| Message ID | 51B4F72B.3090107@gmail.com |
|---|---|
| State | New |
| Headers | show |
Ping! Would anybody care to comment on this? On 06/10/2013 12:44 AM, Dimitris Papavasiliou wrote: > Hello, > > First, let me say that I have consciously broken most of the rules > mentioned about patch submission at gcc.gnu.org but I have done so in > order to spare myself from wasting time to provide a proper patch in > case the implemented functionality is not deemed worthy of approval and > adoption into GCC. If any of the implemented switches prove to be > welcome I'll be more than happy to split them into separate patches, add > test-cases and add ChangLog entries as needed. > > Two of these switches are related to a feature request I submitted a > while ago, Bug 56044 > (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56044). I won't reproduce > the entire argument here since it is available in the feature request. > The relevant functionality in the patch comes in the form of two switches: > > -Wshadow-ivars which controls the "local declaration of ‘somevar’ hides > instance variable" warning which curiously is enabled by default instead > of being controlled at least by -Wshadow. The patch changes it so that > this warning can be enabled and disabled specifically through > -Wshadow-ivars as well as with all other shadowing-related warnings > through -Wshadow. > > The reason for the extra switch is that, while searching through the > Internet for a solution to this problem I have found out that other > people are inconvenienced by this particular warning as well so it might > be useful to be able to turn it off while keeping all the other > shadowing-related warnings enabled. > > -flocal-ivars which when true, as it is by default, treats instance > variables as having local scope. If false (-fno-local-ivars) instance > variables must always be referred to as self->ivarname and references of > ivarname resolve to the local or global scope as usual. > > I've also taken the opportunity of adding another switch unrelated to > the above but related to instance variables: > > -fivar-visibility which can be set to either private, protected (the > default), public and package. This sets the default instance variable > visibility which normally is implicitly protected. My use-case for it is > basically to be able to set it to public and thus effectively disable > this visibility mechanism altogether which I find no use for and > therefore have to circumvent. I'm not sure if anyone else feels the same > way towards this but I figured it was worth a try. > > I'm attaching a preliminary patch against the current revision in case > anyone wants to have a look. The changes are very small and any blatant > mistakes should be immediately obvious. I have to admit to having > virtually no knowledge of the internals of GCC but I have tried to keep > in line with formatting guidelines and general style as well as looking > up the particulars of the way options are handled in the available > documentation to avoid blind copy-pasting. I have also tried to test the > functionality both in my own (relatively large, or at least not too > small) project and with small test programs and everything works as > expected. Finallly, I tried running the tests too but these fail to > complete both in the patched and unpatched version, possibly due to the > way I've configured GCC. > > Dimitris
Since there obviously is no interest in this patch I'm simply going to attach it to the ticket mentioned below (Bug 56044) in case someone decides to look into it in the future. If anyone should want to comment on this please do so at the bug tracker since I probably won't be following this list. Thanks, Dimitris On 06/24/2013 03:04 PM, Dimitris Papavasiliou wrote: > Ping! Would anybody care to comment on this? > > On 06/10/2013 12:44 AM, Dimitris Papavasiliou wrote: >> Hello, >> >> First, let me say that I have consciously broken most of the rules >> mentioned about patch submission at gcc.gnu.org but I have done so in >> order to spare myself from wasting time to provide a proper patch in >> case the implemented functionality is not deemed worthy of approval and >> adoption into GCC. If any of the implemented switches prove to be >> welcome I'll be more than happy to split them into separate patches, add >> test-cases and add ChangLog entries as needed. >> >> Two of these switches are related to a feature request I submitted a >> while ago, Bug 56044 >> (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56044). I won't reproduce >> the entire argument here since it is available in the feature request. >> The relevant functionality in the patch comes in the form of two >> switches: >> >> -Wshadow-ivars which controls the "local declaration of ‘somevar’ hides >> instance variable" warning which curiously is enabled by default instead >> of being controlled at least by -Wshadow. The patch changes it so that >> this warning can be enabled and disabled specifically through >> -Wshadow-ivars as well as with all other shadowing-related warnings >> through -Wshadow. >> >> The reason for the extra switch is that, while searching through the >> Internet for a solution to this problem I have found out that other >> people are inconvenienced by this particular warning as well so it might >> be useful to be able to turn it off while keeping all the other >> shadowing-related warnings enabled. >> >> -flocal-ivars which when true, as it is by default, treats instance >> variables as having local scope. If false (-fno-local-ivars) instance >> variables must always be referred to as self->ivarname and references of >> ivarname resolve to the local or global scope as usual. >> >> I've also taken the opportunity of adding another switch unrelated to >> the above but related to instance variables: >> >> -fivar-visibility which can be set to either private, protected (the >> default), public and package. This sets the default instance variable >> visibility which normally is implicitly protected. My use-case for it is >> basically to be able to set it to public and thus effectively disable >> this visibility mechanism altogether which I find no use for and >> therefore have to circumvent. I'm not sure if anyone else feels the same >> way towards this but I figured it was worth a try. >> >> I'm attaching a preliminary patch against the current revision in case >> anyone wants to have a look. The changes are very small and any blatant >> mistakes should be immediately obvious. I have to admit to having >> virtually no knowledge of the internals of GCC but I have tried to keep >> in line with formatting guidelines and general style as well as looking >> up the particulars of the way options are handled in the available >> documentation to avoid blind copy-pasting. I have also tried to test the >> functionality both in my own (relatively large, or at least not too >> small) project and with small test programs and everything works as >> expected. Finallly, I tried running the tests too but these fail to >> complete both in the patched and unpatched version, possibly due to the >> way I've configured GCC. >> >> Dimitris >
Index: gcc/c-family/c.opt =================================================================== --- gcc/c-family/c.opt (revision 199867) +++ gcc/c-family/c.opt (working copy) @@ -661,6 +661,10 @@ Wselector ObjC ObjC++ Var(warn_selector) Warning Warn if a selector has multiple methods +Wshadow-ivar +ObjC ObjC++ Var(warn_shadow_ivar) Init(-1) Warning +Warn if a local declaration hides an instance variable + Wsequence-point C ObjC C++ ObjC++ Var(warn_sequence_point) Warning LangEnabledBy(C ObjC C++ ObjC++,Wall) Warn about possible violations of sequence point rules @@ -1018,6 +1022,29 @@ fnil-receivers ObjC ObjC++ Var(flag_nil_receivers) Init(1) Assume that receivers of Objective-C messages may be nil +flocal-ivars +ObjC ObjC++ Var(flag_local_ivars) Init(1) +Allow access to instance variables as if they were local declarations within instance method implementations. + +fivar-visibility= +ObjC ObjC++ Joined RejectNegative Enum(ivar_visibility) Var(default_ivar_visibility) Init(IVAR_VISIBILITY_PROTECTED) +-fvisibility=[private|protected|public|package] Set the default symbol visibility + +Enum +Name(ivar_visibility) Type(enum ivar_visibility) UnknownError(unrecognized ivar visibility value %qs) + +EnumValue +Enum(ivar_visibility) String(private) Value(IVAR_VISIBILITY_PRIVATE) + +EnumValue +Enum(ivar_visibility) String(protected) Value(IVAR_VISIBILITY_PROTECTED) + +EnumValue +Enum(ivar_visibility) String(public) Value(IVAR_VISIBILITY_PUBLIC) + +EnumValue +Enum(ivar_visibility) String(package) Value(IVAR_VISIBILITY_PACKAGE) + fnonansi-builtins C++ ObjC++ Var(flag_no_nonansi_builtin, 0) Index: gcc/flag-types.h =================================================================== --- gcc/flag-types.h (revision 199867) +++ gcc/flag-types.h (working copy) @@ -104,6 +104,16 @@ enum symbol_visibility }; #endif +/* Enumerate Objective-c instance variable visibility settings. */ + +enum ivar_visibility +{ + IVAR_VISIBILITY_PRIVATE, + IVAR_VISIBILITY_PROTECTED, + IVAR_VISIBILITY_PUBLIC, + IVAR_VISIBILITY_PACKAGE +}; + /* The stack reuse level. */ enum stack_reuse_level { Index: gcc/objc/objc-act.c =================================================================== --- gcc/objc/objc-act.c (revision 199867) +++ gcc/objc/objc-act.c (working copy) @@ -223,7 +223,7 @@ struct imp_entry *imp_list = 0; int imp_count = 0; /* `@implementation' */ int cat_count = 0; /* `@category' */ -objc_ivar_visibility_kind objc_ivar_visibility; +objc_ivar_visibility_kind objc_ivar_visibility, objc_default_ivar_visibility; /* Use to generate method labels. */ static int method_slot = 0; @@ -391,6 +391,22 @@ objc_init (void) if (!ok) return false; + /* Determine the default visibility for instance variables. */ + switch (default_ivar_visibility) + { + case IVAR_VISIBILITY_PRIVATE: + objc_default_ivar_visibility = OBJC_IVAR_VIS_PRIVATE; + break; + case IVAR_VISIBILITY_PUBLIC: + objc_default_ivar_visibility = OBJC_IVAR_VIS_PUBLIC; + break; + case IVAR_VISIBILITY_PACKAGE: + objc_default_ivar_visibility = OBJC_IVAR_VIS_PACKAGE; + break; + default: + objc_default_ivar_visibility = OBJC_IVAR_VIS_PROTECTED; + } + /* Generate general types and push runtime-specific decls to file scope. */ synth_module_prologue (); @@ -565,7 +581,7 @@ objc_start_class_interface (tree klass, objc_interface_context = objc_ivar_context = start_class (CLASS_INTERFACE_TYPE, klass, super_class, protos, attributes); - objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED; + objc_ivar_visibility = objc_default_ivar_visibility; } void @@ -643,7 +659,7 @@ objc_start_class_implementation (tree kl = objc_ivar_context = start_class (CLASS_IMPLEMENTATION_TYPE, klass, super_class, NULL_TREE, NULL_TREE); - objc_ivar_visibility = OBJC_IVAR_VIS_PROTECTED; + objc_ivar_visibility = objc_default_ivar_visibility; } void @@ -9360,6 +9376,12 @@ objc_lookup_ivar (tree other, tree id) && other && other != error_mark_node) return other; + /* Don't look up the ivar if the user has explicitly advised against + * it with -fno-local-ivars. */ + + if (!flag_local_ivars) + return other; + /* Look up the ivar, but do not use it if it is not accessible. */ ivar = is_ivar (objc_ivar_chain, id); @@ -9376,8 +9398,11 @@ objc_lookup_ivar (tree other, tree id) && !DECL_FILE_SCOPE_P (other)) #endif { - warning (0, "local declaration of %qE hides instance variable", id); - + if (warn_shadow_ivar == 1 || (warn_shadow && warn_shadow_ivar != 0)) { + warning (warn_shadow_ivar ? OPT_Wshadow_ivar : OPT_Wshadow, + "local declaration of %qE hides instance variable", id); + } + return other; }