Fix 10588: crash (#3691)

lib/symboldatabase.cpp

@@ -1704,6 +1704,11 @@ bool SymbolDatabase::isFunction(const Token *tok, const Scope* outerScope, const
             while (Token::Match(tok1, "%type%|*|&") && !endsWith(tok1->str(), ':') && (!isReservedName(tok1->str()) || tok1->str() == "const"))
                 tok1 = tok1->previous();
 
+            // skip over decltype
+            if (Token::simpleMatch(tok1, ")") && tok1->link() &&
+                Token::simpleMatch(tok1->link()->previous(), "decltype ("))
+                tok1 = tok1->link()->tokAt(-2);
+
             // skip over template
             if (tok1 && tok1->str() == ">") {
                 if (tok1->link())
@@ -1730,6 +1735,9 @@ bool SymbolDatabase::isFunction(const Token *tok, const Scope* outerScope, const
                     tok1 = tok1->previous();
                 else if (tok1 && tok1->str() == ">" && tok1->link() && Token::Match(tok1->link()->previous(), "%name%"))
                     tok1 = tok1->link()->tokAt(-2);
+                else if (Token::simpleMatch(tok1, ")") && tok1->link() &&
+                         Token::simpleMatch(tok1->link()->previous(), "decltype ("))
+                    tok1 = tok1->link()->tokAt(-2);
             }
 
             // skip over modifiers and other stuff
@@ -2348,6 +2356,11 @@ const Token *Function::setFlags(const Token *tok1, const Scope *scope)
             isConstexpr(true);
         }
 
+        // decltype
+        else if (tok1->str() == ")" && Token::simpleMatch(tok1->link()->previous(), "decltype (")) {
+            tok1 = tok1->link()->previous();
+        }
+
         // Function template
         else if (tok1->link() && tok1->str() == ">" && Token::simpleMatch(tok1->link()->previous(), "template <")) {
             templateDef = tok1->link()->previous();

test/testsymboldatabase.cpp

@@ -192,6 +192,7 @@ private:
         TEST_CASE(hasMissingInlineClassFunction);
         TEST_CASE(hasClassFunction);
         TEST_CASE(hasClassFunction_trailingReturnType);
+        TEST_CASE(hasClassFunction_decltype_auto);
 
         TEST_CASE(hasRegularFunctionReturningFunctionPointer);
         TEST_CASE(hasInlineClassFunctionReturningFunctionPointer);
@@ -1629,6 +1630,28 @@ private:
         ASSERT(function && function->functionScope == scope && scope->function == function && function->nestedIn == db->findScopeByName("Fred"));
     }
 
+    void hasClassFunction_decltype_auto()
+    {
+        GET_SYMBOL_DB("struct d { decltype(auto) f() {} };");
+
+        // 3 scopes: Global, Class, and Function
+        ASSERT(db && db->scopeList.size() == 3);
+
+        const Token* const functionToken = Token::findsimplematch(tokenizer.tokens(), "f");
+
+        const Scope* scope = findFunctionScopeByToken(db, functionToken);
+
+        ASSERT(scope && scope->className == "f");
+
+        ASSERT(scope->functionOf && scope->functionOf == db->findScopeByName("d"));
+
+        const Function* function = findFunctionByName("f", &db->scopeList.back());
+
+        ASSERT(function && function->token->str() == "f");
+        ASSERT(function && function->token == functionToken);
+        ASSERT(function && function->hasBody());
+    }
+
     void hasRegularFunctionReturningFunctionPointer() {
         GET_SYMBOL_DB("void (*func(int f))(char) { }");
 

test/testvalueflow.cpp

@@ -6185,6 +6185,18 @@ private:
                "    } while (last > 0);\n"
                "}\n";
         valueOfTok(code, "last");
+
+        code = "struct a {\n"
+               "  void clear();\n"
+               "  int b();\n"
+               "};\n"
+               "struct d {\n"
+               "  void c(int);\n"
+               "  decltype(auto) f() { c(0 != e.b()); }\n"
+               "  a e;\n"
+               "};\n"
+               "void d::c(int) { e.clear(); }\n";
+        valueOfTok(code, "e");
     }
 
     void valueFlowHang() {