Fix nested @partial-block error with runtime partials

Also fixed failover rendering when a template contains a conditional call to a missing partial prior to calling it with block syntax and failover content.

Author: theodorejb

src/Compiler.php

@@ -78,10 +78,9 @@ public function compile(Program $program, Context $context): string
      */
     public function composePHPRender(string $code): string
     {
-        $runtime = Runtime::class;
         $partials = implode(",\n", $this->context->partialCode);
         $closure = self::templateClosure($code, $partials, "\n \$in = &\$cx->data['root'];");
-        return "use {$runtime} as LR;\nreturn $closure;";
+        return "use " . Runtime::class . " as LR;\nreturn $closure;";
     }
 
     /**
@@ -274,7 +273,7 @@ private function compileProgramWithBlockParams(Program $program): string
         if ($bp) {
             array_shift($this->blockParamValues);
         }
-        return self::blockClosure($body, (bool) $program->blockParams, $this->lastCompileProgramHadDirectBpRef);
+        return self::blockClosure($body, (bool) $bp, $this->lastCompileProgramHadDirectBpRef);
     }
 
     private function compileBlockHelper(BlockStatement $block, string $name): string
@@ -422,42 +421,33 @@ private function PartialStatement(PartialStatement $statement): string
         // appendContent opcode) and invoke the partial with an empty indent so its lines are
         // not additionally indented.
         if ($this->context->options->preventIndent && $statement->indent !== '') {
-            return "$indent." . self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, ''");
+            return "$indent." . self::getRuntimeFunc('p', "\$cx, $p, $vars, ''");
         }
 
-        return self::getRuntimeFunc('p', "\$cx, $p, $vars, 0, $indent");
+        return self::getRuntimeFunc('p', "\$cx, $p, $vars, $indent");
     }
 
     private function PartialBlockStatement(PartialBlockStatement $statement): string
     {
-        $this->context->partialBlockId++;
-        $pid = $this->context->partialBlockId;
-
         // Hoist inline partial registrations so they run before the partial is called.
         // Without this, inline partials defined in the block would only be registered when
         // {{> @partial-block}} is invoked, too late for partials that call them directly.
-        $hoistedParts = [];
+        $parts = [];
         foreach ($statement->program->body as $stmt) {
             if ($stmt instanceof BlockStatement && $stmt->type === 'DecoratorBlock') {
-                $hoistedParts[] = $this->accept($stmt);
+                $parts[] = $this->accept($stmt);
             }
         }
 
         $name = $statement->name;
         $body = $this->compileProgram($statement->program);
+        $partialName = null;
+        $found = false;
 
         if ($name instanceof PathExpression || $name instanceof StringLiteral || $name instanceof NumberLiteral) {
             $partialName = $this->resolvePartialName($name);
             $p = self::quote($partialName);
-        } else {
-            $p = $this->compileExpression($name);
-            $partialName = null;
-        }
-
-        $found = false;
-
-        if ($partialName !== null) {
-            $found = isset($this->context->usedPartial[$partialName]);
+            $found = ($this->context->usedPartial[$partialName] ?? '') !== '';
 
             if (!$found && !str_starts_with($partialName, '@partial-block')) {
                 $cnt = $this->resolvePartial($partialName);
@@ -468,26 +458,23 @@ private function PartialBlockStatement(PartialBlockStatement $statement): string
                 }
             }
 
-            if (!$found) {
-                // Mark as known so LR::p() can resolve it at runtime.
-                $this->context->usedPartial[$partialName] = '';
-                // Don't add to partialCode — register via LR::in() at runtime so $blockParams
-                // is captured from the enclosing scope when block params are in use.
-            }
+            // Mark as known for runtime resolution; not added to partialCode so $blockParams scope is preserved.
+            $this->context->usedPartial[$partialName] ??= '';
+        } else {
+            $p = $this->compileExpression($name);
         }
 
         $vars = $this->compilePartialParams($statement->params, $statement->hash);
 
         // Capture $blockParams if we're inside a block-param scope so the partial block body can access them.
         $useVars = $this->blockParamsUseVars();
         $bodyClosure = self::templateClosure($body, useVars: $useVars);
-        $fallbackParts = ($partialName !== null && !$found)
-            ? [self::getRuntimeFunc('inFallback', "\$cx, " . self::quote($partialName) . ', ' . $bodyClosure)]
-            : [];
-        $parts = [...$hoistedParts, ...$fallbackParts,
-            self::getRuntimeFunc('in', "\$cx, '@partial-block$pid', " . $bodyClosure),
-            self::getRuntimeFunc('p', "\$cx, $p, $vars, $pid, ''"),
-        ];
+
+        if ($partialName !== null && !$found) {
+            // Register the block body as a fallback partial only if no runtime partial with this name exists yet.
+            $parts[] = "(isset(\$cx->partials[$p]) ? '' : " . self::getRuntimeFunc('in', "\$cx, $p, $bodyClosure") . ')';
+        }
+        $parts[] = self::getRuntimeFunc('p', "\$cx, $p, $vars, '', $bodyClosure");
         return implode('.', $parts);
     }
 
@@ -617,7 +604,7 @@ private function PathExpression(PathExpression $expression): string
 
         // @partial-block as variable: truthy when an active partial block exists
         if ($data && $depth === 0 && count($stringParts) === 1 && $stringParts[0] === 'partial-block') {
-            return "isset(\$cx->partials['@partial-block' . \$cx->partialId]) ? true : null";
+            return "\$cx->partialBlock !== null ? true : null";
         }
 
         // Check block params (depth-0, non-data, non-scoped paths only, not SubExpression-headed)
@@ -788,13 +775,8 @@ private function compilePartialTemplate(string $name, string $template): void
             return;
         }
 
-        $tmpContext = clone $this->context;
-        $tmpContext->inlinePartial = [];
-        $tmpContext->partialBlock = [];
-
         $program = $this->parser->parse($template);
-        $code = (new Compiler($this->parser))->compile($program, $tmpContext);
-        $this->context->merge($tmpContext);
+        $code = (new Compiler($this->parser))->compile($program, $this->context);
 
         $this->context->partialCode[$name] = self::quote($name) . ' => ' . self::templateClosure($code);
     }
@@ -897,13 +879,10 @@ private function compileElseClause(BlockStatement $block): string
      */
     private function buildBasePath(bool $data, int $depth): string
     {
-        $base = $data ? '$cx->frame' : '$in';
-        if ($depth > 0) {
-            $base = $data
-                ? $base . str_repeat("['_parent']", $depth)
-                : "\$cx->depths[count(\$cx->depths)-$depth]";
+        if ($data) {
+            return '$cx->frame' . str_repeat("['_parent']", $depth);
         }
-        return $base;
+        return $depth > 0 ? "\$cx->depths[count(\$cx->depths)-$depth]" : '$in';
     }
 
     /**
@@ -963,14 +942,13 @@ private static function blockClosure(string $body, bool $declaresBp = false, boo
             $preamble = '$sc=count($cx->depths);';
             $body = str_replace('$cx->depths[count($cx->depths)-', '$cx->depths[$sc-', $body);
         }
-        if ($declaresBp) {
-            return "function(\$cx, \$in, array \$blockParams = []) {{$preamble}return $body;}";
-        }
-        if ($inheritsBp) {
-            // Inherits block params from the enclosing closure's $blockParams variable.
-            return "function(\$cx, \$in) use (\$blockParams) {{$preamble}return $body;}";
-        }
-        return "function(\$cx, \$in) {{$preamble}return $body;}";
+        // Inherits block params from the enclosing closure's $blockParams variable when $inheritsBp.
+        $sig = match (true) {
+            $declaresBp => "function(\$cx, \$in, array \$blockParams = [])",
+            $inheritsBp => "function(\$cx, \$in) use (\$blockParams)",
+            default => "function(\$cx, \$in)",
+        };
+        return "$sig {{$preamble}return $body;}";
     }
 
     private static function quote(string $string): string

src/Context.php

@@ -11,33 +11,14 @@ final class Context
      * @param array<string, string> $usedPartial
      * @param array<string, string> $partialCode
      * @param array<string, string> $partials
-     * @param array<mixed> $partialBlock
-     * @param array<mixed> $inlinePartial
      */
     public function __construct(
         public readonly Options $options,
         public array $usedPartial = [],
         public array $partialCode = [],
         public int $usedDynPartial = 0,
-        public int $usedPBlock = 0,
-        public int $partialBlockId = 0,
         public array $partials = [],
-        public array $partialBlock = [],
-        public array $inlinePartial = [],
     ) {
         $this->partials = $options->partials;
     }
-
-    /**
-     * Update from another context.
-     */
-    public function merge(self $context): void
-    {
-        $this->partials = $context->partials;
-        $this->partialCode = $context->partialCode;
-        $this->usedDynPartial = $context->usedDynPartial;
-        $this->usedPBlock = $context->usedPBlock;
-        $this->partialBlockId = $context->partialBlockId;
-        $this->usedPartial = $context->usedPartial;
-    }
 }

src/Runtime.php

@@ -166,8 +166,8 @@ public static function createContext(mixed $context, array $options, array $comp
                 partials: $parentCx->partials,
                 depths: $parentCx->depths,
                 data: $root,
-                partialId: $parentCx->partialId,
                 frame: $parentCx->frame,
+                partialBlock: $parentCx->partialBlock,
             );
         }
 
@@ -366,17 +366,28 @@ public static function merge(mixed $a, mixed $b): mixed
      * @param array<string, mixed> $hash named hash overrides merged into the context
      * @param string $indent whitespace to prepend to each line of the partial's output
      */
-    public static function p(RuntimeContext $cx, string $name, mixed $context, array $hash, int $pid, string $indent): string
+    public static function p(RuntimeContext $cx, string $name, mixed $context, array $hash, string $indent, ?\Closure $partialBlock = null): string
     {
-        $pp = ($name === '@partial-block') ? $name . ($pid > 0 ? $pid : $cx->partialId) : $name;
-
-        $fn = $cx->partials[$pp] ?? null;
+        $fn = $name === '@partial-block' ? $cx->partialBlock : ($cx->partials[$name] ?? null);
         if ($fn === null) {
             throw new \Exception("The partial $name could not be found");
         }
 
-        $savedPartialId = $cx->partialId;
-        $cx->partialId = ($name === '@partial-block') ? ($pid > 0 ? $pid : ($cx->partialId > 0 ? $cx->partialId - 1 : 0)) : $pid;
+        // Install a wrapper as the active @partial-block so the partial can invoke it via {{> @partial-block}}.
+        // The wrapper temporarily restores the previously active block before calling $partialBlock,
+        // allowing nested partial blocks to correctly resolve their own @partial-block.
+        if ($partialBlock !== null) {
+            $currentBlock = $cx->partialBlock;
+            $cx->partialBlock = static function (mixed $blockContext) use ($partialBlock, $currentBlock): string {
+                $callingCx = self::$partialContext;
+                assert($callingCx !== null);
+                $saved = $callingCx->partialBlock;
+                $callingCx->partialBlock = $currentBlock;
+                $result = $partialBlock($blockContext);
+                $callingCx->partialBlock = $saved;
+                return $result;
+            };
+        }
 
         $context = $hash ? static::merge($context, $hash) : $context;
         $prev = self::$partialContext;
@@ -385,8 +396,10 @@ public static function p(RuntimeContext $cx, string $name, mixed $context, array
             $result = $fn($context);
         } finally {
             self::$partialContext = $prev;
+            if ($partialBlock !== null) {
+                $cx->partialBlock = $currentBlock;
+            }
         }
-        $cx->partialId = $savedPartialId;
 
         if ($indent !== '') {
             $lines = explode("\n", $result);
@@ -405,43 +418,14 @@ public static function p(RuntimeContext $cx, string $name, mixed $context, array
     }
 
     /**
-     * Like in() but only registers the partial if it is not already present in the context.
-     * Used for {{#> partial}}fallback{{/partial}} blocks when the partial was not found at compile time.
-     *
-     * @param string $name partial name
-     * @param \Closure $partial the compiled fallback partial
-     */
-    public static function inFallback(RuntimeContext $cx, string $name, \Closure $partial): string
-    {
-        $cx->partials[$name] ??= $partial;
-        return '';
-    }
-
-    /**
-     * For {{#* inlinepartial}} .
+     * For {{#* inline "name"}} and {{#> partial}}fallback{{/partial}} blocks.
      *
      * @param string $name partial name
      * @param \Closure $partial the compiled partial
      */
     public static function in(RuntimeContext $cx, string $name, \Closure $partial): string
     {
-        if (str_starts_with($name, '@partial-block')) {
-            // Capture the outer partialId at registration time so that when this
-            // block closure runs, any {{>@partial-block}} inside it resolves to
-            // the correct outer partial block rather than following the pid-decrement chain.
-            $outerPartialId = $cx->partialId;
-            $cx->partials[$name] = function (mixed $context = null, array $options = []) use ($partial, $outerPartialId): string {
-                $callingCx = self::$partialContext;
-                assert($callingCx !== null);
-                $savedId = $callingCx->partialId;
-                $callingCx->partialId = $outerPartialId;
-                $result = $partial($context, $options);
-                $callingCx->partialId = $savedId;
-                return $result;
-            };
-        } else {
-            $cx->partials[$name] = $partial;
-        }
+        $cx->partials[$name] = $partial;
         return '';
     }
 

src/RuntimeContext.php

@@ -19,7 +19,7 @@ public function __construct(
         public array $partials = [],
         public array $depths = [],
         public array $data = [],
-        public int $partialId = 0,
         public array $frame = [],
+        public ?\Closure $partialBlock = null,
     ) {}
 }