fix(compiler): preserve PHP switch comparison semantics (#89)

src/Parser/SwitchTrait.php

@@ -38,11 +38,29 @@ trait SwitchTrait
         $var_def .= $type . ' ' . $tmp_var . ' = ' . $condExpr . ';' . PHP_EOL;
         $var_def .= $this->formatCapturedStmtLines($condAfterStmts);
 
-        // Save the scope; switch parsing may fail partway and add variables in the process, so it must be reset
-        $localVars = $this->context->localVars;
-        $code      = $this->parseBeforeStmtLines() . PHP_EOL;
+        $code = $this->parseBeforeStmtLines() . PHP_EOL;
 
         if ($type === Type::INT or $type === Type::BOOL) {
+            // Check all labels before lowering any bodies. C++ requires integer
+            // labels; for bool subjects, only 0 and 1 preserve PHP comparison.
+            $nativeCaseValues = [];
+            foreach ($v->cases as $case) {
+                $caseCond = $case->cond;
+                if ($caseCond === null) {
+                    continue;
+                }
+                if (!$caseCond instanceof Node\Scalar\Int_
+                    || ($type === Type::BOOL && $caseCond->value !== 0 && $caseCond->value !== 1)
+                ) {
+                    goto _fail;
+                }
+                if (isset($nativeCaseValues[$caseCond->value])) {
+                    // PHP permits duplicate case values and selects the first
+                    // matching label, while C++ rejects duplicate case labels.
+                    goto _fail;
+                }
+                $nativeCaseValues[$caseCond->value] = true;
+            }
             $code .= 'do {' . PHP_EOL;
             $this->indentLevel++;
             $code .= $this->getIndent() . 'switch (' . $tmp_var . ') {' . PHP_EOL;
@@ -51,12 +69,6 @@ trait SwitchTrait
                 if (empty($case->cond)) {
                     $code .= $this->getIndent() . 'default: {' . PHP_EOL;
                 } else {
-                    $condType = $case->cond->getType();
-                    if ($condType !== 'Scalar_Int' and $condType !== 'Scalar_Float') {
-                        $this->context->localVars = $localVars;
-                        $this->indentLevel -= 2;
-                        goto _fail;
-                    }
                     $code .= $this->getIndent() . 'case ' . $this->parseScalar($case->cond) . ': {' . PHP_EOL;
                 }
                 $code .= $this->parseBlockStmts($case->stmts);
@@ -135,6 +147,9 @@ trait SwitchTrait
                         $code .= $this->formatCapturedStmtLines($caseAfterStmts);
                         $caseCondExpr = $caseTmpVar;
                     }
+                    if ($type === Type::BOOL) {
+                        $caseCondExpr = 'php::toBool(' . $caseCondExpr . ')';
+                    }
                     $code .= $this->getIndent() . $groupMatched . ' = php::equals(' . $tmp_var . ', ' . $caseCondExpr . ');' . PHP_EOL;
                     $code .= $this->getIndent() . '}' . PHP_EOL;
                 }

tests/compiler/switch/bool-numeric-case.phpt

@@ -0,0 +1,40 @@
+--TEST--
+Boolean switch subjects use PHP loose comparison for numeric cases
+--FILE--
+<?php
+function select_bool(bool $value): string
+{
+    switch ($value) {
+        case 2:
+            return 'nonzero';
+        case 0:
+            return 'zero';
+        default:
+            return 'default';
+    }
+}
+
+function select_binary_bool(bool $value): string
+{
+    switch ($value) {
+        case 0:
+            return 'false';
+        case 1:
+            return 'true';
+    }
+    return 'default';
+}
+
+function main(): void
+{
+    echo select_bool(true), "\n";
+    echo select_bool(false), "\n";
+    echo select_binary_bool(true), "\n";
+    echo select_binary_bool(false), "\n";
+}
+?>
+--EXPECT--
+nonzero
+zero
+true
+false

tests/compiler/switch/duplicate-integer-case.phpt

@@ -0,0 +1,41 @@
+--TEST--
+Duplicate integer switch cases retain PHP first-match semantics
+--FILE--
+<?php
+function select_duplicate_int(int $value): string
+{
+    switch ($value) {
+        case 1:
+            return 'first-int';
+        case 1:
+            return 'second-int';
+        default:
+            return 'default-int';
+    }
+}
+
+function select_duplicate_bool(bool $value): string
+{
+    switch ($value) {
+        case 1:
+            return 'first-bool';
+        case 1:
+            return 'second-bool';
+        default:
+            return 'default-bool';
+    }
+}
+
+function main(): void
+{
+    echo select_duplicate_int(1), "\n";
+    echo select_duplicate_int(2), "\n";
+    echo select_duplicate_bool(true), "\n";
+    echo select_duplicate_bool(false), "\n";
+}
+?>
+--EXPECT--
+first-int
+default-int
+first-bool
+default-bool

tests/compiler/switch/int-float-case.phpt

@@ -0,0 +1,29 @@
+--TEST--
+Integer switch subjects accept floating-point case labels
+--FILE--
+<?php
+function select_number(int $value): string
+{
+    switch ($value) {
+        case 0:
+            return 'zero';
+        case 1.5:
+            return 'fraction';
+        case 2.0:
+            return 'two';
+        default:
+            return 'default';
+    }
+}
+
+function main(): void
+{
+    echo select_number(0), "\n";
+    echo select_number(1), "\n";
+    echo select_number(2), "\n";
+}
+?>
+--EXPECT--
+zero
+default
+two