Add explicit limits to unit test/lint error names

Summary:
Fixes T12981.

See new `arc lint` output: P2071

See new `arc unit` output: P2072

Test Plan: Ran `arc unit/lint/diff` and observed new error instead of a Conduit error

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12981

Differential Revision: https://secure.phabricator.com/D18603

src/lint/ArcanistLintMessage.php

@@ -126,6 +126,21 @@ public function getSeverity() {
   }
 
   public function setName($name) {
+    $maximum_bytes = 255;
+    $actual_bytes = strlen($name);
+
+    if ($actual_bytes > $maximum_bytes) {
+      throw new Exception(
+        pht(
+          'Parameter ("%s") passed to "%s" when constructing a lint message '.
+          'must be a string with a maximum length of %s bytes, but is %s '.
+          'bytes in length.',
+          $name,
+          'setName()',
+          new PhutilNumber($maximum_bytes),
+          new PhutilNumber($actual_bytes)));
+    }
+
     $this->name = $name;
     return $this;
   }

src/unit/ArcanistUnitTestResult.php

@@ -30,6 +30,20 @@ public function getNamespace() {
   }
 
   public function setName($name) {
+    $maximum_bytes = 255;
+    $actual_bytes = strlen($name);
+
+    if ($actual_bytes > $maximum_bytes) {
+      throw new Exception(
+        pht(
+          'Parameter ("%s") passed to "%s" when constructing a unit test '.
+          'message must be a string with a maximum length of %s bytes, but '.
+          'is %s bytes in length.',
+          $name,
+          'setName()',
+          new PhutilNumber($maximum_bytes),
+          new PhutilNumber($actual_bytes)));
+    }
     $this->name = $name;
     return $this;
   }