feat(resolver): add support for interface constant resolution in traits, Fix GH-112

src/Resolver/ClassConstantValueTrait.php

@@ -69,6 +69,19 @@ trait ClassConstantValueTrait
                     : $value;
             }
         }
+        if ($this->hasInterface($class)) {
+            $constant = $this->findCompileTimeInterfaceConstant($class, $name);
+            if ($constant !== null) {
+                [$interface, $constantDef] = $constant;
+                return $this->evaluateCompileTimeClassConstant(
+                    $expr,
+                    $interface,
+                    $constantDef,
+                    $name,
+                    $interface,
+                );
+            }
+        }
         [$inheritedFound, $inherited] = $this->resolveInheritedClassConst($class, $name);
         if ($inheritedFound) {
             return $inherited;

tests/compiler/const/interface-const-property-default.phpt

@@ -0,0 +1,70 @@
+--TEST--
+Interface constants can initialize properties composed from a trait
+--FILE--
+<?php
+namespace Issue112 {
+    interface BaseOutputInterface
+    {
+        public const VERBOSITY_QUIET = 16;
+    }
+
+    interface OutputInterface extends BaseOutputInterface
+    {
+        public const VERBOSITY_NORMAL = 32;
+        public const VERBOSITY_VERBOSE = 64;
+        public const VERBOSITY_VERY_VERBOSE = 128;
+        public const VERBOSITY_DEBUG = 256;
+    }
+
+    trait InteractsWithIO
+    {
+        protected int $verbosity = OutputInterface::VERBOSITY_NORMAL;
+
+        protected array $verbosityMap = [
+            'v' => OutputInterface::VERBOSITY_VERBOSE,
+            'vv' => OutputInterface::VERBOSITY_VERY_VERBOSE,
+            'vvv' => OutputInterface::VERBOSITY_DEBUG,
+            'quiet' => OutputInterface::VERBOSITY_QUIET,
+            'normal' => OutputInterface::VERBOSITY_NORMAL,
+        ];
+
+        public function getVerbosity(): int
+        {
+            return $this->verbosity;
+        }
+
+        public function getVerbosityMap(): array
+        {
+            return $this->verbosityMap;
+        }
+    }
+
+    class Command
+    {
+        use InteractsWithIO;
+    }
+}
+
+namespace {
+    function main(): void
+    {
+        $command = new Issue112\Command();
+        var_dump($command->getVerbosity());
+        var_dump($command->getVerbosityMap());
+    }
+}
+?>
+--EXPECT--
+int(32)
+array(5) {
+  ["v"]=>
+  int(64)
+  ["vv"]=>
+  int(128)
+  ["vvv"]=>
+  int(256)
+  ["quiet"]=>
+  int(16)
+  ["normal"]=>
+  int(32)
+}