On 10/08/2016 15:53, Paolo Bonzini wrote:
> From: Paolo Bonzini <bonz...@gnu.org>
>
> clang recently added a new warning -Wexpansion-to-defined, which
> warns when `defined' is used outside a #if expression (including the
> case of a macro that is then used in a #if expression).
>
> While I disagree with their inclusion of the warning to -Wall, I think
> it is a good addition overall. First, it is a logical extension of the
> existing warning for breaking defined across a macro and its caller.
> Second, it is good to make these warnings for `defined' available with
> a command-line option other than -pedantic.
>
> This patch adds -Wexpansion-to-defined, and enables it automatically
> for both -pedantic (as before) and -Wextra. It also changes the warning
> from a warning to a pedwarn; this is mostly for documentation sake
> since the EnabledBy machinery would turn -pedantic-errors into
> -Werror=expansion-to-defined anyway.
>
> Bootstrapped and regression tested x86_64-pc-linux-gnu, ok?
>
> Paolo
Ping? I would like to commit this now as "posted early enough during
Stage 1 and not yet fully reviewed".
Thanks,
Paolo
> libcpp:
> 2016-08-09 Paolo Bonzini <bonz...@gnu.org>
>
> * include/cpplib.h (struct cpp_options): Add new member
> warn_expansion_to_defined.
> (CPP_W_EXPANSION_TO_DEFINED): New enum member.
> * expr.c (parse_defined): Warn for all uses of "defined"
> in macros, and tie warning to CPP_W_EXPANSION_TO_DEFINED.
> Make it a pedwarning instead of a warning.
> * system.h (HAVE_DESIGNATED_INITIALIZERS): Do not use
> "defined" in macros.
>
> gcc:
> 2016-08-09 Paolo Bonzini <bonz...@gnu.org>
>
> * system.h (HAVE_DESIGNATED_INITIALIZERS,
> HAVE_DESIGNATED_UNION_INITIALIZERS): Do not use
> "defined" in macros.
>
> gcc/c-family:
> 2016-08-09 Paolo Bonzini <bonz...@gnu.org>
>
> * c.opt (Wexpansion-to-defined): New.
>
> gcc/doc:
> 2016-08-09 Paolo Bonzini <bonz...@gnu.org>
>
> * cpp.texi (Defined): Mention -Wexpansion-to-defined.
> * cppopts.texi (Invocation): Document -Wexpansion-to-defined.
> * invoke.texi (Warning Options): Document -Wexpansion-to-defined.
>
> gcc/testsuite:
> 2016-08-09 Paolo Bonzini <bonz...@gnu.org>
>
> * gcc.dg/cpp/defined.c: Mark newly introduced warnings and
> adjust for warning->pedwarn change.
> * gcc.dg/cpp/defined-Wexpansion-to-defined.c,
> gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c,
> gcc.dg/cpp/defined-Wextra.c,
> gcc.dg/cpp/defined-Wno-expansion-to-defined.c: New testcases.
>
> Index: gcc/c-family/c.opt
> ===================================================================
> --- gcc/c-family/c.opt (revision 239276)
> +++ gcc/c-family/c.opt (working copy)
> @@ -506,6 +506,10 @@
> C ObjC C++ ObjC++ Var(warn_double_promotion) Warning
> Warn about implicit conversions from \"float\" to \"double\".
>
> +Wexpansion-to-defined
> +C ObjC C++ ObjC++ CPP(warn_expansion_to_defined)
> CppReason(CPP_W_EXPANSION_TO_DEFINED) Var(cpp_warn_expansion_to_defined)
> Init(0) Warning EnabledBy(Wextra || Wpedantic)
> +Warn if \"defined\" is used outside #if.
> +
> Wimplicit-function-declaration
> C ObjC Var(warn_implicit_function_declaration) Init(-1) Warning
> LangEnabledBy(C ObjC,Wimplicit)
> Warn about implicit function declarations.
> Index: gcc/doc/cpp.texi
> ===================================================================
> --- gcc/doc/cpp.texi (revision 239276)
> +++ gcc/doc/cpp.texi (working copy)
> @@ -3342,7 +3342,9 @@
> the C standard says the behavior is undefined. GNU cpp treats it as a
> genuine @code{defined} operator and evaluates it normally. It will warn
> wherever your code uses this feature if you use the command-line option
> -@option{-pedantic}, since other compilers may handle it differently.
> +@option{-Wpedantic}, since other compilers may handle it differently. The
> +warning is also enabled by @option{-Wextra}, and can also be enabled
> +individually with @option{-Wexpansion-to-defined}.
>
> @node Else
> @subsection Else
> Index: gcc/doc/cppopts.texi
> ===================================================================
> --- gcc/doc/cppopts.texi (revision 239276)
> +++ gcc/doc/cppopts.texi (working copy)
> @@ -120,6 +120,12 @@
> @samp{#if} directive, outside of @samp{defined}. Such identifiers are
> replaced with zero.
>
> +@item -Wexpansion-to-defined
> +@opindex Wexpansion-to-defined
> +Warn whenever @samp{defined} is encountered in the expansion of a macro
> +(including the case where the macro is expanded by an @samp{#if} directive).
> +Such usage is not portable.
> +
> @item -Wunused-macros
> @opindex Wunused-macros
> Warn about macros defined in the main file that are unused. A macro
> Index: gcc/doc/invoke.texi
> ===================================================================
> --- gcc/doc/invoke.texi (revision 239276)
> +++ gcc/doc/invoke.texi (working copy)
> @@ -4914,6 +4914,11 @@
> construct, known from C++, was introduced with ISO C99 and is by default
> allowed in GCC@. It is not supported by ISO C90. @xref{Mixed Declarations}.
>
> +@item -Wexpansion-to-defined
> +@opindex Wexpansion-to-defined
> +Warn whenever @samp{defined} is encountered in the expansion of a macro.
> +This warning is also enabled by @option{-Wpedantic} and @option{-Wextra}.
> +
> @item -Wundef
> @opindex Wundef
> @opindex Wno-undef
> Index: gcc/system.h
> ===================================================================
> --- gcc/system.h (revision 239276)
> +++ gcc/system.h (working copy)
> @@ -577,16 +577,22 @@
>
> /* 1 if we have C99 designated initializers. */
> #if !defined(HAVE_DESIGNATED_INITIALIZERS)
> +#ifdef __cplusplus
> +#define HAVE_DESIGNATED_INITIALIZERS 0
> +#else
> #define HAVE_DESIGNATED_INITIALIZERS \
> - (((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L)) \
> - && !defined(__cplusplus))
> + (((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L))
> #endif
> +#endif
>
> #if !defined(HAVE_DESIGNATED_UNION_INITIALIZERS)
> +#ifdef __cplusplus
> +#define HAVE_DESIGNATED_UNION_INITIALIZERS (GCC_VERSION >= 4007)
> +#else
> #define HAVE_DESIGNATED_UNION_INITIALIZERS \
> - (((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L)) \
> - && (!defined(__cplusplus) || (GCC_VERSION >= 4007)))
> + (((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L))
> #endif
> +#endif
>
> #if HAVE_SYS_STAT_H
> # include <sys/stat.h>
> Index: gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c
> (revision 0)
> +++ gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c
> (working copy)
> @@ -0,0 +1,30 @@
> +/* Copyright (C) 2000 Free Software Foundation, Inc. */
> +
> +/* { dg-do preprocess } */
> +/* { dg-options "-ansi -pedantic-errors -Wno-expansion-to-defined" } */
> +
> +/* Use of defined in different contexts. */
> +
> +/* Source: Neil Booth, 29 Oct 2000, Zack Weinberg 11 Dec 2000. */
> +
> +#define Z
> +
> +#define bad0 defined Z
> +#if !bad0 /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad1 defined
> +#if !bad1 Z /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#if !bad1 (Z) /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad2 defined (Z
> +#if !bad2) /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> Index: gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c (revision 0)
> +++ gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c (working copy)
> @@ -0,0 +1,30 @@
> +/* Copyright (C) 2000 Free Software Foundation, Inc. */
> +
> +/* { dg-do preprocess } */
> +/* { dg-options "-Wexpansion-to-defined" } */
> +
> +/* Use of defined in different contexts. */
> +
> +/* Source: Neil Booth, 29 Oct 2000, Zack Weinberg 11 Dec 2000. */
> +
> +#define Z
> +
> +#define bad0 defined Z
> +#if !bad0 /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad1 defined
> +#if !bad1 Z /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#if !bad1 (Z) /* { dg-warning "may not be portable" }
> */
> +#error Z is defined
> +#endif
> +
> +#define bad2 defined (Z
> +#if !bad2) /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> Index: gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c
> (revision 0)
> +++ gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c
> (working copy)
> @@ -0,0 +1,30 @@
> +/* Copyright (C) 2000 Free Software Foundation, Inc. */
> +
> +/* { dg-do preprocess } */
> +/* { dg-options "-Wextra -Wno-expansion-to-defined" } */
> +
> +/* Use of defined in different contexts. */
> +
> +/* Source: Neil Booth, 29 Oct 2000, Zack Weinberg 11 Dec 2000. */
> +
> +#define Z
> +
> +#define bad0 defined Z
> +#if !bad0 /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad1 defined
> +#if !bad1 Z /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#if !bad1 (Z) /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad2 defined (Z
> +#if !bad2) /* { dg-bogus "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> Index: gcc/testsuite/gcc.dg/cpp/defined-Wextra.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/cpp/defined-Wextra.c (revision 0)
> +++ gcc/testsuite/gcc.dg/cpp/defined-Wextra.c (working copy)
> @@ -0,0 +1,30 @@
> +/* Copyright (C) 2000 Free Software Foundation, Inc. */
> +
> +/* { dg-do preprocess } */
> +/* { dg-options "-Wextra" } */
> +
> +/* Use of defined in different contexts. */
> +
> +/* Source: Neil Booth, 29 Oct 2000, Zack Weinberg 11 Dec 2000. */
> +
> +#define Z
> +
> +#define bad0 defined Z
> +#if !bad0 /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#define bad1 defined
> +#if !bad1 Z /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> +#if !bad1 (Z) /* { dg-warning "may not be portable" }
> */
> +#error Z is defined
> +#endif
> +
> +#define bad2 defined (Z
> +#if !bad2) /* { dg-warning "may not be portable" } */
> +#error Z is defined
> +#endif
> +
> Index: gcc/testsuite/gcc.dg/cpp/defined.c
> ===================================================================
> --- gcc/testsuite/gcc.dg/cpp/defined.c (revision 239276)
> +++ gcc/testsuite/gcc.dg/cpp/defined.c (working copy)
> @@ -21,7 +21,7 @@
>
> /* The behavior of "defined" when it comes from a macro expansion is
> now documented. */
> -#if is_Z_defined
> +#if is_Z_defined /* { dg-error "may not be portable" } */
> #error Macro expanding into defined operator test 1
> #endif
>
> @@ -31,7 +31,7 @@
> #error Z is defined
> #endif
>
> -#if !is_Z_defined
> +#if !is_Z_defined /* { dg-error "may not be portable" } */
> #error Macro expanding into defined operator test 2
> #endif
>
> @@ -53,7 +53,7 @@
>
> /* The behavior of "defined" when it comes from a macro expansion is
> now documented. */
> -#if is_Z_defined
> +#if is_Z_defined /* { dg-error "may not be portable" } */
> #error Macro expanding into defined operator test 1
> #endif
>
> @@ -63,23 +63,23 @@
> #error Z is defined
> #endif
>
> -#if !is_Z_defined
> +#if !is_Z_defined /* { dg-error "may not be portable" } */
> #error Macro expanding into defined operator test 2
> #endif
>
> /* Use of defined in different contexts. */
>
> #define bad1 defined
> -#if !bad1 Z /* { dg-warning "may not be portable" } */
> +#if !bad1 Z /* { dg-error "may not be portable" } */
> #error Z is defined
> #endif
>
> -#if !bad1 (Z) /* { dg-warning "may not be portable" }
> */
> +#if !bad1 (Z) /* { dg-error "may not be portable" } */
> #error Z is defined
> #endif
>
> #define bad2 defined (Z
> -#if !bad2) /* { dg-warning "may not be portable" } */
> +#if !bad2) /* { dg-error "may not be portable" } */
> #error Z is defined
> #endif
>
> Index: libcpp/expr.c
> ===================================================================
> --- libcpp/expr.c (revision 239276)
> +++ libcpp/expr.c (working copy)
> @@ -947,9 +947,11 @@
>
> if (node)
> {
> - if (pfile->context != initial_context && CPP_PEDANTIC (pfile))
> - cpp_error (pfile, CPP_DL_WARNING,
> - "this use of \"defined\" may not be portable");
> + if ((pfile->context != initial_context
> + || initial_context != &pfile->base_context)
> + && CPP_OPTION (pfile, warn_expansion_to_defined))
> + cpp_pedwarning (pfile, CPP_W_EXPANSION_TO_DEFINED,
> + "this use of \"defined\" may not be portable");
>
> _cpp_mark_macro_used (node);
> if (!(node->flags & NODE_USED))
> Index: libcpp/include/cpplib.h
> ===================================================================
> --- libcpp/include/cpplib.h (revision 239276)
> +++ libcpp/include/cpplib.h (working copy)
> @@ -410,6 +410,10 @@
> /* Nonzero means warn if undefined identifiers are evaluated in an #if. */
> unsigned char warn_undef;
>
> + /* Nonzero means warn if "defined" is encountered in a place other than
> + an #if. */
> + unsigned char warn_expansion_to_defined;
> +
> /* Nonzero means warn of unused macros from the main file. */
> unsigned char warn_unused_macros;
>
> @@ -1025,7 +1029,8 @@
> CPP_W_DATE_TIME,
> CPP_W_PEDANTIC,
> CPP_W_C90_C99_COMPAT,
> - CPP_W_CXX11_COMPAT
> + CPP_W_CXX11_COMPAT,
> + CPP_W_EXPANSION_TO_DEFINED
> };
>
> /* Output a diagnostic of some kind. */
> Index: libcpp/system.h
> ===================================================================
> --- libcpp/system.h (revision 239276)
> +++ libcpp/system.h (working copy)
> @@ -375,10 +375,13 @@
> ??? C99 designated initializers are not supported by most C++
> compilers, including G++. -- gdr, 2005-05-18 */
> #if !defined(HAVE_DESIGNATED_INITIALIZERS)
> +#ifdef __cplusplus
> +#define HAVE_DESIGNATED_INITIALIZERS 0
> +#else
> #define HAVE_DESIGNATED_INITIALIZERS \
> - (!defined(__cplusplus) \
> - && ((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L)))
> + ((GCC_VERSION >= 2007) || (__STDC_VERSION__ >= 199901L))
> #endif
> +#endif
>
> #ifndef offsetof
> #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *) 0)->MEMBER)
>
