Add test coverage for GMP operator overloads and gmp_* functions

This adds comprehensive type inference tests for GMP operations:

- Arithmetic operators (+, -, *, /, %, **) with GMP on left and right
- Bitwise operators (&, |, ^, ~, <<, >>) with GMP on left and right
- Comparison operators (<, <=, >, >=, ==, !=, <=>) with GMP on left and right
- Assignment operators (+=, -=, *=)
- Corresponding gmp_* functions (gmp_add, gmp_sub, gmp_mul, etc.)

These tests currently fail because PHPStan lacks a GmpOperatorTypeSpecifyingExtension
to specify that GMP operations return GMP rather than int|float.

Related: phpstan/phpstan#12123

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: Firehed

tests/PHPStan/Analyser/nsrt/gmp-operators.php

@@ -0,0 +1,192 @@
+<?php
+
+namespace GmpOperatorsTest;
+
+use function PHPStan\Testing\assertType;
+
+// =============================================================================
+// Operator overloads
+// =============================================================================
+
+function gmpArithmeticOperators(\GMP $a, \GMP $b): void
+{
+	assertType('GMP', $a + $b);
+	assertType('GMP', $a - $b);
+	assertType('GMP', $a * $b);
+	assertType('GMP', $a / $b);
+	assertType('GMP', $a % $b);
+	assertType('GMP', $a ** $b);
+	assertType('GMP', -$a);
+}
+
+function gmpWithIntOperators(\GMP $a, int $i): void
+{
+	// GMP on left
+	assertType('GMP', $a + $i);
+	assertType('GMP', $a - $i);
+	assertType('GMP', $a * $i);
+	assertType('GMP', $a / $i);
+	assertType('GMP', $a % $i);
+	assertType('GMP', $a ** $i);
+
+	// int on left (GMP on right)
+	assertType('GMP', $i + $a);
+	assertType('GMP', $i - $a);
+	assertType('GMP', $i * $a);
+	assertType('GMP', $i / $a);
+	assertType('GMP', $i % $a);
+	// Note: $i ** $a is not supported by GMP - exponent must be int
+}
+
+function gmpBitwiseOperators(\GMP $a, \GMP $b, int $i): void
+{
+	// GMP bitwise with GMP
+	assertType('GMP', $a & $b);
+	assertType('GMP', $a | $b);
+	assertType('GMP', $a ^ $b);
+	assertType('GMP', ~$a);
+	assertType('GMP', $a << $b);
+	assertType('GMP', $a >> $b);
+
+	// GMP on left, int on right
+	assertType('GMP', $a & $i);
+	assertType('GMP', $a | $i);
+	assertType('GMP', $a ^ $i);
+	assertType('GMP', $a << $i);
+	assertType('GMP', $a >> $i);
+
+	// int on left, GMP on right
+	assertType('GMP', $i & $a);
+	assertType('GMP', $i | $a);
+	assertType('GMP', $i ^ $a);
+}
+
+function gmpComparisonOperators(\GMP $a, \GMP $b, int $i): void
+{
+	// GMP compared with GMP
+	assertType('bool', $a < $b);
+	assertType('bool', $a <= $b);
+	assertType('bool', $a > $b);
+	assertType('bool', $a >= $b);
+	assertType('bool', $a == $b);
+	assertType('bool', $a != $b);
+	assertType('int<-1, 1>', $a <=> $b);
+
+	// GMP on left, int on right
+	assertType('bool', $a < $i);
+	assertType('bool', $a <= $i);
+	assertType('bool', $a > $i);
+	assertType('bool', $a >= $i);
+	assertType('bool', $a == $i);
+	assertType('bool', $a != $i);
+	assertType('int<-1, 1>', $a <=> $i);
+
+	// int on left, GMP on right
+	assertType('bool', $i < $a);
+	assertType('bool', $i <= $a);
+	assertType('bool', $i > $a);
+	assertType('bool', $i >= $a);
+	assertType('bool', $i == $a);
+	assertType('bool', $i != $a);
+	assertType('int<-1, 1>', $i <=> $a);
+}
+
+function gmpAssignmentOperators(\GMP $a, int $i): void
+{
+	$x = $a;
+	$x += $i;
+	assertType('GMP', $x);
+
+	$y = $a;
+	$y -= $i;
+	assertType('GMP', $y);
+
+	$z = $a;
+	$z *= $i;
+	assertType('GMP', $z);
+}
+
+// =============================================================================
+// gmp_* functions (corresponding to operator overloads)
+// =============================================================================
+
+function gmpArithmeticFunctions(\GMP $a, \GMP $b, int $i): void
+{
+	// gmp_add corresponds to +
+	assertType('GMP', gmp_add($a, $b));
+	assertType('GMP', gmp_add($a, $i));
+	assertType('GMP', gmp_add($i, $a));
+
+	// gmp_sub corresponds to -
+	assertType('GMP', gmp_sub($a, $b));
+	assertType('GMP', gmp_sub($a, $i));
+	assertType('GMP', gmp_sub($i, $a));
+
+	// gmp_mul corresponds to *
+	assertType('GMP', gmp_mul($a, $b));
+	assertType('GMP', gmp_mul($a, $i));
+	assertType('GMP', gmp_mul($i, $a));
+
+	// gmp_div_q corresponds to /
+	assertType('GMP', gmp_div_q($a, $b));
+	assertType('GMP', gmp_div_q($a, $i));
+
+	// gmp_div is alias of gmp_div_q
+	assertType('GMP', gmp_div($a, $b));
+
+	// gmp_mod corresponds to %
+	assertType('GMP', gmp_mod($a, $b));
+	assertType('GMP', gmp_mod($a, $i));
+
+	// gmp_pow corresponds to **
+	assertType('GMP', gmp_pow($a, 2));
+	assertType('GMP', gmp_pow($a, $i));
+
+	// gmp_neg corresponds to unary -
+	assertType('GMP', gmp_neg($a));
+
+	// gmp_abs (no direct operator)
+	assertType('GMP', gmp_abs($a));
+}
+
+function gmpBitwiseFunctions(\GMP $a, \GMP $b): void
+{
+	// gmp_and corresponds to &
+	assertType('GMP', gmp_and($a, $b));
+
+	// gmp_or corresponds to |
+	assertType('GMP', gmp_or($a, $b));
+
+	// gmp_xor corresponds to ^
+	assertType('GMP', gmp_xor($a, $b));
+
+	// gmp_com corresponds to ~
+	assertType('GMP', gmp_com($a));
+}
+
+function gmpComparisonFunctions(\GMP $a, \GMP $b, int $i): void
+{
+	// gmp_cmp corresponds to <=>
+	assertType('int<-1, 1>', gmp_cmp($a, $b));
+	assertType('int<-1, 1>', gmp_cmp($a, $i));
+}
+
+function gmpFromInit(): void
+{
+	$x = gmp_init('1');
+	assertType('GMP', $x);
+
+	// Operator with gmp_init result
+	$y = $x * 2;
+	assertType('GMP', $y);
+
+	$z = $x + gmp_init('5');
+	assertType('GMP', $z);
+}
+
+function gmpWithNumericString(\GMP $a, string $s): void
+{
+	// GMP functions accept numeric strings
+	assertType('GMP', gmp_add($a, '123'));
+	assertType('GMP', gmp_mul($a, '456'));
+}