Do not crash when the second parameter of va_start() has no declaration.
[cparser] / parser.c
index 3a3fd39..920fa15 100644 (file)
--- a/parser.c
+++ b/parser.c
@@ -44,14 +44,16 @@ static token_t             lookahead_buffer[MAX_LOOKAHEAD];
 static int                 lookahead_bufpos;
 static stack_entry_t      *environment_stack = NULL;
 static stack_entry_t      *label_stack       = NULL;
-static context_t          *global_context    = NULL;
-static context_t          *context           = NULL;
+static scope_t            *global_scope      = NULL;
+static scope_t            *scope             = NULL;
 static declaration_t      *last_declaration  = NULL;
 static declaration_t      *current_function  = NULL;
 static switch_statement_t *current_switch    = NULL;
 static statement_t        *current_loop      = NULL;
 static goto_statement_t   *goto_first        = NULL;
 static goto_statement_t   *goto_last         = NULL;
+static label_statement_t  *label_first       = NULL;
+static label_statement_t  *label_last        = NULL;
 static struct obstack  temp_obst;
 
 /** The current source position. */
@@ -204,7 +206,8 @@ static size_t get_expression_struct_size(expression_kind_t kind)
                [EXPR_CONDITIONAL]         = sizeof(conditional_expression_t),
                [EXPR_SELECT]              = sizeof(select_expression_t),
                [EXPR_ARRAY_ACCESS]        = sizeof(array_access_expression_t),
-               [EXPR_SIZEOF]              = sizeof(sizeof_expression_t),
+               [EXPR_SIZEOF]              = sizeof(typeprop_expression_t),
+               [EXPR_ALIGNOF]             = sizeof(typeprop_expression_t),
                [EXPR_CLASSIFY_TYPE]       = sizeof(classify_type_expression_t),
                [EXPR_FUNCTION]            = sizeof(string_literal_expression_t),
                [EXPR_PRETTY_FUNCTION]     = sizeof(string_literal_expression_t),
@@ -487,11 +490,11 @@ static void eat_paren(void)
     }                                              \
     next_token();
 
-static void set_context(context_t *new_context)
+static void set_scope(scope_t *new_scope)
 {
-       context = new_context;
+       scope = new_scope;
 
-       last_declaration = new_context->declarations;
+       last_declaration = new_scope->declarations;
        if(last_declaration != NULL) {
                while(last_declaration->next != NULL) {
                        last_declaration = last_declaration->next;
@@ -558,13 +561,13 @@ static void stack_push(stack_entry_t **stack_ptr, declaration_t *declaration)
 static void environment_push(declaration_t *declaration)
 {
        assert(declaration->source_position.input_name != NULL);
-       assert(declaration->parent_context != NULL);
+       assert(declaration->parent_scope != NULL);
        stack_push(&environment_stack, declaration);
 }
 
 static void label_push(declaration_t *declaration)
 {
-       declaration->parent_context = &current_function->context;
+       declaration->parent_scope = &current_function->scope;
        stack_push(&label_stack, declaration);
 }
 
@@ -1102,7 +1105,7 @@ static initializer_t *parse_sub_initializer(type_t *type,
                }
        } else {
                assert(is_type_compound(type));
-               context_t *const context = &type->compound.declaration->context;
+               scope_t *const scope = &type->compound.declaration->scope;
 
                if(token.type == '[') {
                        errorf(HERE,
@@ -1111,7 +1114,7 @@ static initializer_t *parse_sub_initializer(type_t *type,
                        skip_designator();
                }
 
-               declaration_t *first = context->declarations;
+               declaration_t *first = scope->declarations;
                if(first == NULL)
                        return NULL;
                type_t *first_type = first->type;
@@ -1262,7 +1265,7 @@ static declaration_t *parse_compound_type_specifier(bool is_struct)
                        (is_struct ? NAMESPACE_STRUCT : NAMESPACE_UNION);
                declaration->source_position = token.source_position;
                declaration->symbol          = symbol;
-               declaration->parent_context  = context;
+               declaration->parent_scope  = scope;
                if (symbol != NULL) {
                        environment_push(declaration);
                }
@@ -1274,19 +1277,19 @@ static declaration_t *parse_compound_type_specifier(bool is_struct)
                        assert(symbol != NULL);
                        errorf(HERE, "multiple definition of '%s %Y'",
                               is_struct ? "struct" : "union", symbol);
-                       declaration->context.declarations = NULL;
+                       declaration->scope.declarations = NULL;
                }
                declaration->init.is_defined = true;
 
-               int         top          = environment_top();
-               context_t  *last_context = context;
-               set_context(&declaration->context);
+               int       top        = environment_top();
+               scope_t  *last_scope = scope;
+               set_scope(&declaration->scope);
 
                parse_compound_type_entries();
                parse_attributes();
 
-               assert(context == &declaration->context);
-               set_context(last_context);
+               assert(scope == &declaration->scope);
+               set_scope(last_scope);
                environment_pop_to(top);
        }
 
@@ -1360,7 +1363,7 @@ static type_t *parse_enum_specifier(void)
                declaration->namespc         = NAMESPACE_ENUM;
                declaration->source_position = token.source_position;
                declaration->symbol          = symbol;
-               declaration->parent_context  = context;
+               declaration->parent_scope  = scope;
        }
 
        type_t *const type      = allocate_type_zero(TYPE_ENUM);
@@ -2020,7 +2023,7 @@ static construct_type_t *parse_function_declarator(declaration_t *declaration)
 
        declaration_t *parameters = parse_parameters(&type->function);
        if(declaration != NULL) {
-               declaration->context.declarations = parameters;
+               declaration->scope.declarations = parameters;
        }
 
        construct_function_type_t *construct_function_type =
@@ -2243,12 +2246,62 @@ static declaration_t *append_declaration(declaration_t* const declaration)
        if (last_declaration != NULL) {
                last_declaration->next = declaration;
        } else {
-               context->declarations = declaration;
+               scope->declarations = declaration;
        }
        last_declaration = declaration;
        return declaration;
 }
 
+/**
+ * Check if the declaration of main is suspicious.  main should be a
+ * function with external linkage, returning int, taking either zero
+ * arguments, two, or three arguments of appropriate types, ie.
+ *
+ * int main([ int argc, char **argv [, char **env ] ]).
+ *
+ * @param decl    the declaration to check
+ * @param type    the function type of the declaration
+ */
+static void check_type_of_main(const declaration_t *const decl, const function_type_t *const func_type)
+{
+       if (decl->storage_class == STORAGE_CLASS_STATIC) {
+               warningf(decl->source_position, "'main' is normally a non-static function");
+       }
+       if (skip_typeref(func_type->return_type) != type_int) {
+               warningf(decl->source_position, "return type of 'main' should be 'int', but is '%T'", func_type->return_type);
+       }
+       const function_parameter_t *parm = func_type->parameters;
+       if (parm != NULL) {
+               type_t *const first_type = parm->type;
+               if (!types_compatible(skip_typeref(first_type), type_int)) {
+                       warningf(decl->source_position, "first argument of 'main' should be 'int', but is '%T'", first_type);
+               }
+               parm = parm->next;
+               if (parm != NULL) {
+                       type_t *const second_type = parm->type;
+                       if (!types_compatible(skip_typeref(second_type), type_char_ptr_ptr)) {
+                               warningf(decl->source_position, "second argument of 'main' should be 'char**', but is '%T'", second_type);
+                       }
+                       parm = parm->next;
+                       if (parm != NULL) {
+                               type_t *const third_type = parm->type;
+                               if (!types_compatible(skip_typeref(third_type), type_char_ptr_ptr)) {
+                                       warningf(decl->source_position, "third argument of 'main' should be 'char**', but is '%T'", third_type);
+                               }
+                               parm = parm->next;
+                               if (parm != NULL) {
+                                       warningf(decl->source_position, "'main' takes only zero, two or three arguments");
+                               }
+                       }
+               } else {
+                       warningf(decl->source_position, "'main' takes only zero, two or three arguments");
+               }
+       }
+}
+
+/**
+ * Check if a symbol is the equal to "main".
+ */
 static bool is_sym_main(const symbol_t *const sym)
 {
        return strcmp(sym->string, "main") == 0;
@@ -2261,19 +2314,24 @@ static declaration_t *internal_record_declaration(
        const symbol_t *const symbol  = declaration->symbol;
        const namespace_t     namespc = (namespace_t)declaration->namespc;
 
-       const type_t *const type = skip_typeref(declaration->type);
+       type_t       *const orig_type = declaration->type;
+       const type_t *const type      = skip_typeref(orig_type);
        if (is_type_function(type) &&
                        type->function.unspecified_parameters &&
                        warning.strict_prototypes) {
                warningf(declaration->source_position,
                         "function declaration '%#T' is not a prototype",
-                        type, declaration->symbol);
+                        orig_type, declaration->symbol);
+       }
+
+       if (is_function_definition && warning.main && is_sym_main(symbol)) {
+               check_type_of_main(declaration, &type->function);
        }
 
        declaration_t *const previous_declaration = get_declaration(symbol, namespc);
        assert(declaration != previous_declaration);
        if (previous_declaration != NULL) {
-               if (previous_declaration->parent_context == context) {
+               if (previous_declaration->parent_scope == scope) {
                        /* can happen for K&R style declarations */
                        if(previous_declaration->type == NULL) {
                                previous_declaration->type = declaration->type;
@@ -2283,7 +2341,7 @@ static declaration_t *internal_record_declaration(
                        if (!types_compatible(type, prev_type)) {
                                errorf(declaration->source_position,
                                        "declaration '%#T' is incompatible with previous declaration '%#T'",
-                                       type, symbol, previous_declaration->type, symbol);
+                                       orig_type, symbol, previous_declaration->type, symbol);
                                errorf(previous_declaration->source_position, "previous declaration of '%Y' was here", symbol);
                        } else {
                                unsigned old_storage_class = previous_declaration->storage_class;
@@ -2301,7 +2359,7 @@ static declaration_t *internal_record_declaration(
                                                                if (warning.missing_prototypes &&
                                                                    prev_type->function.unspecified_parameters &&
                                                                    !is_sym_main(symbol)) {
-                                                                       warningf(declaration->source_position, "no previous prototype for '%#T'", type, symbol);
+                                                                       warningf(declaration->source_position, "no previous prototype for '%#T'", orig_type, symbol);
                                                                }
                                                        } else if (new_storage_class == STORAGE_CLASS_NONE) {
                                                                new_storage_class = STORAGE_CLASS_EXTERN;
@@ -2343,24 +2401,28 @@ warn_redundant_declaration:
                        }
                        return previous_declaration;
                }
-       } else if (is_function_definition &&
-                       declaration->storage_class != STORAGE_CLASS_STATIC) {
-               if (warning.missing_prototypes && !is_sym_main(symbol)) {
-                       warningf(declaration->source_position, "no previous prototype for '%#T'", type, symbol);
-               } else if (warning.missing_declarations && !is_sym_main(symbol)) {
-                       warningf(declaration->source_position, "no previous declaration for '%#T'", type, symbol);
+       } else if (is_function_definition) {
+               if (declaration->storage_class != STORAGE_CLASS_STATIC) {
+                       if (warning.missing_prototypes && !is_sym_main(symbol)) {
+                               warningf(declaration->source_position, "no previous prototype for '%#T'", orig_type, symbol);
+                       } else if (warning.missing_declarations && !is_sym_main(symbol)) {
+                               warningf(declaration->source_position, "no previous declaration for '%#T'", orig_type, symbol);
+                       }
                }
        } else if (warning.missing_declarations &&
-           declaration->storage_class != STORAGE_CLASS_STATIC &&
-           declaration->storage_class != STORAGE_CLASS_TYPEDEF) {
-               warningf(declaration->source_position, "no previous declaration for '%#T'", type, symbol);
+           scope == global_scope &&
+           !is_type_function(type) && (
+             declaration->storage_class == STORAGE_CLASS_NONE ||
+             declaration->storage_class == STORAGE_CLASS_THREAD
+           )) {
+               warningf(declaration->source_position, "no previous declaration for '%#T'", orig_type, symbol);
        }
 
-       assert(declaration->parent_context == NULL);
+       assert(declaration->parent_scope == NULL);
        assert(declaration->symbol != NULL);
-       assert(context != NULL);
+       assert(scope != NULL);
 
-       declaration->parent_context = context;
+       declaration->parent_scope = scope;
 
        environment_push(declaration);
        return append_declaration(declaration);
@@ -2541,7 +2603,7 @@ static declaration_t *finished_kr_declaration(declaration_t *declaration)
 
        declaration_t *previous_declaration = get_declaration(symbol, namespc);
        if(previous_declaration == NULL ||
-                       previous_declaration->parent_context != context) {
+                       previous_declaration->parent_scope != scope) {
                errorf(HERE, "expected declaration of a function parameter, found '%Y'",
                       symbol);
                return declaration;
@@ -2550,7 +2612,7 @@ static declaration_t *finished_kr_declaration(declaration_t *declaration)
        if(previous_declaration->type == NULL) {
                previous_declaration->type           = declaration->type;
                previous_declaration->storage_class  = declaration->storage_class;
-               previous_declaration->parent_context = context;
+               previous_declaration->parent_scope = scope;
                return previous_declaration;
        } else {
                return record_declaration(declaration);
@@ -2581,14 +2643,14 @@ static void parse_kr_declaration_list(declaration_t *declaration)
                return;
 
        /* push function parameters */
-       int         top          = environment_top();
-       context_t  *last_context = context;
-       set_context(&declaration->context);
+       int       top        = environment_top();
+       scope_t  *last_scope = scope;
+       set_scope(&declaration->scope);
 
-       declaration_t *parameter = declaration->context.declarations;
+       declaration_t *parameter = declaration->scope.declarations;
        for( ; parameter != NULL; parameter = parameter->next) {
-               assert(parameter->parent_context == NULL);
-               parameter->parent_context = context;
+               assert(parameter->parent_scope == NULL);
+               parameter->parent_scope = scope;
                environment_push(parameter);
        }
 
@@ -2598,8 +2660,8 @@ static void parse_kr_declaration_list(declaration_t *declaration)
        }
 
        /* pop function parameters */
-       assert(context == &declaration->context);
-       set_context(last_context);
+       assert(scope == &declaration->scope);
+       set_scope(last_scope);
        environment_pop_to(top);
 
        /* update function type */
@@ -2609,7 +2671,7 @@ static void parse_kr_declaration_list(declaration_t *declaration)
        function_parameter_t *parameters     = NULL;
        function_parameter_t *last_parameter = NULL;
 
-       declaration_t *parameter_declaration = declaration->context.declarations;
+       declaration_t *parameter_declaration = declaration->scope.declarations;
        for( ; parameter_declaration != NULL;
                        parameter_declaration = parameter_declaration->next) {
                type_t *parameter_type = parameter_declaration->type;
@@ -2652,29 +2714,76 @@ static void parse_kr_declaration_list(declaration_t *declaration)
        declaration->type = type;
 }
 
+static bool first_err = true;
+
+/**
+ * When called with first_err set, prints the name of the current function,
+ * else does noting.
+ */
+static void print_in_function(void) {
+       if (first_err) {
+               first_err = false;
+               diagnosticf("%s: In function '%Y':\n",
+                       current_function->source_position.input_name,
+                       current_function->symbol);
+       }
+}
+
 /**
  * Check if all labels are defined in the current function.
+ * Check if all labels are used in the current function.
  */
-static void check_for_missing_labels(void)
+static void check_labels(void)
 {
-       bool first_err = true;
        for (const goto_statement_t *goto_statement = goto_first;
-            goto_statement != NULL;
-            goto_statement = goto_statement->next) {
-                const declaration_t *label = goto_statement->label;
-
-                if (label->source_position.input_name == NULL) {
-                        if (first_err) {
-                                first_err = false;
-                                diagnosticf("%s: In function '%Y':\n",
-                                        current_function->source_position.input_name,
-                                        current_function->symbol);
-                        }
-                        errorf(goto_statement->statement.source_position,
-                                "label '%Y' used but not defined", label->symbol);
+           goto_statement != NULL;
+           goto_statement = goto_statement->next) {
+               declaration_t *label = goto_statement->label;
+
+               label->used = true;
+               if (label->source_position.input_name == NULL) {
+                       print_in_function();
+                       errorf(goto_statement->statement.source_position,
+                               "label '%Y' used but not defined", label->symbol);
                 }
        }
        goto_first = goto_last = NULL;
+
+       if (warning.unused_label) {
+               for (const label_statement_t *label_statement = label_first;
+                        label_statement != NULL;
+                        label_statement = label_statement->next) {
+                       const declaration_t *label = label_statement->label;
+
+                       if (! label->used) {
+                               print_in_function();
+                               warningf(label_statement->statement.source_position,
+                                       "label '%Y' defined but not used", label->symbol);
+                       }
+               }
+       }
+       label_first = label_last = NULL;
+}
+
+/**
+ * Check declarations of current_function for unused entities.
+ */
+static void check_declarations(void)
+{
+       if (warning.unused_parameter) {
+               const scope_t *scope = &current_function->scope;
+
+               const declaration_t *parameter = scope->declarations;
+               for (; parameter != NULL; parameter = parameter->next) {
+                       if (! parameter->used) {
+                               print_in_function();
+                               warningf(parameter->source_position,
+                                       "unused parameter '%Y'", parameter->symbol);
+                       }
+               }
+       }
+       if (warning.unused_variable) {
+       }
 }
 
 static void parse_external_declaration(void)
@@ -2737,23 +2846,23 @@ static void parse_external_declaration(void)
 
        declaration_t *const declaration = record_function_definition(ndeclaration);
        if(ndeclaration != declaration) {
-               declaration->context = ndeclaration->context;
+               declaration->scope = ndeclaration->scope;
        }
        type = skip_typeref(declaration->type);
 
-       /* push function parameters and switch context */
-       int         top          = environment_top();
-       context_t  *last_context = context;
-       set_context(&declaration->context);
+       /* push function parameters and switch scope */
+       int       top        = environment_top();
+       scope_t  *last_scope = scope;
+       set_scope(&declaration->scope);
 
-       declaration_t *parameter = declaration->context.declarations;
+       declaration_t *parameter = declaration->scope.declarations;
        for( ; parameter != NULL; parameter = parameter->next) {
-               if(parameter->parent_context == &ndeclaration->context) {
-                       parameter->parent_context = context;
+               if(parameter->parent_scope == &ndeclaration->scope) {
+                       parameter->parent_scope = scope;
                }
-               assert(parameter->parent_context == NULL
-                               || parameter->parent_context == context);
-               parameter->parent_context = context;
+               assert(parameter->parent_scope == NULL
+                               || parameter->parent_scope == scope);
+               parameter->parent_scope = scope;
                environment_push(parameter);
        }
 
@@ -2768,7 +2877,9 @@ static void parse_external_declaration(void)
                current_function                    = declaration;
 
                declaration->init.statement = parse_compound_statement();
-               check_for_missing_labels();
+               first_err = true;
+               check_labels();
+               check_declarations();
 
                assert(current_function == declaration);
                current_function = old_current_function;
@@ -2776,8 +2887,8 @@ static void parse_external_declaration(void)
        }
 
 end_of_parse_external_declaration:
-       assert(context == &declaration->context);
-       set_context(last_context);
+       assert(scope == &declaration->scope);
+       set_scope(last_scope);
        environment_pop_to(top);
 }
 
@@ -2974,18 +3085,18 @@ static declaration_t *create_implicit_function(symbol_t *symbol,
        declaration->type            = type;
        declaration->symbol          = symbol;
        declaration->source_position = source_position;
-       declaration->parent_context  = global_context;
+       declaration->parent_scope  = global_scope;
 
-       context_t *old_context = context;
-       set_context(global_context);
+       scope_t *old_scope = scope;
+       set_scope(global_scope);
 
        environment_push(declaration);
-       /* prepend the declaration to the global declarations list */
-       declaration->next     = context->declarations;
-       context->declarations = declaration;
+       /* prepends the declaration to the global declarations list */
+       declaration->next   = scope->declarations;
+       scope->declarations = declaration;
 
-       assert(context == global_context);
-       set_context(old_context);
+       assert(scope == global_scope);
+       set_scope(old_scope);
 
        return declaration;
 }
@@ -3134,6 +3245,9 @@ static expression_t *parse_reference(void)
        ref->declaration         = declaration;
        ref->expression.datatype = type;
 
+       /* this declaration is used */
+       declaration->used = true;
+
        return expression;
 }
 
@@ -3330,7 +3444,9 @@ static expression_t *parse_va_start(void)
        expression_t *const expr = parse_assignment_expression();
        if (expr->kind == EXPR_REFERENCE) {
                declaration_t *const decl = expr->reference.declaration;
-               if (decl->parent_context == &current_function->context &&
+               if (decl == NULL)
+                       return create_invalid_expression();
+               if (decl->parent_scope == &current_function->scope &&
                    decl->next == NULL) {
                        expression->va_starte.parameter = decl;
                        expect(')');
@@ -3436,6 +3552,7 @@ static expression_t *parse_compare_builtin(void)
                panic("invalid compare builtin found");
                break;
        }
+       expression->base.source_position = HERE;
        next_token();
 
        expect('(');
@@ -3449,10 +3566,10 @@ static expression_t *parse_compare_builtin(void)
 
        type_t *const type_left  = skip_typeref(orig_type_left);
        type_t *const type_right = skip_typeref(orig_type_right);
-       if(!is_type_floating(type_left) && !is_type_floating(type_right)) {
+       if(!is_type_float(type_left) && !is_type_float(type_right)) {
                if (is_type_valid(type_left) && is_type_valid(type_right)) {
                        type_error_incompatible("invalid operands in comparison",
-                               token.source_position, orig_type_left, orig_type_right);
+                               expression->base.source_position, orig_type_left, orig_type_right);
                }
        } else {
                semantic_comparison(&expression->binary);
@@ -3493,20 +3610,6 @@ static expression_t *parse_assume(void) {
        return expression;
 }
 
-static expression_t *parse_alignof(void) {
-       eat(T___alignof__);
-
-       expression_t *expression
-               = allocate_expression_zero(EXPR_ALIGNOF);
-
-       expect('(');
-       expression->alignofe.type = parse_typename();
-       expect(')');
-
-       expression->base.datatype = type_size_t;
-       return expression;
-}
-
 static expression_t *parse_primary_expression(void)
 {
        switch(token.type) {
@@ -3548,8 +3651,6 @@ static expression_t *parse_primary_expression(void)
                return parse_builtin_constant();
        case T___builtin_prefetch:
                return parse_builtin_prefetch();
-       case T___alignof__:
-               return parse_alignof();
        case T_assume:
                return parse_assume();
 
@@ -3631,28 +3732,37 @@ static expression_t *parse_array_expression(unsigned precedence,
        return (expression_t*) array_access;
 }
 
-static expression_t *parse_sizeof(unsigned precedence)
+static expression_t *parse_typeprop(expression_kind_t kind, unsigned precedence)
 {
-       eat(T_sizeof);
-
-       sizeof_expression_t *sizeof_expression
-               = allocate_ast_zero(sizeof(sizeof_expression[0]));
-       sizeof_expression->expression.kind     = EXPR_SIZEOF;
-       sizeof_expression->expression.datatype = type_size_t;
+       expression_t *tp_expression
+               = allocate_expression_zero(kind);
+       tp_expression->base.datatype = type_size_t;
 
        if(token.type == '(' && is_declaration_specifier(look_ahead(1), true)) {
                next_token();
-               sizeof_expression->type = parse_typename();
+               tp_expression->typeprop.type = parse_typename();
                expect(')');
        } else {
                expression_t *expression  = parse_sub_expression(precedence);
                expression->base.datatype = revert_automatic_type_conversion(expression);
 
-               sizeof_expression->type            = expression->base.datatype;
-               sizeof_expression->size_expression = expression;
+               tp_expression->typeprop.type          = expression->base.datatype;
+               tp_expression->typeprop.tp_expression = expression;
        }
 
-       return (expression_t*) sizeof_expression;
+       return tp_expression;
+}
+
+static expression_t *parse_sizeof(unsigned precedence)
+{
+       eat(T_sizeof);
+       return parse_typeprop(EXPR_SIZEOF, precedence);
+}
+
+static expression_t *parse_alignof(unsigned precedence)
+{
+       eat(T___alignof__);
+       return parse_typeprop(EXPR_SIZEOF, precedence);
 }
 
 static expression_t *parse_select_expression(unsigned precedence,
@@ -3707,7 +3817,7 @@ static expression_t *parse_select_expression(unsigned precedence,
                return create_invalid_expression();
        }
 
-       declaration_t *iter = declaration->context.declarations;
+       declaration_t *iter = declaration->scope.declarations;
        for( ; iter != NULL; iter = iter->next) {
                if(iter->symbol == symbol) {
                        break;
@@ -3798,7 +3908,7 @@ static expression_t *parse_call_expression(unsigned precedence,
                for( ; parameter != NULL && argument != NULL;
                                parameter = parameter->next, argument = argument->next) {
                        type_t *expected_type = parameter->type;
-                       /* TODO report context in error messages */
+                       /* TODO report scope in error messages */
                        expression_t *const arg_expr = argument->expression;
                        type_t       *const res_type = semantic_assign(expected_type, arg_expr, "function call");
                        if (res_type == NULL) {
@@ -4253,6 +4363,11 @@ static void semantic_sub(binary_expression_t *expression)
        }
 }
 
+/**
+ * Check the semantics of comparison expressions.
+ *
+ * @param expression   The expression to check.
+ */
 static void semantic_comparison(binary_expression_t *expression)
 {
        expression_t *left            = expression->left;
@@ -4265,10 +4380,24 @@ static void semantic_comparison(binary_expression_t *expression)
 
        /* TODO non-arithmetic types */
        if(is_type_arithmetic(type_left) && is_type_arithmetic(type_right)) {
+               if (warning.sign_compare &&
+                   (expression->expression.kind != EXPR_BINARY_EQUAL &&
+                    expression->expression.kind != EXPR_BINARY_NOTEQUAL) &&
+                   (is_type_signed(type_left) != is_type_signed(type_right))) {
+                       warningf(expression->expression.source_position,
+                               "comparison between signed and unsigned");
+               }
                type_t *arithmetic_type = semantic_arithmetic(type_left, type_right);
                expression->left  = create_implicit_cast(left, arithmetic_type);
                expression->right = create_implicit_cast(right, arithmetic_type);
                expression->expression.datatype = arithmetic_type;
+               if (warning.float_equal &&
+                   (expression->expression.kind == EXPR_BINARY_EQUAL ||
+                    expression->expression.kind == EXPR_BINARY_NOTEQUAL) &&
+                   is_type_float(arithmetic_type)) {
+                       warningf(expression->expression.source_position,
+                                "comparing floating point with == or != is unsafe");
+               }
        } else if (is_type_pointer(type_left) && is_type_pointer(type_right)) {
                /* TODO check compatibility */
        } else if (is_type_pointer(type_left)) {
@@ -4277,7 +4406,8 @@ static void semantic_comparison(binary_expression_t *expression)
                expression->left = create_implicit_cast(left, type_right);
        } else if (is_type_valid(type_left) && is_type_valid(type_right)) {
                type_error_incompatible("invalid operands in comparison",
-                                       token.source_position, type_left, type_right);
+                                       expression->expression.source_position,
+                                       type_left, type_right);
        }
        expression->expression.datatype = type_int;
 }
@@ -4361,8 +4491,8 @@ static void semantic_logical_op(binary_expression_t *expression)
  */
 static bool has_const_fields(const compound_type_t *type)
 {
-       const context_t     *context = &type->declaration->context;
-       const declaration_t *declaration = context->declarations;
+       const scope_t       *scope       = &type->declaration->scope;
+       const declaration_t *declaration = scope->declarations;
 
        for (; declaration != NULL; declaration = declaration->next) {
                if (declaration->namespc != NAMESPACE_NORMAL)
@@ -4539,10 +4669,12 @@ static expression_t *parse_##binexpression_type(unsigned precedence,      \
                                                 expression_t *left)       \
 {                                                                         \
        eat(token_type);                                                      \
+       source_position_t pos = HERE;                                         \
                                                                           \
        expression_t *right = parse_sub_expression(precedence + lr);          \
                                                                           \
        expression_t *binexpr = allocate_expression_zero(binexpression_type); \
+       binexpr->base.source_position = pos;                                  \
        binexpr->binary.left  = left;                                         \
        binexpr->binary.right = right;                                        \
        sfunc(&binexpr->binary);                                              \
@@ -4758,7 +4890,8 @@ static void init_expression_parsers(void)
                                                                  T_PLUSPLUS,   25);
        register_expression_parser(parse_EXPR_UNARY_PREFIX_DECREMENT,
                                                                  T_MINUSMINUS, 25);
-       register_expression_parser(parse_sizeof,                  T_sizeof,     25);
+       register_expression_parser(parse_sizeof,                      T_sizeof, 25);
+       register_expression_parser(parse_alignof,                T___alignof__, 25);
        register_expression_parser(parse_extension,            T___extension__, 25);
        register_expression_parser(parse_builtin_classify_type,
                                                     T___builtin_classify_type, 25);
@@ -4975,7 +5108,7 @@ static declaration_t *get_label(symbol_t *symbol)
        /* if we found a label in the same function, then we already created the
         * declaration */
        if(candidate != NULL
-                       && candidate->parent_context == &current_function->context) {
+                       && candidate->parent_scope == &current_function->scope) {
                return candidate;
        }
 
@@ -5023,9 +5156,24 @@ static statement_t *parse_label_statement(void)
                errorf(HERE, "label at end of compound statement");
                return (statement_t*) label_statement;
        } else {
-               label_statement->label_statement = parse_statement();
+               if (token.type == ';') {
+                       /* eat an empty statement here, to avoid the warning about an empty
+                        * after a label.  label:; is commonly used to have a label before
+                        * a }. */
+                       next_token();
+               } else {
+                       label_statement->label_statement = parse_statement();
+               }
        }
 
+       /* remember the labels's in a list for later checking */
+       if (label_last == NULL) {
+               label_first = label_statement;
+       } else {
+               label_last->next = label_statement;
+       }
+       label_last = label_statement;
+
        return (statement_t*) label_statement;
 }
 
@@ -5151,9 +5299,9 @@ static statement_t *parse_for(void)
 
        expect('(');
 
-       int         top          = environment_top();
-       context_t  *last_context = context;
-       set_context(&statement->context);
+       int      top        = environment_top();
+       scope_t *last_scope = scope;
+       set_scope(&statement->scope);
 
        if(token.type != ';') {
                if(is_declaration_specifier(&token, false)) {
@@ -5176,8 +5324,8 @@ static statement_t *parse_for(void)
        expect(')');
        statement->body = parse_loop_body((statement_t*)statement);
 
-       assert(context == &statement->context);
-       set_context(last_context);
+       assert(scope == &statement->scope);
+       set_scope(last_scope);
        environment_pop_to(top);
 
        return (statement_t*) statement;
@@ -5209,10 +5357,11 @@ static statement_t *parse_goto(void)
 
        /* remember the goto's in a list for later checking */
        if (goto_last == NULL) {
-               goto_first = goto_last = statement;
+               goto_first = statement;
        } else {
                goto_last->next = statement;
        }
+       goto_last = statement;
 
        expect(';');
 
@@ -5281,6 +5430,31 @@ static bool is_local_var_declaration(const declaration_t *declaration) {
        }
 }
 
+/**
+ * Check if a given declaration represents a variable.
+ */
+static bool is_var_declaration(const declaration_t *declaration) {
+       switch ((storage_class_tag_t) declaration->storage_class) {
+       case STORAGE_CLASS_NONE:
+       case STORAGE_CLASS_EXTERN:
+       case STORAGE_CLASS_STATIC:
+       case STORAGE_CLASS_AUTO:
+       case STORAGE_CLASS_REGISTER:
+       case STORAGE_CLASS_THREAD:
+       case STORAGE_CLASS_THREAD_EXTERN:
+       case STORAGE_CLASS_THREAD_STATIC: {
+               const type_t *type = skip_typeref(declaration->type);
+               if(is_type_function(type)) {
+                       return false;
+               } else {
+                       return true;
+               }
+       }
+       default:
+               return false;
+       }
+}
+
 /**
  * Check if a given expression represents a local variable.
  */
@@ -5293,6 +5467,21 @@ static bool is_local_variable(const expression_t *expression)
        return is_local_var_declaration(declaration);
 }
 
+/**
+ * Check if a given expression represents a local variable and
+ * return its declaration then, else return NULL.
+ */
+declaration_t *expr_is_variable(const expression_t *expression)
+{
+       if (expression->base.kind != EXPR_REFERENCE) {
+               return NULL;
+       }
+       declaration_t *declaration = expression->reference.declaration;
+       if (is_var_declaration(declaration))
+               return declaration;
+       return NULL;
+}
+
 /**
  * Parse a return statement.
  */
@@ -5366,7 +5555,7 @@ static statement_t *parse_declaration_statement(void)
        parse_declaration(record_declaration);
 
        if(before == NULL) {
-               statement->declaration.declarations_begin = context->declarations;
+               statement->declaration.declarations_begin = scope->declarations;
        } else {
                statement->declaration.declarations_begin = before->next;
        }
@@ -5514,9 +5703,9 @@ static statement_t *parse_compound_statement(void)
 
        eat('{');
 
-       int        top          = environment_top();
-       context_t *last_context = context;
-       set_context(&compound_statement->context);
+       int      top        = environment_top();
+       scope_t *last_scope = scope;
+       set_scope(&compound_statement->scope);
 
        statement_t *last_statement = NULL;
 
@@ -5543,8 +5732,8 @@ static statement_t *parse_compound_statement(void)
                errorf(compound_statement->statement.source_position, "end of file while looking for closing '}'");
        }
 
-       assert(context == &compound_statement->context);
-       set_context(last_context);
+       assert(scope == &compound_statement->scope);
+       set_scope(last_scope);
        environment_pop_to(top);
 
        return (statement_t*) compound_statement;
@@ -5570,6 +5759,37 @@ static void initialize_builtin_types(void)
        type_wchar_t_ptr   = make_pointer_type(type_wchar_t,   TYPE_QUALIFIER_NONE);
 }
 
+/**
+ * Check for unused global static functions and variables
+ */
+static void check_unused_globals(void)
+{
+       if (!warning.unused_function && !warning.unused_variable)
+               return;
+
+       for (const declaration_t *decl = global_scope->declarations; decl != NULL; decl = decl->next) {
+               if (decl->used || decl->storage_class != STORAGE_CLASS_STATIC)
+                       continue;
+
+               type_t *const type = decl->type;
+               const char *s;
+               if (is_type_function(skip_typeref(type))) {
+                       if (!warning.unused_function || decl->is_inline)
+                               continue;
+
+                       s = (decl->init.statement != NULL ? "defined" : "declared");
+               } else {
+                       if (!warning.unused_variable)
+                               continue;
+
+                       s = "defined";
+               }
+
+               warningf(decl->source_position, "'%#T' %s but not used",
+                       type, decl->symbol, s);
+       }
+}
+
 /**
  * Parse a translation unit.
  */
@@ -5577,11 +5797,11 @@ static translation_unit_t *parse_translation_unit(void)
 {
        translation_unit_t *unit = allocate_ast_zero(sizeof(unit[0]));
 
-       assert(global_context == NULL);
-       global_context = &unit->context;
+       assert(global_scope == NULL);
+       global_scope = &unit->scope;
 
-       assert(context == NULL);
-       set_context(&unit->context);
+       assert(scope == NULL);
+       set_scope(&unit->scope);
 
        initialize_builtin_types();
 
@@ -5595,12 +5815,13 @@ static translation_unit_t *parse_translation_unit(void)
                }
        }
 
-       assert(context == &unit->context);
-       context          = NULL;
+       assert(scope == &unit->scope);
+       scope          = NULL;
        last_declaration = NULL;
 
-       assert(global_context == &unit->context);
-       global_context = NULL;
+       assert(global_scope == &unit->scope);
+       check_unused_globals();
+       global_scope = NULL;
 
        return unit;
 }