THRIFT-5759: Remove mbstring.func_overload workaround from PHP library

Client: php

The mbstring.func_overload PHP ini setting was deprecated in PHP 7.2
and removed in PHP 8.0. Since THRIFT-5956 raised the project's minimum
PHP version to 8.1, the TStringFunc abstraction guarding against this
setting has been functionally unreachable in every supported runtime
(ini_get('mbstring.func_overload') always returns false). This removes
the dead code; native strlen()/substr() already return byte counts on
PHP 8.1+, which is what Thrift's binary protocols need.

- Delete Thrift\Factory\TStringFuncFactory, Thrift\StringFunc\{Core,
  Mbstring, TStringFunc}, and legacy lib/php/src/TStringUtils.php.
- Replace 30+ TStringFuncFactory::create()->strlen/substr call sites
  in lib/Transport/* and lib/Protocol/* with native strlen()/substr().
- Initialize TFramedTransport::$rBuf_ and $wBuf_ to '' (instead of the
  default null) and reset $rBuf_ to '' after a frame is consumed, so
  the new direct strlen()/substr() calls never receive null and never
  trigger the PHP 8.1 "passing null to parameter of type string is
  deprecated" warning that the deleted Core wrapper used to mask via
  (string)$str casts.
- Drop the corresponding unit tests (TStringFuncFactoryTest, CoreTest,
  MbStringTest) and remove the obsolete mbstring.func_overload=0 ini
  override from src/ext/thrift_protocol/run-tests.php.
- Add a regression test (StringByteCountTest) that pins the byte-count
  contract: TBinaryProtocol/TCompactProtocol round-trip non-ASCII UTF-8
  payloads (Cyrillic, Arabic, CJK, Malayalam, emoji, etc.) intact, and
  the on-the-wire i32 length prefix matches the byte length, not the
  character count. The test also covers TFramedTransport on top of
  TMemoryBuffer to exercise the rBuf_ exhaustion path.
- No mb_* function calls remain anywhere in lib/php, test/php, the
  tutorial, or the C extension, so drop mbstring from build.yml,
  sca.yml, and the focal/jammy/noble Dockerfiles.
- Update lib/php/Makefile.am to drop the phpstringfuncdir block and
  the src/TStringUtils.php distribution entry; src/Thrift.php no
  longer includes the deleted TStringUtils.php.

The Thrift code generator does not emit any TStringFunc* references,
so generated user code is unaffected.

Generated-by: Claude Opus 4.7 <noreply@anthropic.com>

Author: sveneld

.github/workflows/build.yml

@@ -168,7 +168,7 @@ jobs:
         uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # master
         with:
           php-version: ${{ matrix.php-version }}
-          extensions: mbstring, intl, xml, curl
+          extensions: intl, xml, curl
           ini-values: "error_reporting=E_ALL"
 
       - name: Install Dependencies
@@ -956,7 +956,7 @@ jobs:
         uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # master
         with:
           php-version: "8.3"
-          extensions: mbstring, intl, xml, curl, sockets
+          extensions: intl, xml, curl, sockets
           ini-values: "error_reporting=E_ALL"
 
       - name: Install PHP dependencies

.github/workflows/sca.yml

@@ -270,7 +270,7 @@ jobs:
         with:
           # Lowest supported PHP version
           php-version: "8.1"
-          extensions: mbstring, xml, curl, pcntl
+          extensions: xml, curl, pcntl
 
       - name: Configure
         run: |

build/docker/ubuntu-focal/Dockerfile

@@ -244,7 +244,6 @@ RUN apt-get install -y --no-install-recommends \
       php8.1 \
       php8.1-cli \
       php8.1-dev \
-      php8.1-mbstring \
       php8.1-xml \
       php8.1-curl \
       php8.1-xdebug \

build/docker/ubuntu-jammy/Dockerfile

@@ -233,7 +233,6 @@ RUN apt-get install -y --no-install-recommends \
   php8.1 \
   php8.1-cli \
   php8.1-dev \
-  php8.1-mbstring \
   php8.1-xml \
   php8.1-curl \
   php8.1-xdebug \

build/docker/ubuntu-noble/Dockerfile

@@ -232,7 +232,6 @@ RUN apt-get install -y --no-install-recommends \
   php8.3 \
   php8.3-cli \
   php8.3-dev \
-  php8.3-mbstring \
   php8.3-xml \
   php8.3-curl \
   php8.3-xdebug \

lib/php/Makefile.am

@@ -63,7 +63,6 @@ phpfactory_DATA = \
 	lib/Factory/TCompactProtocolFactory.php \
 	lib/Factory/TJSONProtocolFactory.php \
 	lib/Factory/TProtocolFactory.php \
-	lib/Factory/TStringFuncFactory.php \
 	lib/Factory/TTransportFactoryInterface.php \
 	lib/Factory/TTransportFactory.php \
 	lib/Factory/TFramedTransportFactory.php
@@ -106,12 +105,6 @@ phpserver_DATA = \
 	lib/Server/TServerTransport.php \
 	lib/Server/TSimpleServer.php
 
-phpstringfuncdir = $(phpdir)/StringFunc
-phpstringfunc_DATA = \
-	lib/StringFunc/Mbstring.php \
-	lib/StringFunc/Core.php \
-	lib/StringFunc/TStringFunc.php
-
 phptransportdir = $(phpdir)/Transport
 phptransport_DATA = \
 	lib/Transport/TBufferedTransport.php \
@@ -147,7 +140,6 @@ EXTRA_DIST = \
 	src/ext/thrift_protocol/php_thrift_protocol.stub.php \
 	src/ext/thrift_protocol/php_thrift_protocol_arginfo.h \
 	src/Thrift.php \
-	src/TStringUtils.php \
 	coding_standards.md \
 	thrift_protocol.ini \
 	phpunit.xml \

lib/php/lib/Factory/TStringFuncFactory.php

@@ -24,7 +24,6 @@
 
 use Thrift\Type\TType;
 use Thrift\Exception\TProtocolException;
-use Thrift\Factory\TStringFuncFactory;
 
 /**
  * Binary implementation of the Thrift protocol.
@@ -211,7 +210,7 @@ public function writeDouble($value)
 
     public function writeString($value)
     {
-        $len = TStringFuncFactory::create()->strlen($value);
+        $len = strlen($value);
         $result = $this->writeI32($len);
         if ($len) {
             $this->trans_->write($value, $len);

lib/php/lib/Protocol/TBinaryProtocol.php

@@ -24,7 +24,6 @@
 
 use Thrift\Type\TType;
 use Thrift\Exception\TProtocolException;
-use Thrift\Factory\TStringFuncFactory;
 
 /**
  * Compact implementation of the Thrift protocol.
@@ -136,7 +135,7 @@ public function getVarint($data)
     public function writeVarint($data)
     {
         $out = $this->getVarint($data);
-        $result = TStringFuncFactory::create()->strlen($out);
+        $result = strlen($out);
         $this->trans_->write($out, $result);
 
         return $result;
@@ -364,7 +363,7 @@ public function writeDouble($value)
 
     public function writeString($value)
     {
-        $len = TStringFuncFactory::create()->strlen($value);
+        $len = strlen($value);
         $result = $this->writeVarint($len);
         if ($len) {
             $this->trans_->write($value, $len);
@@ -761,7 +760,7 @@ public function writeI64($value)
                 }
             }
 
-            $ret = TStringFuncFactory::create()->strlen($out);
+            $ret = strlen($out);
             $this->trans_->write($out, $ret);
 
             return $ret;