From patchwork Tue May 17 23:56:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marek Polacek X-Patchwork-Id: 54117 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 275C63857831 for ; Tue, 17 May 2022 23:57:17 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 275C63857831 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1652831837; bh=1RQjterOZAVW4CuIwvzZGPpAW/D7uzGqcZAqZvHMxNs=; h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post: List-Help:List-Subscribe:From:Reply-To:From; b=XpXlWO4bIkubAs9MxMWyLCbJGqlEwowMggVM06/jt9szzj4NO23W5YPh16MaQNVf8 Gv62vugFyl6MEXRsx1J2cuykmnnBGdyqKWPHv1iMoPQ9XQgDbx7RO86j0+NkUmyN/e 5QD468ddjiQVfs3Kor+vW/A+39ePVqwuEr41lnk4= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id B65DA385734E for ; Tue, 17 May 2022 23:56:37 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B65DA385734E Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-82-0f2NyzWYMbiVth_kBRKqiQ-1; Tue, 17 May 2022 19:56:35 -0400 X-MC-Unique: 0f2NyzWYMbiVth_kBRKqiQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 39814101AA46; Tue, 17 May 2022 23:56:35 +0000 (UTC) Received: from pdp-11.redhat.com (unknown [10.22.16.220]) by smtp.corp.redhat.com (Postfix) with ESMTP id A8C2C400DFB5; Tue, 17 May 2022 23:56:34 +0000 (UTC) To: GCC Patches , Joseph Myers Subject: [PATCH] c: Implement new -Wenum-int-mismatch warning [PR105131] Date: Tue, 17 May 2022 19:56:29 -0400 Message-Id: <20220517235629.473087-1-polacek@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.11.54.1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com X-Spam-Status: No, score=-12.5 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_NONE, TXREP, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Marek Polacek via Gcc-patches From: Marek Polacek Reply-To: Marek Polacek Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" In C, an enumerated type is compatible with char, a signed integer type, or an unsigned integer type (6.7.2.2/5). Therefore this code compiles: enum E { l = -1, z = 0, g = 1 }; int foo(void); enum E foo(void) { return z; } if the underlying type of 'enum E' is 'int' (if not, we emit an error). This is different for typedefs, where C11 permits typedefs to be redeclared to the same type, but not to compatible types. In C++, the code above is invalid. It seems desirable to emit a warning in the C case, because it is probably a mistake and definitely a portability error, given that the choice of the underlying type is implementation-defined. To that end, this patch implements a new -Wenum-int-mismatch warning. Conveniently, we already have comptypes_check_enum_int to detect such mismatches. Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk? PR c/105131 gcc/c-family/ChangeLog: * c.opt (Wenum-int-mismatch): New. gcc/c/ChangeLog: * c-decl.cc (diagnose_mismatched_decls): Warn about enum/integer type mismatches. * c-tree.h (comptypes_check_enum_int): Declare. * c-typeck.cc (comptypes): No longer static. gcc/ChangeLog: * doc/invoke.texi: Document -Wenum-int-mismatch. gcc/testsuite/ChangeLog: * gcc.dg/Wenum-int-mismatch-1.c: New test. * gcc.dg/Wenum-int-mismatch-2.c: New test. --- gcc/c-family/c.opt | 4 +++ gcc/c/c-decl.cc | 13 ++++++-- gcc/c/c-tree.h | 1 + gcc/c/c-typeck.cc | 2 +- gcc/doc/invoke.texi | 20 ++++++++++++ gcc/testsuite/gcc.dg/Wenum-int-mismatch-1.c | 35 +++++++++++++++++++++ gcc/testsuite/gcc.dg/Wenum-int-mismatch-2.c | 35 +++++++++++++++++++++ 7 files changed, 107 insertions(+), 3 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/Wenum-int-mismatch-1.c create mode 100644 gcc/testsuite/gcc.dg/Wenum-int-mismatch-2.c base-commit: 2b0c8377729a3c62a05897136666574ab939aaab diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 035b1de0d84..0cb64283261 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -638,6 +638,10 @@ Wenum-conversion C ObjC C++ ObjC++ Var(warn_enum_conversion) Init(0) Warning LangEnabledBy(C ObjC,Wextra) Warn about implicit conversion of enum types. +Wenum-int-mismatch +C ObjC Var(warn_enum_int_mismatch) Warning LangEnabledBy(C ObjC,Wall) +Warn about enum/integer type mismatches. + Werror C ObjC C++ ObjC++ ; Documented in common.opt diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc index 83655548fc4..5266a61b859 100644 --- a/gcc/c/c-decl.cc +++ b/gcc/c/c-decl.cc @@ -1993,9 +1993,12 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl, bool pedwarned = false; bool warned = false; + bool enum_and_int_p = false; auto_diagnostic_group d; - if (!comptypes (oldtype, newtype)) + int comptypes_result = comptypes_check_enum_int (oldtype, newtype, + &enum_and_int_p); + if (!comptypes_result) { if (TREE_CODE (olddecl) == FUNCTION_DECL && fndecl_built_in_p (olddecl, BUILT_IN_NORMAL) @@ -2137,6 +2140,13 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl, return false; } } + /* Warn about enum/integer type mismatches. They are compatible types + (C2X 6.7.2.2/5), but may pose portability problems. */ + else if (enum_and_int_p && TREE_CODE (newdecl) != TYPE_DECL) + warned = warning_at (DECL_SOURCE_LOCATION (newdecl), + OPT_Wenum_int_mismatch, + "conflicting types for %q+D due to enum/integer " + "mismatch; have %qT", newdecl, newtype); /* Redeclaration of a type is a constraint violation (6.7.2.3p1), but silently ignore the redeclaration if either is in a system @@ -2146,7 +2156,6 @@ diagnose_mismatched_decls (tree newdecl, tree olddecl, if (TREE_CODE (newdecl) == TYPE_DECL) { bool types_different = false; - int comptypes_result; comptypes_result = comptypes_check_different_types (oldtype, newtype, &types_different); diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h index c70f0ba5ab6..2bcb9662620 100644 --- a/gcc/c/c-tree.h +++ b/gcc/c/c-tree.h @@ -685,6 +685,7 @@ extern tree require_complete_type (location_t, tree); extern bool same_translation_unit_p (const_tree, const_tree); extern int comptypes (tree, tree); extern int comptypes_check_different_types (tree, tree, bool *); +extern int comptypes_check_enum_int (tree, tree, bool *); extern bool c_vla_type_p (const_tree); extern bool c_mark_addressable (tree, bool = false); extern void c_incomplete_type_error (location_t, const_tree, const_tree); diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc index bcfe08b82bc..4f3611f1b89 100644 --- a/gcc/c/c-typeck.cc +++ b/gcc/c/c-typeck.cc @@ -1055,7 +1055,7 @@ comptypes (tree type1, tree type2) /* Like comptypes, but if it returns non-zero because enum and int are compatible, it sets *ENUM_AND_INT_P to true. */ -static int +int comptypes_check_enum_int (tree type1, tree type2, bool *enum_and_int_p) { const struct tagged_tu_seen_cache * tagged_tu_seen_base1 = tagged_tu_seen_base; diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index e8e6d4e039b..60505bcd61f 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -349,6 +349,7 @@ Objective-C and Objective-C++ Dialects}. -Wno-div-by-zero -Wdouble-promotion @gol -Wduplicated-branches -Wduplicated-cond @gol -Wempty-body -Wno-endif-labels -Wenum-compare -Wenum-conversion @gol +-Wenum-int-mismatch @gol -Werror -Werror=* -Wexpansion-to-defined -Wfatal-errors @gol -Wfloat-conversion -Wfloat-equal -Wformat -Wformat=2 @gol -Wno-format-contains-nul -Wno-format-extra-args @gol @@ -5759,6 +5760,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}. -Wdangling-pointer=2 @gol -Wduplicate-decl-specifier @r{(C and Objective-C only)} @gol -Wenum-compare @r{(in C/ObjC; this is on by default in C++)} @gol +-Wenum-int-mismatch @r{(C and Objective-C only)} @gol -Wformat @gol -Wformat-overflow @gol -Wformat-truncation @gol @@ -8735,6 +8737,24 @@ Warn when a value of enumerated type is implicitly converted to a different enumerated type. This warning is enabled by @option{-Wextra} in C@. +@item -Wenum-int-mismatch @r{(C and Objective-C only)} +@opindex Wenum-int-mismatch +@opindex Wno-enum-int-mismatch +Warn about mismatches between an enumerated type and an integer type in +declarations. For example: + +@smallexample +enum E @{ l = -1, z = 0, g = 1 @}; +int foo(void); +enum E foo(void); +@end smallexample + +In C, an enumerated type is compatible with @code{char}, a signed +integer type, or an unsigned integer type. However, since the choice +of the underlying type of an enumerated type is implementation-defined, +such mismatches may cause portability issues. In C++, such mismatches +are an error. In C, this warning is enabled by @option{-Wall}. + @item -Wjump-misses-init @r{(C, Objective-C only)} @opindex Wjump-misses-init @opindex Wno-jump-misses-init diff --git a/gcc/testsuite/gcc.dg/Wenum-int-mismatch-1.c b/gcc/testsuite/gcc.dg/Wenum-int-mismatch-1.c new file mode 100644 index 00000000000..f71a308bc19 --- /dev/null +++ b/gcc/testsuite/gcc.dg/Wenum-int-mismatch-1.c @@ -0,0 +1,35 @@ +/* PR c/105131 */ +/* { dg-do compile } */ +/* { dg-options "-Wall" } */ + +enum E { l = -1, z = 0, g = 1 }; + +int foo(void); /* { dg-message "previous declaration" } */ +enum E foo(void) { return z; } /* { dg-warning "conflicting types" } */ + +void bar(int); /* { dg-message "previous declaration" } */ +void bar(enum E); /* { dg-warning "conflicting types" } */ + +extern int arr[10]; /* { dg-message "previous declaration" } */ +extern enum E arr[10]; /* { dg-warning "conflicting types" } */ + +extern int i; /* { dg-message "previous declaration" } */ +extern enum E i; /* { dg-warning "conflicting types" } */ + +extern int *p; /* { dg-message "previous declaration" } */ +extern enum E *p; /* { dg-warning "conflicting types" } */ + +enum E foo2(void) { return z; } /* { dg-message "previous definition" } */ +int foo2(void); /* { dg-warning "conflicting types" } */ + +void bar2(enum E); /* { dg-message "previous declaration" } */ +void bar2(int); /* { dg-warning "conflicting types" } */ + +extern enum E arr2[10]; /* { dg-message "previous declaration" } */ +extern int arr2[10]; /* { dg-warning "conflicting types" } */ + +extern enum E i2; /* { dg-message "previous declaration" } */ +extern int i2; /* { dg-warning "conflicting types" } */ + +extern enum E *p2; /* { dg-message "previous declaration" } */ +extern int *p2; /* { dg-warning "conflicting types" } */ diff --git a/gcc/testsuite/gcc.dg/Wenum-int-mismatch-2.c b/gcc/testsuite/gcc.dg/Wenum-int-mismatch-2.c new file mode 100644 index 00000000000..7296b703672 --- /dev/null +++ b/gcc/testsuite/gcc.dg/Wenum-int-mismatch-2.c @@ -0,0 +1,35 @@ +/* PR c/105131 */ +/* { dg-do compile } */ +/* { dg-options "-Wall" } */ + +enum E { l = 0, z, g }; + +unsigned int foo(void); /* { dg-message "previous declaration" } */ +enum E foo(void) { return z; } /* { dg-warning "conflicting types" } */ + +void bar(unsigned int); /* { dg-message "previous declaration" } */ +void bar(enum E); /* { dg-warning "conflicting types" } */ + +extern enum E arr[10]; /* { dg-message "previous declaration" } */ +extern unsigned int arr[10]; /* { dg-warning "conflicting types" } */ + +extern unsigned int i; /* { dg-message "previous declaration" } */ +extern enum E i; /* { dg-warning "conflicting types" } */ + +extern unsigned int *p; /* { dg-message "previous declaration" } */ +extern enum E *p; /* { dg-warning "conflicting types" } */ + +enum E foo2(void) { return z; } /* { dg-message "previous definition" } */ +unsigned int foo2(void); /* { dg-warning "conflicting types" } */ + +void bar2(enum E); /* { dg-message "previous declaration" } */ +void bar2(unsigned int); /* { dg-warning "conflicting types" } */ + +extern unsigned int arr2[10]; /* { dg-message "previous declaration" } */ +extern enum E arr2[10]; /* { dg-warning "conflicting types" } */ + +extern enum E i2; /* { dg-message "previous declaration" } */ +extern unsigned int i2; /* { dg-warning "conflicting types" } */ + +extern enum E *p2; /* { dg-message "previous declaration" } */ +extern unsigned int *p2; /* { dg-warning "conflicting types" } */