Remove trivial cases of unreachable code

Summary:
Static code analysis can detect `Unreachable statement - code above always terminates.`
The vast majority of occurrences in the Arcanist codebase are due to an unreachable `break` within a `case` after a `return` or after an all-covering `if/else`.
All this noise makes it harder to spot real logic issues (there are some!), thus fix these trivial cases.

Test Plan: Examine the code; run static code analysis.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25803

src/configuration/ArcanistSettings.php

@@ -236,7 +236,6 @@ final class ArcanistSettings extends Phobject {
         throw new Exception(
           pht(
             'Use "arc alias" to configure aliases, not "arc set-config".'));
-        break;
 
     }
 

src/parser/PhutilTypeSpec.php

@@ -336,7 +336,6 @@ final class PhutilTypeSpec extends Phobject {
           $obj->subtypes[] = $r;
           return $obj;
         }
-        break;
       case 'map_type':
         $obj = new PhutilTypeSpec();
         $obj->type = 'map';
@@ -355,7 +354,6 @@ final class PhutilTypeSpec extends Phobject {
         } else {
           return $tokens[0];
         }
-        break;
       case 'maybe_comment':
         if ($production == 'yes') {
           $tokens[0]->comment = $tokens[1];

src/parser/__tests__/ArcanistDiffParserTestCase.php

@@ -610,7 +610,6 @@ EOTEXT
         break;
       default:
         throw new Exception(pht('No test block for diff file %s.', $diff_file));
-        break;
     }
   }
 

src/parser/xhpast/api/XHPASTNode.php

@@ -31,7 +31,6 @@ final class XHPASTNode extends AASTNode {
     switch ($this->getTypeName()) {
       case 'n_STATEMENT':
         return $this->getChildByIndex(0)->evalStatic();
-        break;
       case 'n_STRING_SCALAR':
         return phutil_string_cast($this->getStringLiteralValue());
       case 'n_HEREDOC':
@@ -61,22 +60,18 @@ final class XHPASTNode extends AASTNode {
           default:
             throw new Exception(pht('Unrecognized symbol name.'));
         }
-        break;
       case 'n_UNARY_PREFIX_EXPRESSION':
         $operator = $this->getChildOfType(0, 'n_OPERATOR');
         $operand = $this->getChildByIndex(1);
         switch ($operator->getSemanticString()) {
           case '-':
             return -$operand->evalStatic();
-            break;
           case '+':
             return $operand->evalStatic();
-            break;
           default:
             throw new Exception(
               pht('Unexpected operator in static expression.'));
         }
-        break;
       case 'n_ARRAY_LITERAL':
         $result = array();
         $values = $this->getChildOfType(0, 'n_ARRAY_VALUE_LIST');

src/xsprintf/tsprintf.php

@@ -68,7 +68,6 @@ function xsprintf_terminal($userdata, &$pattern, &$pos, &$value, &$length) {
           'Unsupported escape sequence "%s" found in pattern: %s',
           $type,
           $pattern));
-      break;
   }
 
   $pattern[$pos] = $type;