Tokenizer: Simplify 'while (0)' better

lib/tokenize.cpp

@@ -2214,6 +2214,7 @@ bool Tokenizer::simplifyTokenList()
     simplifyIfNotNull();
     simplifyComparisonOrder();
     simplifyNestedStrcat();
+    simplifyWhile0();
 
     for (Token *tok = _tokens; tok; tok = tok->next())
     {
@@ -4957,3 +4958,43 @@ void Tokenizer::getErrorMessages()
 {
     syntaxError(0, ' ');
 }
+
+void Tokenizer::simplifyWhile0()
+{
+    for (Token *tok = _tokens; tok; tok = tok->next())
+    {
+        if (!Token::simpleMatch(tok, "while ( 0 )"))
+            continue;
+
+        // remove "while (0) { .. }"
+        if (Token::simpleMatch(tok->tokAt(4), "{"))
+        {
+            Token::eraseTokens(tok, tok->tokAt(4)->link());
+            tok->deleteThis();  // delete "while"
+            tok->deleteThis();  // delete "}"
+        }
+
+        if (Token::simpleMatch(tok->previous(), "}"))
+        {
+            // find "do"
+            Token *tok2 = tok->previous()->link();
+            tok2 = tok2 ? tok2->previous() : 0;
+            if (tok2 && tok2->str() == "do")
+            {
+                // delete "do {"
+                tok2->deleteThis();
+                tok2->deleteThis();
+
+                // delete "} while ( 0 )"
+                tok = tok->previous();
+                tok->deleteNext();  // while
+                tok->deleteNext();  // (
+                tok->deleteNext();  // 0
+                tok->deleteNext();  // )
+                tok->deleteThis();  // }
+
+                continue;
+            }
+        }
+    }
+}

lib/tokenize.h

@@ -320,6 +320,11 @@ private:
      */
     void simplifyConst();
 
+    /**
+     * simplify "while (0)"
+     */
+    void simplifyWhile0();
+
     /**
      * Remove exception specifications. This function calls itself recursively.
      * @param tok First token in scope to cleanup

test/testsimplifytokens.cpp

@@ -149,6 +149,9 @@ private:
         TEST_CASE(pointeralias);
 
         TEST_CASE(reduceConstness);
+
+        // simplify "while (0)"
+        TEST_CASE(while0);
     }
 
     std::string tok(const char code[], bool simplify = true)
@@ -991,7 +994,7 @@ private:
                             "    sizeof 1;\n"
                             "    while (0);\n"
                             "}\n";
-        ASSERT_EQUALS("void f ( ) { sizeof ( 1 ) ; while ( false ) { ; } }", tok(code));
+        ASSERT_EQUALS("void f ( ) { sizeof ( 1 ) ; }", tok(code));
         ASSERT_EQUALS("", errout.str());
     }
 
@@ -2498,6 +2501,11 @@ private:
     {
         ASSERT_EQUALS("char * p ;", tok("char * const p;"));
     }
+
+    void while0()
+    {
+        ASSERT_EQUALS("; x = 1 ; ;", tok("; do { x = 1 ; } while (0);"));
+    }
 };
 
 REGISTER_TEST(TestSimplifyTokens)

test/testtokenize.cpp

@@ -65,7 +65,6 @@ private:
         TEST_CASE(ifAddBraces5);
         TEST_CASE(ifAddBraces6);
         TEST_CASE(ifAddBraces7);
-        TEST_CASE(ifAddBraces8);
         TEST_CASE(ifAddBraces9);
 
         TEST_CASE(whileAddBraces);
@@ -575,12 +574,6 @@ private:
                       "}", tokenizeAndStringify(code, true));
     }
 
-    void ifAddBraces8()
-    {
-        const char code[] = "do { ; } while(0);";
-        ASSERT_EQUALS("do { ; } while ( false ) ;", tokenizeAndStringify(code, true));
-    }
-
     void ifAddBraces9()
     {
         // ticket #990
@@ -610,9 +603,9 @@ private:
     {
         {
             const char code[] = "do ; while (0);";
-            const char result[] = "do { ; } while ( false ) ;";
+            const char result[] = "do { ; } while ( 0 ) ;";
 
-            ASSERT_EQUALS(result, tokenizeAndStringify(code, true));
+            ASSERT_EQUALS(result, tokenizeAndStringify(code, false));
         }
 
         {