From 84ff4775d41b716c1b862d4d91ff69127686b668 Mon Sep 17 00:00:00 2001 From: Le-Chun Wu Date: Mon, 31 Oct 2016 13:21:59 +0000 Subject: Add -Wshadow=global -Wshadow=local and -Wshadow=compatible-local. This patch from Le-Chun Wu adds two new shadow warning flags for C and C++: -Wshadow=local which warns if a local variable shadows another local variable or parameter, -Wshadow=compatible-local which warns if a local variable shadows another local variable or parameter whose type is compatible with that of the shadowing variable. It is already on the google/main branch (Google ref 39127) and was previously submitted by Diego Novillo and reviewed on http://codereview.appspot.com/4452058 I addressed the review comments and made the following changes: - Add -Wshadow=global (the default alias for -Wshadow). - Make the documented options -Wshadow=global, -Wshadow=local and -Wshadow=compatible-local (with hidden undocumented aliases -Wshadow-local and -Wshadow-compatible-local for compatibility). - The -Wshadow=global, -Wshadow=local and -Wshadow=compatible-local relationships are expressed in common.opt instead of in opts.c and documented in invoke.texi. - The "previous declaration" warnings were turned into notes and use the (now) existing infrastructure instead of duplicating the warnings. The testcases have been adjusted to expect the notes. - The conditional change in name-lookup.c for non-locals (where we don't want to change the warnings, but just check the global ones) has been dropped. - Use warning_at in c-decl.c (warn_if_shadowing). gcc/ChangeLog: 2016-10-30 Le-Chun Wu Mark Wielaard * doc/invoke.texi: Document Wshadow-local and Wshadow-compatible-local. * common.opt (Wshadow=global): New option. Default for -Wshadow. (Wshadow=local): New option. (Wshadow-local): Hidden alias for -Wshadow=local. (Wshadow=compatible-local): New option. (Wshadow-compatible-local): Hidden alias for -Wshadow=compatible-local. * doc/invoke.texi: Document Wshadow=global, Wshadow=local and Wshadow=compatible-local. gcc/c/ChangeLog: 2016-10-30 Le-Chun Wu Mark Wielaard * c-decl.c (warn_if_shadowing): Use the warning code corresponding to the given -Wshadow= variant. Use warning_at. gcc/cp/ChangeLog: 2016-10-30 Le-Chun Wu Mark Wielaard * name-lookup.c (pushdecl_maybe_friend): When emitting a shadowing warning, use the code corresponding to the given -Wshadow= variant. gcc/testsuite/ChangeLog 2016-10-30 Le-Chun Wu Mark Wielaard * gcc.dg/Wshadow-compatible-local-1.c: New test. * gcc.dg/Wshadow-local-1.c: Likewise. * gcc.dg/Wshadow-local-2.c: Likewise. * g++.dg/warn/Wshadow-compatible-local-1.C: Likewise. * g++.dg/warn/Wshadow-local-1.C: Likewise. * g++.dg/warn/Wshadow-local-2.C: Likewise. Co-Authored-By: Mark Wielaard From-SVN: r241699 --- gcc/c/c-decl.c | 43 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 6 deletions(-) (limited to 'gcc/c/c-decl.c') diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c index 136f304..3e1b7a4 100644 --- a/gcc/c/c-decl.c +++ b/gcc/c/c-decl.c @@ -2735,7 +2735,9 @@ warn_if_shadowing (tree new_decl) struct c_binding *b; /* Shadow warnings wanted? */ - if (!warn_shadow + if (!(warn_shadow + || warn_shadow_local + || warn_shadow_compatible_local) /* No shadow warnings for internally generated vars. */ || DECL_IS_BUILTIN (new_decl) /* No shadow warnings for vars made for inlining. */ @@ -2759,9 +2761,23 @@ warn_if_shadowing (tree new_decl) break; } else if (TREE_CODE (old_decl) == PARM_DECL) - warned = warning (OPT_Wshadow, - "declaration of %q+D shadows a parameter", - new_decl); + { + enum opt_code warning_code; + + /* If '-Wshadow=compatible-local' is specified without other + -Wshadow= flags, we will warn only when the types of the + shadowing variable (i.e. new_decl) and the shadowed variable + (old_decl) are compatible. */ + if (warn_shadow) + warning_code = OPT_Wshadow; + else if (comptypes (TREE_TYPE (old_decl), TREE_TYPE (new_decl))) + warning_code = OPT_Wshadow_compatible_local; + else + warning_code = OPT_Wshadow_local; + warned = warning_at (DECL_SOURCE_LOCATION (new_decl), warning_code, + "declaration of %qD shadows a parameter", + new_decl); + } else if (DECL_FILE_SCOPE_P (old_decl)) { /* Do not warn if a variable shadows a function, unless @@ -2784,8 +2800,23 @@ warn_if_shadowing (tree new_decl) break; } else - warned = warning (OPT_Wshadow, "declaration of %q+D shadows a " - "previous local", new_decl); + { + enum opt_code warning_code; + + /* If '-Wshadow=compatible-local' is specified without other + -Wshadow= flags, we will warn only when the types of the + shadowing variable (i.e. new_decl) and the shadowed variable + (old_decl) are compatible. */ + if (warn_shadow) + warning_code = OPT_Wshadow; + else if (comptypes (TREE_TYPE (old_decl), TREE_TYPE (new_decl))) + warning_code = OPT_Wshadow_compatible_local; + else + warning_code = OPT_Wshadow_local; + warned = warning_at (DECL_SOURCE_LOCATION (new_decl), warning_code, + "declaration of %qD shadows a previous local", + new_decl); + } if (warned) inform (DECL_SOURCE_LOCATION (old_decl), -- cgit v1.1