feat(build): support stub files in incremental compilation

- Add getDeclarationInputFiles method to include stub files in header generation
- Modify incremental compilation to process stub files alongside regular PHP files
- Update build state tracking to handle stub files differently (no translation units)
- Add test coverage for stub declaration generation and dependency invalidation
- Implement MSVC /bigobj flag for large object format support in generated commands
- Generate wrapper callbacks for stub functions and methods bridging to native implementations
- Update source pipeline to handle native/import stub metadata in module entry
- Modify declaration header generation to include stub callback registrations
- Add comprehensive test suite for stub functionality

.github/smoke/linux-arm64/.gitignore

@@ -0,0 +1,2 @@
+/build
+/linux_arm64_smoke

phpunit/src/Backend/BackendTest.php

@@ -117,6 +117,17 @@ class BackendTest extends TestCase
         $this->assertStringNotContainsString('/std:', $cmd);
     }
 
+    public function testMsvcLargeObjectFormatAppliesToGeneratedAndNativeCommands(): void
+    {
+        $compiler = new Msvc(new Windows());
+        foreach ([false, true] as $debug) {
+            $options = ['debug' => $debug];
+            $this->assertStringContainsString('/bigobj', $compiler->buildCompileCommand('generated.cc', 'generated.obj', $options));
+            $this->assertStringContainsString('/bigobj', $compiler->buildNativeCompileCommand('native.c', 'native.obj', $options, 'c'));
+        }
+        $this->assertStringNotContainsString('/bigobj', $compiler->buildLinkOptions());
+    }
+
     public function testMsvcDebugPdbOptionsApplyToCppAndCCommands(): void
     {
         $compiler = new Msvc(new Windows());

phpunit/src/Build/IncrementalDeclarationTest.php

@@ -316,6 +316,112 @@ PHP);
         self::assertDirectoryDoesNotExist($incrementalDirectory);
     }
 
+    private function prepareNativeStub(): void
+    {
+        $stub = $this->directory . '/provider.stub.php';
+        rename($this->provider, $stub);
+        $this->provider = $stub;
+        file_put_contents($stub, '<?php namespace Incremental; function answer(int $value = 42): int {}');
+        file_put_contents($this->consumer, '<?php function main(): int { return \\Incremental\\answer(); }');
+    }
+
+    public function testStubDeclarationsAreGeneratedWithoutConvertingStubBodies(): void
+    {
+        $this->prepareNativeStub();
+        $first = $this->convertProject();
+        $header = $first->getDeclarationHeaderFile($this->provider);
+        self::assertFileExists($header);
+        self::assertStringContainsString('php_incremental__answer(', file_get_contents($header));
+        self::assertStringContainsString('#include <' . basename($header) . '>',
+            file_get_contents($first->getDeclarationHeaderFile($this->consumer)));
+        self::assertFileDoesNotExist($this->invoke($first, 'getCppFile', $this->provider));
+        self::assertFileExists($first->getArgInfoHeaderFile($this->provider));
+        $extension = $this->buildDirectory . '/extension-incremental.cc';
+        $extensionCode = file_get_contents($extension);
+        self::assertStringContainsString('ZEND_FUNCTION(incremental_answer)', $extensionCode);
+        self::assertStringContainsString('#include <' . basename($first->getArgInfoHeaderFile($this->provider)) . '>', $extensionCode);
+        $state = json_decode(file_get_contents($this->buildDirectory . '/cache/incremental/incremental/build-state.json'), true);
+        self::assertFalse($state['files'][$this->provider]['emitsTranslationUnit']);
+        self::assertContains($this->provider, $state['files'][$this->consumer]['dependencies']);
+        $second = $this->convertProject();
+        self::assertFalse($this->invoke($second, 'shouldRegeneratePhpFile', $this->provider));
+        self::assertFalse($this->invoke($second, 'shouldRegeneratePhpFile', $this->consumer));
+        self::assertSame($extensionCode, file_get_contents($extension));
+    }
+
+    public function testStubChangePreservingMtimeInvalidatesTheConsumer(): void
+    {
+        $this->prepareNativeStub();
+        $this->convertProject();
+        $extension = $this->buildDirectory . '/extension-incremental.cc';
+        $oldCode = file_get_contents($extension);
+        $mtime = filemtime($this->provider);
+        file_put_contents($this->provider, str_replace('42', '43', file_get_contents($this->provider)));
+        touch($this->provider, $mtime);
+        clearstatcache();
+        $second = $this->convertProject();
+        self::assertTrue($this->invoke($second, 'shouldRegeneratePhpFile', $this->provider));
+        self::assertTrue($this->invoke($second, 'shouldRegeneratePhpFile', $this->consumer));
+        self::assertNotSame($oldCode, file_get_contents($extension));
+        self::assertStringContainsString('43', file_get_contents($extension));
+    }
+
+    public function testMissingStubHeaderIsRegeneratedAndInvalidatesConsumers(): void
+    {
+        $this->prepareNativeStub();
+        $first = $this->convertProject();
+        unlink($first->getDeclarationHeaderFile($this->provider));
+        $second = $this->convertProject();
+        self::assertFileExists($second->getDeclarationHeaderFile($this->provider));
+        self::assertTrue($this->invoke($second, 'shouldRegeneratePhpFile', $this->consumer));
+    }
+
+    public function testMissingStubArginfoIsRegeneratedAndInvalidatesConsumers(): void
+    {
+        $this->prepareNativeStub();
+        $first = $this->convertProject();
+        unlink($first->getArgInfoHeaderFile($this->provider));
+        $second = $this->convertProject();
+        self::assertFileExists($second->getArgInfoHeaderFile($this->provider));
+        self::assertTrue($this->invoke($second, 'shouldRegeneratePhpFile', $this->consumer));
+    }
+
+    public function testImportedClassMetadataAndCallbacksStayInTheExtension(): void
+    {
+        $this->prepareNativeStub();
+        file_put_contents($this->provider, <<<'PHP'
+<?php
+/** @import-library */
+namespace Incremental;
+function answer(int $value = 42): int {}
+final class Counter
+{
+    public int $value = 0;
+    public function add(int $delta): int {}
+}
+PHP);
+        file_put_contents($this->consumer, <<<'PHP'
+<?php
+function main(): int
+{
+    $counter = new \Incremental\Counter();
+    return $counter->add(1) + \Incremental\answer();
+}
+PHP);
+        $first = $this->convertProject();
+        $arginfo = $first->getArgInfoHeaderFile($this->provider);
+        $extension = $this->buildDirectory . '/extension-incremental.cc';
+        $extensionCode = file_get_contents($extension);
+        self::assertStringContainsString('php_register_class_Incremental_Counter', file_get_contents($arginfo));
+        self::assertStringContainsString('ZEND_METHOD(Incremental_Counter, add)', $extensionCode);
+        self::assertStringContainsString('php_incremental__counter__add(this_, arg_delta)', $extensionCode);
+        self::assertStringContainsString('#include <' . basename($arginfo) . '>', $extensionCode);
+        self::assertStringNotContainsString(basename($arginfo), file_get_contents($this->invoke($first, 'getCppFile', $this->consumer)));
+        self::assertFileDoesNotExist($this->invoke($first, 'getCppFile', $this->provider));
+        $this->convertProject();
+        self::assertSame($extensionCode, file_get_contents($extension));
+    }
+
     private function convertProject(): CompilerTest
     {
         global $translator;

src/Backend/Msvc.php

@@ -36,7 +36,8 @@ class Msvc extends CompilerBackend
 
     private function buildCommonCompileFlags(array $config, bool $includeCppOptions = true): string
     {
-        $cmd = '';
+        // Generated code/templates can exceed ordinary COFF section limits.
+        $cmd = ' /bigobj';
 
         $cmd .= ' /utf-8 /DZEND_WIN32 /DPHP_WIN32 /DZEND_DEBUG=0 /DENABLE_INTSAFE_SIGNED_FUNCTIONS';
 

src/Build/IncrementalCompilationTrait.php

@@ -20,6 +20,26 @@ trait IncrementalCompilationTrait
     private string $incrementalGeneratorFingerprint = '';
     private bool $incrementalPlanInitialized = false;
 
+    /**
+     * Stubs provide declarations without emitting a body translation unit.
+     * Include them in header generation and dependency invalidation as well.
+     * @param list<string> $files
+     * @return list<string>
+     */
+    private function getDeclarationInputFiles(array $files): array
+    {
+        $inputs = [];
+        foreach ($files as $file) {
+            $inputs[realpath($file) ?: $file] = true;
+        }
+        foreach ($this->preparedFileAsts as $file => $_ast) {
+            if ($this->isStubFile($file)) {
+                $inputs[$file] = true;
+            }
+        }
+        return array_keys($inputs);
+    }
+
     /** @param list<string> $files */
     protected function initializeIncrementalCompilation(array $files): void
     {
@@ -29,7 +49,7 @@ trait IncrementalCompilationTrait
         $this->incrementalDirtyFiles = [];
 
         $phpFiles = [];
-        foreach ($files as $file) {
+        foreach ($this->getDeclarationInputFiles($files) as $file) {
             if (!FileScanner::isPhpFile($file)) {
                 continue;
             }
@@ -112,7 +132,7 @@ trait IncrementalCompilationTrait
         if (!$this->incrementalPlanInitialized) {
             return;
         }
-        foreach ($files as $file) {
+        foreach ($this->getDeclarationInputFiles($files) as $file) {
             if (!FileScanner::isPhpFile($file)) {
                 continue;
             }
@@ -198,7 +218,7 @@ trait IncrementalCompilationTrait
         }
         $this->rebuildIncrementalGlobalState();
         $phpFiles = [];
-        foreach ($files as $file) {
+        foreach ($this->getDeclarationInputFiles($files) as $file) {
             if (!FileScanner::isPhpFile($file)) {
                 continue;
             }
@@ -218,7 +238,7 @@ trait IncrementalCompilationTrait
         }
         $this->rebuildIncrementalGlobalState();
         $stateFiles = [];
-        foreach ($files as $file) {
+        foreach ($this->getDeclarationInputFiles($files) as $file) {
             if (!FileScanner::isPhpFile($file)) {
                 continue;
             }
@@ -248,7 +268,7 @@ trait IncrementalCompilationTrait
                 'symbolsDeclared' => $declared,
                 'symbolsUsed' => $used,
                 'emitsTranslationUnit' => $this->incrementalTranslationUnits[$path]
-                    ?? (bool) ($previous['emitsTranslationUnit'] ?? false),
+                    ?? (!$this->isStubFile($path) && (bool) ($previous['emitsTranslationUnit'] ?? false)),
                 'header' => $this->getDeclarationHeaderFile($path),
                 'cpp' => $this->getCppFile($path),
                 'splitTranslationUnits' => $this->getSplitTranslationUnits($path),

src/Build/SourcePipelineTrait.php

@@ -368,7 +368,7 @@ trait SourcePipelineTrait
             // All declarations are now known. Lower declaration constant
             // expressions before translating any function body so cache IDs
             // are assigned exclusively in the convert phase.
-            $this->finalizeDeclarationExpressions($files);
+            $this->finalizeDeclarationExpressions($this->getDeclarationInputFiles($files));
             // Whole-program extension generation must not depend on conversion
             // side effects from dirty files. Clean incremental files are not
             // converted, but their non-empty property defaults still require a
@@ -377,6 +377,14 @@ trait SourcePipelineTrait
             $this->initializeDeclarationHeaderFiles($files);
             $this->restoreCleanIncrementalMetadata($files);
 
+            // Native/import stubs are declaration inputs, not ordinary PHP
+            // bodies. Their Zend metadata still belongs to the module entry.
+            foreach ($this->getDeclarationInputFiles($files) as $file) {
+                if ($this->isStubFile($file) && $this->shouldRegeneratePhpFile($file)) {
+                    $this->genStubFile($file);
+                }
+            }
+
             $sourceFiles = [];
             $validSourceCount = 0;
             // Generate the C++ files

src/Translator.php

@@ -1193,6 +1193,10 @@ class Translator extends Preprocessor
         sort($this->registerSymbols, SORT_STRING);
         sort($this->releaseAstConstantFns, SORT_STRING);
         $this->localHeaders = $this->argInfoHeaderFiles;
+        // Stubs have native implementations, but still need local Zend
+        // callbacks. Generate these before sizing caches/rendering literals:
+        // parameter validation may allocate additional stable cache IDs.
+        $stubWrapperCode = $this->genStubWrappers();
         // genExtension() is also a public code-generation entry used directly
         // by tooling and tests, outside SourcePipelineTrait::convert(). Keep the
         // whole-program property-default invariant local to the consumer too.
@@ -1395,6 +1399,9 @@ CODE;
 
         $code .= '}  // namespace ' . $projectNamespace . PHP_EOL . PHP_EOL;
 
+        $code .= "// native/import stub callbacks \n";
+        $code .= $stubWrapperCode;
+
         $code .= "// default argument values \n";
         $code .= $this->genDefaultArgumentHelperDefinitions();
 
@@ -2770,7 +2777,7 @@ CODE;
     private function initializeDeclarationHeaderFiles(array $files): void
     {
         $this->declarationHeaderFiles = [];
-        foreach ($files as $file) {
+        foreach ($this->getDeclarationInputFiles($files) as $file) {
             if (FileScanner::isPhpFile($file)) {
                 $this->declarationHeaderFiles[$file] = $this->getDeclarationHeaderFile($file, true);
             }
@@ -2831,17 +2838,14 @@ CODE;
         $this->writeFile($runtimeHeader, '#pragma once' . PHP_EOL . PHP_EOL
             . $this->renderDataDeclarations(null, true)
             . $this->genNativeObjectForwardDeclarations());
-        foreach ($files as $file) {
-            if (!isset($this->declarationHeaderFiles[$file])) {
-                continue;
-            }
+        foreach ($this->declarationHeaderFiles as $file => $header) {
             if (!$this->shouldRegeneratePhpFile($file)) {
                 continue;
             }
             $code = $this->renderFunctionDeclarations($file);
             $code .= $this->renderDataDeclarations($file);
             $this->writeFile(
-                $this->getIncludeDir() . '/' . $this->declarationHeaderFiles[$file],
+                $this->getIncludeDir() . '/' . $header,
                 $code,
                 $this->shouldRegeneratePhpFile($file),
             );
@@ -3060,6 +3064,13 @@ CODE;
             ];
         } else {
             $declarationHeaders = [$this->getRuntimeDeclarationHeaderName()];
+            // The callbacks emitted here bridge stub declarations to native
+            // C++ implementations. Arginfo remains included only by this TU.
+            foreach ($this->declarationHeaderFiles as $source => $header) {
+                if ($this->isStubFile($source)) {
+                    $declarationHeaders[] = $header;
+                }
+            }
             // Generated arginfo registration helpers call compile-time
             // attribute factories directly to materialize lazy values such as
             // enum cases. Include only the declaration owners of those helper
@@ -8410,6 +8421,29 @@ CODE;
         return $cppCode;
     }
 
+    private function genStubWrappers(): string
+    {
+        $code = '';
+        foreach ($this->symbols->classes() as $classDef) {
+            if (!$this->isStubFile($classDef->sourceFile) || $classDef->nativeObject || $classDef->trait !== null) {
+                continue;
+            }
+            foreach ($classDef->methods as $methodDef) {
+                if (!$methodDef->functionDef->abstractMethod
+                    && !$this->functionUsesNativeObject($methodDef->functionDef)) {
+                    $code .= $this->genMethodWrapper($classDef, $methodDef);
+                }
+            }
+        }
+        foreach ($this->symbols->functions() as $functionDef) {
+            if ($functionDef->stub && !$functionDef->method && !$functionDef->attributeFactory
+                && !$this->functionUsesNativeObject($functionDef)) {
+                $code .= $this->genFunctionWrapper($functionDef);
+            }
+        }
+        return $code;
+    }
+
     /** Return the generated C++ symbol for a hidden runtime-attribute factory. */
     public function getRuntimeAttributeFactoryNativeName(string $fullName): string
     {