fix skipping of cpp attributes. (#4971)

* fix skipping of cpp attributes.

* fix simplifyCPPAttribute loop.

When the first token was the start of a c++ attribute on a function,
so that tok->previous() was nullptr at the bottom of the loop,
an extra token would be skipped.  This could result in the corresponding
function being omitted from the symbol table.

* fix alignas test failure, enhance cpp attr test.

* uncrustify.

* fix redundantNextPrevious

* delete redundant code.

* add some tokenizer tests for simplifyCPPAttribute.

* enhance noreturn symbol test.

The order of a noreturn attribute and another attribute used to
matter.  Test both orders.

lib/tokenize.cpp

@@ -8825,36 +8825,35 @@ void Tokenizer::simplifyCPPAttribute()
     if (mSettings->standards.cpp < Standards::CPP11 || isC())
         return;
 
-    for (Token *tok = list.front(); tok; tok = tok->next()) {
+    for (Token *tok = list.front(); tok;) {
         if (!isCPPAttribute(tok) && !isAlignAttribute(tok)) {
+            tok = tok->next();
             continue;
         }
         if (isCPPAttribute(tok)) {
             if (Token::findsimplematch(tok->tokAt(2), "noreturn", tok->link())) {
-                Token * head = skipCPPOrAlignAttribute(tok);
+                Token * head = skipCPPOrAlignAttribute(tok)->next();
                 while (isCPPAttribute(head) || isAlignAttribute(head))
-                    head = skipCPPOrAlignAttribute(head);
+                    head = skipCPPOrAlignAttribute(head)->next();
-                head = head->next();
                 while (Token::Match(head, "%name%|::|*|&|<|>|,")) // skip return type
                     head = head->next();
                 if (head && head->str() == "(" && isFunctionHead(head, "{|;")) {
                     head->previous()->isAttributeNoreturn(true);
                 }
             } else if (Token::findsimplematch(tok->tokAt(2), "nodiscard", tok->link())) {
-                Token * head = skipCPPOrAlignAttribute(tok);
+                Token * head = skipCPPOrAlignAttribute(tok)->next();
                 while (isCPPAttribute(head) || isAlignAttribute(head))
-                    head = skipCPPOrAlignAttribute(head);
+                    head = skipCPPOrAlignAttribute(head)->next();
-                head = head->next();
                 while (Token::Match(head, "%name%|::|*|&|<|>|,"))
                     head = head->next();
                 if (head && head->str() == "(" && isFunctionHead(head, "{|;")) {
                     head->previous()->isAttributeNodiscard(true);
                 }
             } else if (Token::findsimplematch(tok->tokAt(2), "maybe_unused", tok->link())) {
-                Token* head = skipCPPOrAlignAttribute(tok);
+                Token* head = skipCPPOrAlignAttribute(tok)->next();
                 while (isCPPAttribute(head) || isAlignAttribute(head))
-                    head = skipCPPOrAlignAttribute(head);
+                    head = skipCPPOrAlignAttribute(head)->next();
-                head->next()->isAttributeMaybeUnused(true);
+                head->isAttributeMaybeUnused(true);
             } else if (Token::Match(tok->previous(), ") [ [ expects|ensures|assert default|audit|axiom| : %name% <|<=|>|>= %num% ] ]")) {
                 const Token *vartok = tok->tokAt(4);
                 if (vartok->str() == ":")
@@ -8884,14 +8883,7 @@ void Tokenizer::simplifyCPPAttribute()
             }
         }
         Token::eraseTokens(tok, skipCPPOrAlignAttribute(tok)->next());
-        // fix iterator after removing
+        tok->deleteThis();
-        if (tok->previous()) {
-            tok = tok->previous();
-            tok->next()->deleteThis();
-        } else {
-            tok->deleteThis();
-            tok = list.front();
-        }
     }
 }
 

test/testsymboldatabase.cpp

@@ -7408,7 +7408,10 @@ private:
                       "void func1() { }\n"
                       "[[noreturn]] void func2();\n"
                       "[[noreturn]] void func3() { }\n"
-                      "template <class T> [[noreturn]] void func4() { }");
+                      "template <class T> [[noreturn]] void func4() { }\n"
+                      "[[noreturn]] [[gnu::format(printf, 1, 2)]] void func5(const char*, ...);\n"
+                      "[[gnu::format(printf, 1, 2)]] [[noreturn]] void func6(const char*, ...);\n"
+                      );
         ASSERT_EQUALS("", errout.str());
         ASSERT_EQUALS(true,  db != nullptr); // not null
 
@@ -7428,6 +7431,14 @@ private:
         ASSERT_EQUALS(true, func != nullptr);
         ASSERT_EQUALS(true, func->isAttributeNoreturn());
 
+        func = findFunctionByName("func5", &db->scopeList.front());
+        ASSERT_EQUALS(true, func != nullptr);
+        ASSERT_EQUALS(true, func->isAttributeNoreturn());
+
+        func = findFunctionByName("func6", &db->scopeList.front());
+        ASSERT_EQUALS(true, func != nullptr);
+        ASSERT_EQUALS(true, func->isAttributeNoreturn());
+
     }
 
     void nodiscardAttributeFunction() {

test/testtokenize.cpp

@@ -5691,6 +5691,24 @@ private:
 
         ASSERT_EQUALS("struct a ;",
                       tokenizeAndStringify("struct [[deprecated,maybe_unused]] alignas(double) [[trivial_abi]] a;"));
+
+        ASSERT_EQUALS("void func5 ( const char * , ... ) ;",
+                      tokenizeAndStringify("[[noreturn]] void func5(const char*, ...);"));
+
+        ASSERT_EQUALS("void func5 ( const char * , ... ) ;",
+                      tokenizeAndStringify("[[noreturn]] [[gnu::format(printf, 1, 2)]] void func5(const char*, ...);"));
+
+        ASSERT_EQUALS("void func5 ( const char * , ... ) ;",
+                      tokenizeAndStringify("[[gnu::format(printf, 1, 2)]] [[noreturn]] void func5(const char*, ...);"));
+
+        ASSERT_EQUALS("int func1 ( ) ;",
+                      tokenizeAndStringify("[[nodiscard]] int func1();"));
+
+        ASSERT_EQUALS("int func1 ( ) ;",
+                      tokenizeAndStringify("[[nodiscard]] [[clang::optnone]] int func1();"));
+
+        ASSERT_EQUALS("int func1 ( ) ;",
+                      tokenizeAndStringify("[[clang::optnone]] [[nodiscard]] int func1();"));
     }
 
     void simplifyCaseRange() {