Fix defaulted and deleted functions (#4540)

* Fix 9392, but for destructors: out-of-line defaulted destructors skipped everything after

Context:
```
struct S {
    ~S();
};

S::~S() = default;

void g() {
    int j;
    ++j;
}
```
Everything after `S::~S() = default;` was skipped, so the uninitialized variables in g() weren't found.

Out-of-line destructors are useful e.g. when you have a forward declared unique_ptr in the .h,
and `= default` the destructor in the .cpp, so only the cpp needs to know the header for destructing
your unique_ptr (like in the pImpl-idiom)

* Fix unit test, by correctly fixing 10789

Previous commit broke this test, but also provided the tools for a cleaner fix

* Document current behaviour

* Rewrite control flow

* Fix deleted functions, which skipped everything after

`a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction,
which sets tok to nullptr, effectively skipping to the end of the stream.

* Remove troublesome nullptr, which skips every analysis afterwards

It was introduced in 0746c241 to fix a memory leak.
But setting tok to nullptr, effectively skipping to the end, seems not needed.

Previous commits fixes prevented some cases where you could enter the `else`.
This commit is more of a fall back.

* fixup! Fix deleted functions, which skipped everything after

`a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction,
which sets tok to nullptr, effectively skipping to the end of the stream.

* fixup! Fix deleted functions, which skipped everything after

`a::b f() = delete` triggered the final else in SymbolDatabase::addNewFunction,
which sets tok to nullptr, effectively skipping to the end of the stream.

* Make it heard when encountering unexpected syntax/tokens

Co-authored-by: Gerbo Engels <gerbo.engels@ortec-finance.com>

lib/checkmemoryleak.cpp

@@ -577,14 +577,12 @@ void CheckMemoryLeakInClass::variable(const Scope *scope, const Token *tokVarnam
         const bool constructor = func.isConstructor();
         const bool destructor = func.isDestructor();
         if (!func.hasBody()) {
-            if (destructor) { // implementation for destructor is not seen => assume it deallocates all variables properly
+            if (destructor && !func.isDefault()) { // implementation for destructor is not seen and not defaulted => assume it deallocates all variables properly
                 deallocInDestructor = true;
                 memberDealloc = CheckMemoryLeak::Many;
             }
             continue;
         }
-        if (!func.functionScope) // defaulted destructor
-            continue;
         bool body = false;
         const Token *end = func.functionScope->bodyEnd;
         for (const Token *tok = func.arg->link(); tok != end; tok = tok->next()) {

lib/symboldatabase.cpp

@@ -3167,10 +3167,6 @@ void SymbolDatabase::addClassFunction(Scope **scope, const Token **tok, const To
                 Function * func = const_cast<Function *>(it->second);
                 if (!func->hasBody()) {
                     if (func->argsMatch(scope1, func->argDef, (*tok)->next(), path, path_length)) {
-                        if (func->type == Function::eDestructor && destructor) {
-                            func->hasBody(true);
-                        } else if (func->type != Function::eDestructor && !destructor) {
-                            // normal function?
                         const Token *closeParen = (*tok)->next()->link();
                         if (closeParen) {
                             const Token *eq = mTokenizer->isFunctionHead(closeParen, ";");
@@ -3178,7 +3174,10 @@ void SymbolDatabase::addClassFunction(Scope **scope, const Token **tok, const To
                                 func->isDefault(true);
                                 return;
                             }
-
+                            if (func->type == Function::eDestructor && destructor) {
+                                func->hasBody(true);
+                            } else if (func->type != Function::eDestructor && !destructor) {
+                                // normal function?
                                 const bool hasConstKeyword = closeParen->next()->str() == "const";
                                 if ((func->isConst() == hasConstKeyword) &&
                                     (func->hasLvalRefQualifier() == lval) &&
@@ -3234,22 +3233,17 @@ void SymbolDatabase::addNewFunction(Scope **scope, const Token **tok)
 
         // syntax error?
         if (!newScope->bodyEnd) {
-            scopeList.pop_back();
+            mTokenizer->unmatchedToken(tok1);
-            while (tok1->next())
+        } else {
-                tok1 = tok1->next();
-            *scope = nullptr;
-            *tok = tok1;
-            return;
-        }
-
             (*scope)->nestedList.push_back(newScope);
             *scope = newScope;
-        *tok = tok1;
-    } else {
-        scopeList.pop_back();
-        *scope = nullptr;
-        *tok = nullptr;
         }
+    } else if (tok1 && Token::Match(tok1->tokAt(-2), "= default|delete ;")) {
+        scopeList.pop_back();
+    } else {
+        throw InternalError(*tok, "Analysis failed (function not recognized). If the code is valid then please report this failure.");
+    }
+    *tok = tok1;
 }
 
 bool Type::isClassType() const

lib/tokenlist.cpp

@@ -1613,7 +1613,7 @@ static Token * createAstAtToken(Token *tok, bool cpp)
             Token::Match(typetok->previous(), "%name% ( !!*") &&
             typetok->previous()->varId() == 0 &&
             !typetok->previous()->isKeyword() &&
-            Token::Match(typetok->link(), ") const|;|{"))
+            (Token::Match(typetok->link(), ") const|;|{") || Token::Match(typetok->link(), ") const| = delete ;")))
             return typetok;
     }
 

test/testsymboldatabase.cpp

@@ -363,6 +363,7 @@ private:
         TEST_CASE(symboldatabase99); // #10864
         TEST_CASE(symboldatabase100); // #10174
         TEST_CASE(symboldatabase101);
+        TEST_CASE(symboldatabase102);
 
         TEST_CASE(createSymbolDatabaseFindAllScopes1);
         TEST_CASE(createSymbolDatabaseFindAllScopes2);
@@ -4581,6 +4582,25 @@ private:
             ASSERT(db->scopeList.back().functionList.size() == 1);
             ASSERT(db->scopeList.back().functionList.front().isDefault() == true);
         }
+        {
+            GET_SYMBOL_DB("class C { ~C(); };\n"
+                          "C::~C() = default;");
+            ASSERT(db->scopeList.size() == 2);
+            ASSERT(db->scopeList.back().functionList.size() == 1);
+            ASSERT(db->scopeList.back().functionList.front().isDefault() == true);
+            ASSERT(db->scopeList.back().functionList.front().isDestructor() == true);
+        }
+        {
+            GET_SYMBOL_DB("namespace ns {\n"
+                          "class C { ~C(); };\n"
+                          "}\n"
+                          "using namespace ns;\n"
+                          "C::~C() = default;");
+            ASSERT(db->scopeList.size() == 3);
+            ASSERT(db->scopeList.back().functionList.size() == 1);
+            ASSERT(db->scopeList.back().functionList.front().isDefault() == true);
+            ASSERT(db->scopeList.back().functionList.front().isDestructor() == true);
+        }
     }
 
     void symboldatabase80() { // #9389
@@ -5013,6 +5033,15 @@ private:
         ASSERT(it->tokAt(2)->variable());
     }
 
+    void symboldatabase102() {
+        GET_SYMBOL_DB("std::string f() = delete;\n"
+                      "void g() {}");
+        ASSERT(db);
+        ASSERT(db->scopeList.size() == 2);
+        ASSERT(db->scopeList.front().type == Scope::eGlobal);
+        ASSERT(db->scopeList.back().className == "g");
+    }
+
     void createSymbolDatabaseFindAllScopes1() {
         GET_SYMBOL_DB("void f() { union {int x; char *p;} a={0}; }");
         ASSERT(db->scopeList.size() == 3);

test/testtokenize.cpp

@@ -6321,6 +6321,13 @@ private:
         ASSERT_EQUALS("1f23,(+4+", testAst("1+f(2,3)+4"));
         ASSERT_EQUALS("1f2a&,(+", testAst("1+f(2,&a)"));
         ASSERT_EQUALS("argv[", testAst("int f(char argv[]);"));
+        ASSERT_EQUALS("", testAst("void f();"));
+        ASSERT_EQUALS("", testAst("void f() {}"));
+        ASSERT_EQUALS("", testAst("int f() = delete;"));
+        ASSERT_EQUALS("", testAst("a::b f();"));
+        ASSERT_EQUALS("", testAst("a::b f() {}"));
+        ASSERT_EQUALS("", testAst("a::b f() = delete;"));
+        ASSERT_EQUALS("constdelete=", testAst("int f() const = delete;"));
         ASSERT_EQUALS("", testAst("extern unsigned f(const char *);"));
         ASSERT_EQUALS("charformat*...,", testAst("extern void f(const char *format, ...);"));
         ASSERT_EQUALS("int((void,", testAst("extern int for_each_commit_graft(int (*)(int*), void *);"));