I've tested this problem again with all current released versions, resulting thats only a problem with PHP 7 x64

ok with:

* php-5.6.33-Win32-VC11-x64
* php-5.6.33-Win32-VC11-x86
* php-7.0.27-Win32-VC14-x86
* php-7.1.13-Win32-VC14-x86
* php-7.2.1-Win32-VC15-x86

error with:

* php-7.0.27-Win32-VC14-x64
* php-7.1.13-Win32-VC14-x64
* php-7.2.1-Win32-VC15-x64

I found that RegRead works properly and GetStringValue doesn't.

$WSH        = new COM("WScript.Shell");
$value1     = $WSH->RegRead('HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion');

$StdRegProv = new COM("WinMgmts://localhost/root/default:StdRegProv");
$value2     = new VARIANT("", VT_BSTR); // 8
$retval     = $StdRegProv->GetStringValue(0x80000002, 'SOFTWARE\Microsoft\Windows NT\CurrentVersion','CurrentVersion' , $sValue);

With some other checks and PHP Source reading I found that the Value 0x80000002 makes the difference with the function php_com_variant_from_zval

with PHP x86 and PHP 5.6 x64  -> case IS_DOUBLE:

variant_get_type( new VARIANT(0x80000002 /* 2147483650 */));  // 5 = VT_R8

with PHP 7 x64 -> case IS_LONG:

variant_get_type( new VARIANT(0x80000002 /* 2147483650 */)); // 20 = VT_UI8 / VT_I8 ?

-> changed with https://github.com/php/php-src/commit/26e7e54e782d8ba80a7f964f0bfcc3a7920349c2

--

If you pin the types, every version is working properly

// uint32 = GetStringValue(uint32 hDefKey, string sSubKeyName, string sValueName, string &sValue) // Gets the string data value of a named value.

$sSubKeyName = new VARIANT('SOFTWARE\Microsoft\Windows NT\CurrentVersion', VT_BSTR); // 8
$sValueName  = new VARIANT('CurrentVersion', VT_BSTR); // 8
$sValue      = new VARIANT("", VT_BSTR); // 8
$hDefKey     = new VARIANT(0x80000002 /* 2147483650 */, VT_R8 ); // 5

$StdRegProv = new COM("WinMgmts://localhost/root/default:StdRegProv");
$retval = $StdRegProv->GetStringValue($hDefKey, $sSubKeyName,$sValueName , $sValue);
// $sValue = "6.1" on Win7

---

The posted test scripts works correctly on PHP 7.x x64 if you fix the type to VT_R8

define('HKEY_LOCAL_MACHINE', 0x80000002);
$StdRegProv = new COM("WinMgmts:{impersonationLevel=impersonate}//localhost/root/default:StdRegProv");
$valueNames = new Variant(array(), VT_ARRAY);
$valueTypes = new Variant(array(), VT_ARRAY);

$hDefKey = new Variant(HKEY_LOCAL_MACHINE, VT_R8); // patch
try {
    $StdRegProv->EnumValues($hDefKey, "SOFTWARE\Microsoft\Windows NT\CurrentVersion", $valueNames, $valueTypes);
    foreach($valueNames as $name) {
        echo "[" . __LINE__ . "] " . "name: $name \n";
    }
    foreach($valueTypes as $type) {
        echo "[" . __LINE__ . "] " . "type: $type \n";
    }
} catch (Exception $e) {
    echo "[" . __LINE__ . "] " . "Exception $e\n";
    echo "[" . __LINE__ . "] " . "var_dump:\n"; var_dump($e);
    echo "[" . __LINE__ . "] " . "print_r:\n"; print_r($e);
}

----

* I don't understand why i can't use VT_UI4 for hDefKey but thats an API and no PHP problem, isn't?

* VT_UI8 and VT_I8 are not documented http://php.net/manual/en/com.constants.php

* was this change VT_R8 to VT_I8 intended or a side effect ?

Thanks for the report. This is a dup of bug #73605.

You need to use the exact datatype as API requires

define('HKEY_LOCAL_MACHINE', new VARIANT(0x80000002, VT_UI8));

See also https://msdn.microsoft.com/de-de/library/aa390388(v=vs.85).aspx

Thanks.

Typo there, 

define('HKEY_LOCAL_MACHINE', new VARIANT(0x80000002, VT_UI4));

Thanks.