Defer user error handlers raised from user-code opcodes

A user error handler raised mid-opcode can reenter the VM and free or
mutate state the opcode still holds a raw pointer into, a long-standing
source of use-after-free and memory-corruption bugs. Defer the handler
to the next vm_interrupt safepoint, after the opcode completes. The
interpreter and both JITs reach that safepoint through the existing
vm_interrupt mechanism. A diagnostic silenced by @ keeps its
error_reporting across the deferral; diagnostics raised from internal
functions still run synchronously, since the function may gate on
EG(exception) or throw right after emitting.

Function JIT flushes at the interpreter's safepoints: post-call with the
callee frame still on top, each jump-target block, and function entry,
spilling the live SSA values before it resumes. Exception handling
flushes any buffered diagnostic with the pending exception saved and
restored around the handler, so nothing is dropped when a later opcode
throws. Under the CALL VM the flush is deferred past a call being
assembled, so a throwing handler cannot unwind into a half-built frame
and fault in cleanup_unfinished_calls.

Fixes GH-20018
Fixes GH-16792
Fixes GH-17416
Fixes GH-18274
Fixes GH-20042
Fixes GH-21245
Fixes GH-22419

Author: iliaal

Zend/tests/ArrayAccess/bug41209.phpt

@@ -42,5 +42,6 @@ echo "Done\n";
 Fatal error: Uncaught ErrorException: Undefined variable $id in %s:%d
 Stack trace:
 #0 %s(%d): env::errorHandler(2, 'Undefined varia...', '%s', %d)
-#1 {main}
+#1 %s(%d): cache->offsetExists(NULL)
+#2 {main}
   thrown in %s on line %d

Zend/tests/bitwise_not_precision_exception.phpt

@@ -12,4 +12,5 @@ try {
 }
 ?>
 --EXPECT--
+int(-1)
 The float INF is not representable as an int, cast occurred

Zend/tests/bug63206.phpt

@@ -22,8 +22,10 @@ set_error_handler(function() {
 $triggerNotice1++;
 $triggerNotice2++;
 ?>
---EXPECT--
+--EXPECTF--
 Second handler
-Internal handler
+
+Warning: Undefined variable $triggerInternalNotice in %s on line %d
 Second handler
-Internal handler
+
+Warning: Undefined variable $triggerInternalNotice in %s on line %d

Zend/tests/bug70662.phpt

@@ -14,5 +14,5 @@ var_dump($a);
 --EXPECT--
 array(1) {
   ["b"]=>
-  int(2)
+  int(1)
 }

Zend/tests/bug70785.phpt

@@ -7,19 +7,32 @@ set_error_handler(function($no, $msg) {
     throw new Exception($msg);
 });
 
-try {
+function smart_branch() {
     if ($a === null) { // ZEND_VM_SMART_BRANCH
-        undefined_function('Null');
+        return 'branch';
     }
-} catch (Exception $e) {
+    return 'no branch';
 }
 
-try  {
+function next_opcode() {
     $c === 3; // ZEND_VM_NEXT_OPCODE
-    undefined_function();
+    return 'done';
+}
+
+try {
+    smart_branch();
 } catch (Exception $e) {
+    echo $e->getMessage(), PHP_EOL;
 }
+
+try {
+    next_opcode();
+} catch (Exception $e) {
+    echo $e->getMessage(), PHP_EOL;
+}
+echo "okey\n";
 ?>
-okey
 --EXPECT--
+Undefined variable $a
+Undefined variable $c
 okey

Zend/tests/bug72101.phpt

@@ -79,9 +79,10 @@ $foo->bar($a, $b, $c);
 Fatal error: Uncaught Error: Class "DoesNotExists" not found in %s:%d
 Stack trace:
 #0 %s(%d): {closure:%s:%d}(2, 'MethodCallbackB...', '%s', 8)
-#1 %sbug72101.php(%d): PHPUnit_Framework_MockObject_Stub_ReturnCallback->invoke(Object(PHPUnit_Framework_MockObject_Invocation_Static))
-#2 %sbug72101.php(%d): PHPUnit_Framework_MockObject_Matcher->invoked(Object(PHPUnit_Framework_MockObject_Invocation_Static))
-#3 %sbug72101.php(%d): PHPUnit_Framework_MockObject_InvocationMocker->invoke(Object(PHPUnit_Framework_MockObject_Invocation_Static))
-#4 %sbug72101.php(%d): Mock_MethodCallbackByReference_7b180d26->bar(0, 0, 0)
-#5 {main}
+#1 %sbug72101.php(%d): MethodCallbackByReference->callback(0, 0, 0)
+#2 %sbug72101.php(%d): PHPUnit_Framework_MockObject_Stub_ReturnCallback->invoke(Object(PHPUnit_Framework_MockObject_Invocation_Static))
+#3 %sbug72101.php(%d): PHPUnit_Framework_MockObject_Matcher->invoked(Object(PHPUnit_Framework_MockObject_Invocation_Static))
+#4 %sbug72101.php(%d): PHPUnit_Framework_MockObject_InvocationMocker->invoke(Object(PHPUnit_Framework_MockObject_Invocation_Static))
+#5 %sbug72101.php(%d): Mock_MethodCallbackByReference_7b180d26->bar(0, 0, 0)
+#6 {main}
   thrown in %sbug72101.php on line %d

Zend/tests/bug76534.phpt

@@ -10,8 +10,12 @@ $x = "foo";
 $y = &$x["2bar"];
 ?>
 --EXPECTF--
-Fatal error: Uncaught Exception: Illegal string offset "2bar" in %s:%d
+Fatal error: Uncaught Error: Cannot create references to/from string offsets in %s:%d
+Stack trace:
+#0 {main}
+
+Next Exception: Illegal string offset "2bar" in %s:%d
 Stack trace:
 #0 %s(%d): {closure:%s:%d}(2, 'Illegal string ...', '%s', 7)
 #1 {main}
-  thrown in %sbug76534.php on line %d
+  thrown in %s on line %d

Zend/tests/bug78598.phpt

@@ -25,7 +25,31 @@ var_dump($my_var);
 
 ?>
 --EXPECT--
-int(0)
-int(0)
-int(0)
-int(0)
+array(1) {
+  [0]=>
+  string(3) "xyz"
+}
+array(1) {
+  [0]=>
+  array(1) {
+    [0]=>
+    array(1) {
+      [0]=>
+      string(3) "xyz"
+    }
+  }
+}
+array(1) {
+  ["foo"]=>
+  string(3) "xyz"
+}
+array(1) {
+  ["foo"]=>
+  array(1) {
+    ["bar"]=>
+    array(1) {
+      ["baz"]=>
+      string(3) "xyz"
+    }
+  }
+}

Zend/tests/bug79784.phpt

@@ -15,6 +15,18 @@ var_dump($a);
 
 ?>
 --EXPECT--
-NULL
-NULL
-NULL
+array(1) {
+  [""]=>
+  string(1) "x"
+}
+array(1) {
+  [""]=>
+  string(1) "x"
+}
+array(1) {
+  [""]=>
+  array(1) {
+    [""]=>
+    string(1) "x"
+  }
+}

Zend/tests/bug79793.phpt

@@ -18,15 +18,15 @@ var_dump($ary);
 
 ?>
 --EXPECT--
-Undefined array key "foobar"
 array(1) {
   ["foobar"]=>
   int(1)
 }
-Undefined array key "foobarbaz"
+Undefined array key "foobar"
 array(2) {
   ["foobar"]=>
   int(1)
   ["foobarbaz"]=>
   int(1)
 }
+Undefined array key "foobarbaz"