2017-05-16 Nathan Sidwell <nathan@acm.org>
* name-lookup.c (check_local_shadow): New, broke out of ...
(pushdecl_maybe_friend_1): ... here. Call it.
===================================================================
@@ -1184,6 +1184,215 @@ supplement_binding (cxx_binding *binding
return ret;
}
+/* DECL is being declared at a local scope. Emit suitable shadow
+ warnings. */
+
+static void
+check_local_shadow (tree decl)
+{
+ /* Don't complain about the parms we push and then pop
+ while tentatively parsing a function declarator. */
+ if (TREE_CODE (decl) == PARM_DECL && !DECL_CONTEXT (decl))
+ return;
+
+ /* Inline decls shadow nothing. */
+ if (DECL_FROM_INLINE (decl))
+ return;
+
+ /* External decls are something else. */
+ if (DECL_EXTERNAL (decl))
+ return;
+
+ tree old = NULL_TREE;
+ cp_binding_level *old_scope = NULL;
+ if (cxx_binding *binding = outer_binding (DECL_NAME (decl), NULL, true))
+ {
+ old = binding->value;
+ old_scope = binding->scope;
+ }
+ while (old && VAR_P (old) && DECL_DEAD_FOR_LOCAL (old))
+ old = DECL_SHADOWED_FOR_VAR (old);
+
+ tree shadowed = NULL_TREE;
+ if (old
+ && (TREE_CODE (old) == PARM_DECL
+ || VAR_P (old)
+ || (TREE_CODE (old) == TYPE_DECL
+ && (!DECL_ARTIFICIAL (old)
+ || TREE_CODE (decl) == TYPE_DECL)))
+ && (!DECL_ARTIFICIAL (decl)
+ || DECL_IMPLICIT_TYPEDEF_P (decl)
+ || (VAR_P (decl) && DECL_ANON_UNION_VAR_P (decl))))
+ {
+ /* DECL shadows a local thing possibly of interest. */
+
+ /* Don't complain if it's from an enclosing function. */
+ if (DECL_CONTEXT (old) == current_function_decl
+ && TREE_CODE (decl) != PARM_DECL
+ && TREE_CODE (old) == PARM_DECL)
+ {
+ /* Go to where the parms should be and see if we find
+ them there. */
+ cp_binding_level *b = current_binding_level->level_chain;
+
+ if (FUNCTION_NEEDS_BODY_BLOCK (current_function_decl))
+ /* Skip the ctor/dtor cleanup level. */
+ b = b->level_chain;
+
+ /* ARM $8.3 */
+ if (b->kind == sk_function_parms)
+ {
+ error ("declaration of %q#D shadows a parameter", decl);
+ return;
+ }
+ }
+
+ /* The local structure or class can't use parameters of
+ the containing function anyway. */
+ if (DECL_CONTEXT (old) != current_function_decl)
+ {
+ for (cp_binding_level *scope = current_binding_level;
+ scope != old_scope; scope = scope->level_chain)
+ if (scope->kind == sk_class
+ && !LAMBDA_TYPE_P (scope->this_entity))
+ return;
+ }
+ /* Error if redeclaring a local declared in a
+ init-statement or in the condition of an if or
+ switch statement when the new declaration is in the
+ outermost block of the controlled statement.
+ Redeclaring a variable from a for or while condition is
+ detected elsewhere. */
+ else if (VAR_P (old)
+ && old_scope == current_binding_level->level_chain
+ && (old_scope->kind == sk_cond || old_scope->kind == sk_for))
+ {
+ error ("redeclaration of %q#D", decl);
+ inform (DECL_SOURCE_LOCATION (old),
+ "%q#D previously declared here", old);
+ return;
+ }
+ /* C++11:
+ 3.3.3/3: The name declared in an exception-declaration (...)
+ shall not be redeclared in the outermost block of the handler.
+ 3.3.3/2: A parameter name shall not be redeclared (...) in
+ the outermost block of any handler associated with a
+ function-try-block.
+ 3.4.1/15: The function parameter names shall not be redeclared
+ in the exception-declaration nor in the outermost block of a
+ handler for the function-try-block. */
+ else if ((TREE_CODE (old) == VAR_DECL
+ && old_scope == current_binding_level->level_chain
+ && old_scope->kind == sk_catch)
+ || (TREE_CODE (old) == PARM_DECL
+ && (current_binding_level->kind == sk_catch
+ || current_binding_level->level_chain->kind == sk_catch)
+ && in_function_try_handler))
+ {
+ if (permerror (input_location, "redeclaration of %q#D", decl))
+ inform (DECL_SOURCE_LOCATION (old),
+ "%q#D previously declared here", old);
+ return;
+ }
+
+ /* If '-Wshadow=compatible-local' is specified without other
+ -Wshadow= flags, we will warn only when the type of the
+ shadowing variable (DECL) can be converted to that of the
+ shadowed parameter (OLD_LOCAL). The reason why we only check
+ if DECL's type can be converted to OLD_LOCAL's type (but not the
+ other way around) is because when users accidentally shadow a
+ parameter, more than often they would use the variable
+ thinking (mistakenly) it's still the parameter. It would be
+ rare that users would use the variable in the place that
+ expects the parameter but thinking it's a new decl. */
+
+ enum opt_code warning_code;
+ if (warn_shadow)
+ warning_code = OPT_Wshadow;
+ else if (warn_shadow_local)
+ warning_code = OPT_Wshadow_local;
+ else if (warn_shadow_compatible_local
+ && can_convert (TREE_TYPE (old), TREE_TYPE (decl), tf_none))
+ warning_code = OPT_Wshadow_compatible_local;
+ else
+ return;
+
+ const char *msg;
+ if (TREE_CODE (old) == PARM_DECL)
+ msg = "declaration of %q#D shadows a parameter";
+ else if (is_capture_proxy (old))
+ msg = "declaration of %qD shadows a lambda capture";
+ else
+ msg = "declaration of %qD shadows a previous local";
+
+ if (warning_at (input_location, warning_code, msg, decl))
+ {
+ shadowed = old;
+ goto inform_shadowed;
+ }
+ return;
+ }
+
+ if (!warn_shadow)
+ return;
+
+ /* Don't warn for artificial things that are not implicit typedefs. */
+ if (DECL_ARTIFICIAL (decl) && !DECL_IMPLICIT_TYPEDEF_P (decl))
+ return;
+
+ if (nonlambda_method_basetype ())
+ if (tree member = lookup_member (current_nonlambda_class_type (),
+ DECL_NAME (decl), /*protect=*/0,
+ /*want_type=*/false, tf_warning_or_error))
+ {
+ member = MAYBE_BASELINK_FUNCTIONS (member);
+
+ /* Warn if a variable shadows a non-function, or the variable
+ is a function or a pointer-to-function. */
+ if ((TREE_CODE (member) != FUNCTION_DECL
+ && TREE_CODE (member) != OVERLOAD)
+ || TREE_CODE (decl) == FUNCTION_DECL
+ || TYPE_PTRFN_P (TREE_TYPE (decl))
+ || TYPE_PTRMEMFUNC_P (TREE_TYPE (decl)))
+ {
+ if (warning_at (input_location, OPT_Wshadow,
+ "declaration of %qD shadows a member of %qT",
+ decl, current_nonlambda_class_type ())
+ && DECL_P (member))
+ {
+ shadowed = member;
+ goto inform_shadowed;
+ }
+ }
+ return;
+ }
+
+ /* Now look for a namespace shadow. */
+ old = get_namespace_binding (current_namespace, DECL_NAME (decl));
+ if (old
+ && (VAR_P (old)
+ || (TREE_CODE (old) == TYPE_DECL
+ && (!DECL_ARTIFICIAL (old)
+ || TREE_CODE (decl) == TYPE_DECL)))
+ && !instantiating_current_function_p ())
+ /* XXX shadow warnings in outer-more namespaces */
+ {
+ if (warning_at (input_location, OPT_Wshadow,
+ "declaration of %qD shadows a global declaration",
+ decl))
+ {
+ shadowed = old;
+ goto inform_shadowed;
+ }
+ return;
+ }
+
+ return;
+
+ inform_shadowed:
+ inform (DECL_SOURCE_LOCATION (shadowed), "shadowed declaration is here");
+}
+
/* Record a decl-node X as belonging to the current lexical scope.
Check for errors (such as an incompatible declaration for the same
name already seen in the same scope). IS_FRIEND is true if X is
@@ -1570,13 +1779,11 @@ pushdecl_maybe_friend_1 (tree x, bool is
/* Here to install a non-global value. */
tree oldglobal = get_namespace_binding (current_namespace, name);
tree oldlocal = NULL_TREE;
- cp_binding_level *oldscope = NULL;
cxx_binding *oldbinding = outer_binding (name, NULL, true);
if (oldbinding)
- {
- oldlocal = oldbinding->value;
- oldscope = oldbinding->scope;
- }
+ oldlocal = oldbinding->value;
+
+ check_local_shadow (x);
if (need_new_binding)
{
@@ -1637,216 +1844,6 @@ pushdecl_maybe_friend_1 (tree x, bool is
&& DECL_EXTERNAL (x)
&& TREE_PUBLIC (x))
TREE_PUBLIC (name) = 1;
-
- /* Don't complain about the parms we push and then pop
- while tentatively parsing a function declarator. */
- if (TREE_CODE (x) == PARM_DECL && DECL_CONTEXT (x) == NULL_TREE)
- /* Ignore. */;
-
- /* Warn if shadowing an argument at the top level of the body. */
- else if (oldlocal != NULL_TREE && !DECL_EXTERNAL (x)
- /* Inline decls shadow nothing. */
- && !DECL_FROM_INLINE (x)
- && (TREE_CODE (oldlocal) == PARM_DECL
- || VAR_P (oldlocal)
- /* If the old decl is a type decl, only warn if the
- old decl is an explicit typedef or if both the old
- and new decls are type decls. */
- || (TREE_CODE (oldlocal) == TYPE_DECL
- && (!DECL_ARTIFICIAL (oldlocal)
- || TREE_CODE (x) == TYPE_DECL)))
- /* Don't check for internally generated vars unless
- it's an implicit typedef (see create_implicit_typedef
- in decl.c) or anonymous union variable. */
- && (!DECL_ARTIFICIAL (x)
- || DECL_IMPLICIT_TYPEDEF_P (x)
- || (VAR_P (x) && DECL_ANON_UNION_VAR_P (x))))
- {
- bool nowarn = false;
-
- /* Don't complain if it's from an enclosing function. */
- if (DECL_CONTEXT (oldlocal) == current_function_decl
- && TREE_CODE (x) != PARM_DECL
- && TREE_CODE (oldlocal) == PARM_DECL)
- {
- /* Go to where the parms should be and see if we find
- them there. */
- cp_binding_level *b = current_binding_level->level_chain;
-
- if (FUNCTION_NEEDS_BODY_BLOCK (current_function_decl))
- /* Skip the ctor/dtor cleanup level. */
- b = b->level_chain;
-
- /* ARM $8.3 */
- if (b->kind == sk_function_parms)
- {
- error ("declaration of %q#D shadows a parameter", x);
- nowarn = true;
- }
- }
-
- /* The local structure or class can't use parameters of
- the containing function anyway. */
- if (DECL_CONTEXT (oldlocal) != current_function_decl)
- {
- cp_binding_level *scope = current_binding_level;
- tree context = DECL_CONTEXT (oldlocal);
- for (; scope; scope = scope->level_chain)
- {
- if (scope->kind == sk_function_parms
- && scope->this_entity == context)
- break;
- if (scope->kind == sk_class
- && !LAMBDA_TYPE_P (scope->this_entity))
- {
- nowarn = true;
- break;
- }
- }
- }
- /* Error if redeclaring a local declared in a
- init-statement or in the condition of an if or
- switch statement when the new declaration is in the
- outermost block of the controlled statement.
- Redeclaring a variable from a for or while condition is
- detected elsewhere. */
- else if (VAR_P (oldlocal)
- && oldscope == current_binding_level->level_chain
- && (oldscope->kind == sk_cond
- || oldscope->kind == sk_for))
- {
- error ("redeclaration of %q#D", x);
- inform (DECL_SOURCE_LOCATION (oldlocal),
- "%q#D previously declared here", oldlocal);
- nowarn = true;
- }
- /* C++11:
- 3.3.3/3: The name declared in an exception-declaration (...)
- shall not be redeclared in the outermost block of the handler.
- 3.3.3/2: A parameter name shall not be redeclared (...) in
- the outermost block of any handler associated with a
- function-try-block.
- 3.4.1/15: The function parameter names shall not be redeclared
- in the exception-declaration nor in the outermost block of a
- handler for the function-try-block. */
- else if ((VAR_P (oldlocal)
- && oldscope == current_binding_level->level_chain
- && oldscope->kind == sk_catch)
- || (TREE_CODE (oldlocal) == PARM_DECL
- && (current_binding_level->kind == sk_catch
- || (current_binding_level->level_chain->kind
- == sk_catch))
- && in_function_try_handler))
- {
- if (permerror (input_location, "redeclaration of %q#D", x))
- inform (DECL_SOURCE_LOCATION (oldlocal),
- "%q#D previously declared here", oldlocal);
- nowarn = true;
- }
-
- if ((warn_shadow
- || warn_shadow_local
- || warn_shadow_compatible_local)
- && !nowarn)
- {
- bool warned;
- enum opt_code warning_code;
- /* If '-Wshadow=compatible-local' is specified without other
- -Wshadow= flags, we will warn only when the type of the
- shadowing variable (i.e. x) can be converted to that of
- the shadowed parameter (oldlocal). The reason why we only
- check if x's type can be converted to oldlocal's type
- (but not the other way around) is because when users
- accidentally shadow a parameter, more than often they
- would use the variable thinking (mistakenly) it's still
- the parameter. It would be rare that users would use the
- variable in the place that expects the parameter but
- thinking it's a new decl. */
- if (warn_shadow)
- warning_code = OPT_Wshadow;
- else if (can_convert (TREE_TYPE (oldlocal), TREE_TYPE (x),
- tf_none))
- warning_code = OPT_Wshadow_compatible_local;
- else
- warning_code = OPT_Wshadow_local;
-
- if (TREE_CODE (oldlocal) == PARM_DECL)
- warned = warning_at (input_location, warning_code,
- "declaration of %q#D shadows a parameter", x);
- else if (is_capture_proxy (oldlocal))
- warned = warning_at (input_location, warning_code,
- "declaration of %qD shadows a lambda capture",
- x);
- else
- warned = warning_at (input_location, warning_code,
- "declaration of %qD shadows a previous local",
- x);
-
- if (warned)
- inform (DECL_SOURCE_LOCATION (oldlocal),
- "shadowed declaration is here");
- }
- }
-
- /* Maybe warn if shadowing something else. */
- else if (warn_shadow && !DECL_EXTERNAL (x)
- /* No shadow warnings for internally generated vars unless
- it's an implicit typedef (see create_implicit_typedef
- in decl.c). */
- && (! DECL_ARTIFICIAL (x) || DECL_IMPLICIT_TYPEDEF_P (x))
- /* No shadow warnings for vars made for inlining. */
- && ! DECL_FROM_INLINE (x))
- {
- tree member;
-
- if (nonlambda_method_basetype ())
- member = lookup_member (current_nonlambda_class_type (),
- name,
- /*protect=*/0,
- /*want_type=*/false,
- tf_warning_or_error);
- else
- member = NULL_TREE;
-
- if (member && !TREE_STATIC (member))
- {
- if (BASELINK_P (member))
- member = BASELINK_FUNCTIONS (member);
- member = OVL_CURRENT (member);
-
- /* Do not warn if a variable shadows a function, unless
- the variable is a function or a pointer-to-function. */
- if (TREE_CODE (member) != FUNCTION_DECL
- || TREE_CODE (x) == FUNCTION_DECL
- || TYPE_PTRFN_P (TREE_TYPE (x))
- || TYPE_PTRMEMFUNC_P (TREE_TYPE (x)))
- {
- if (warning_at (input_location, OPT_Wshadow,
- "declaration of %qD shadows a member of %qT",
- x, current_nonlambda_class_type ())
- && DECL_P (member))
- inform (DECL_SOURCE_LOCATION (member),
- "shadowed declaration is here");
- }
- }
- else if (oldglobal != NULL_TREE
- && (VAR_P (oldglobal)
- /* If the old decl is a type decl, only warn if the
- old decl is an explicit typedef or if both the
- old and new decls are type decls. */
- || (TREE_CODE (oldglobal) == TYPE_DECL
- && (!DECL_ARTIFICIAL (oldglobal)
- || TREE_CODE (x) == TYPE_DECL)))
- && !instantiating_current_function_p ())
- /* XXX shadow warnings in outer-more namespaces */
- {
- if (warning_at (input_location, OPT_Wshadow,
- "declaration of %qD shadows a "
- "global declaration", x))
- inform (DECL_SOURCE_LOCATION (oldglobal),
- "shadowed declaration is here");
- }
- }
}
if (VAR_P (x))