvalAt` calls via `IniSettingMap::set`.

I'm not sure if initializing the value at the missing key to null (`empty_array()`) is the best thing to but, it looks like the merging will just overwrite it.

Reviewed By: mofarrell

Differential Revision: D15202922

fbshipit-source-id: 354cd3e36f53a05aee33dc49208897413ac0dc73
---
 hphp/runtime/base/ini-setting.cpp                      | 12 ++++++++++--
 hphp/test/slow/debugger/no-lval-on-missing.php         |  1 +
 hphp/test/slow/debugger/no-lval-on-missing.php.expectf |  2 ++
 hphp/test/slow/debugger/no-lval-on-missing.php.opts    |  1 +
 4 files changed, 14 insertions(+), 2 deletions(-)
 create mode 100644 hphp/test/slow/debugger/no-lval-on-missing.php
 create mode 100644 hphp/test/slow/debugger/no-lval-on-missing.php.expectf
 create mode 100644 hphp/test/slow/debugger/no-lval-on-missing.php.opts

diff --git a/hphp/runtime/base/ini-setting.cpp b/hphp/runtime/base/ini-setting.cpp
index 750e1d45953..9e40c356b1c 100644
--- a/hphp/runtime/base/ini-setting.cpp
+++ b/hphp/runtime/base/ini-setting.cpp
@@ -554,7 +554,11 @@ void mergeSettings(tv_lval curval, TypedValue v) {
   if (isArrayLikeType(cell.m_type) &&
       isArrayLikeType(cur_inner.type())) {
     for (auto i = ArrayIter(cell.m_data.parr); !i.end(); i.next()) {
-      mergeSettings(asArrRef(cur_inner).lvalAt(i.first()), i.secondVal());
+      auto& cur_inner_ref = asArrRef(cur_inner);
+      if (!cur_inner_ref.exists(i.first())) {
+        cur_inner_ref.set(i.first(), empty_array());
+      }
+      mergeSettings(cur_inner_ref.lvalAt(i.first()), i.secondVal());
     }
   } else {
     tvSet(tvToInitCell(v), curval);
@@ -564,7 +568,11 @@ void mergeSettings(tv_lval curval, TypedValue v) {
 
 void IniSettingMap::set(const String& key, const Variant& v) {
   assertx(this->isArray());
-  auto const curval = m_map.toArrRef().lvalAt(key);
+  auto& mapref = m_map.toArrRef();
+  if (!mapref.exists(key)) {
+    mapref.set(key, empty_array());
+  }
+  auto const curval = mapref.lvalAt(key);
   mergeSettings(curval, *v.asTypedValue());
 }
 
diff --git a/hphp/test/slow/debugger/no-lval-on-missing.php b/hphp/test/slow/debugger/no-lval-on-missing.php
new file mode 100644
index 00000000000..d2b3750ee00
--- /dev/null
+++ b/hphp/test/slow/debugger/no-lval-on-missing.php
@@ -0,0 +1 @@
+<?hh
diff --git a/hphp/test/slow/debugger/no-lval-on-missing.php.expectf b/hphp/test/slow/debugger/no-lval-on-missing.php.expectf
new file mode 100644
index 00000000000..691bda949bb
--- /dev/null
+++ b/hphp/test/slow/debugger/no-lval-on-missing.php.expectf
@@ -0,0 +1,2 @@
+Program %s loaded%s
+quit
diff --git a/hphp/test/slow/debugger/no-lval-on-missing.php.opts b/hphp/test/slow/debugger/no-lval-on-missing.php.opts
new file mode 100644
index 00000000000..c895f8f95e2
--- /dev/null
+++ b/hphp/test/slow/debugger/no-lval-on-missing.php.opts
@@ -0,0 +1 @@
+-vEval.HackArrCompatNotices=1 -vEval.HackArrCompatCheckFalseyPromote=1
-- 
2.11.4.GIT