system.h (HAVE_DESIGNATED_INITIALIZERS, [...]): Do not use "defined" in macros.

gcc:
2016-11-23  Paolo Bonzini  <bonzini@gnu.org>

	* system.h (HAVE_DESIGNATED_INITIALIZERS,
	HAVE_DESIGNATED_UNION_INITIALIZERS): Do not use
	"defined" in macros.
	* doc/cpp.texi (Defined): Mention -Wexpansion-to-defined.
	* doc/cppopts.texi (Invocation): Document -Wexpansion-to-defined.
	* doc/invoke.texi (Warning Options): Document -Wexpansion-to-defined.

gcc/c-family:
2016-11-23  Paolo Bonzini  <bonzini@gnu.org>

	* c.opt (Wexpansion-to-defined): New.

gcc/testsuite:
2016-11-23  Paolo Bonzini  <bonzini@gnu.org>

	* gcc.dg/cpp/defined.c: Mark newly introduced warnings and
	adjust for warning->pedwarn change.
	* gcc.dg/cpp/defined-syshdr.c,
	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.

libcpp:
2016-11-23  Paolo Bonzini  <bonzini@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.

From-SVN: r242743

18 files changed, 232 insertions, 18 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 92abe52..b4e5acf 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2016-11-23  Paolo Bonzini  <bonzini@gnu.org>
+
+	* system.h (HAVE_DESIGNATED_INITIALIZERS,
+	HAVE_DESIGNATED_UNION_INITIALIZERS): Do not use
+	"defined" in macros.
+	* doc/cpp.texi (Defined): Mention -Wexpansion-to-defined.
+	* doc/cppopts.texi (Invocation): Document -Wexpansion-to-defined.
+	* doc/invoke.texi (Warning Options): Document -Wexpansion-to-defined.
+
 2016-11-23  Georg-Johann Lay  <avr@gjlay.de>
 
 	PR target/60300
diff --git a/gcc/c-family/ChangeLog b/gcc/c-family/ChangeLog
index 3b41282..6b86dd2 100644
--- a/gcc/c-family/ChangeLog
+++ b/gcc/c-family/ChangeLog
@@ -1,3 +1,7 @@
+2016-11-23  Paolo Bonzini  <bonzini@gnu.org>
+
+	* c.opt (Wexpansion-to-defined): New.
+
 2016-11-23  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/78451
diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt
index c61fab8..2d47d54 100644
--- a/gcc/c-family/c.opt
+++ b/gcc/c-family/c.opt
@@ -573,6 +573,10 @@ Wdouble-promotion
 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.
diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi
index ed91767..49aa953 100644
--- a/gcc/doc/cpp.texi
+++ b/gcc/doc/cpp.texi
@@ -3369,7 +3369,9 @@ If the @code{defined} operator appears as a result of a macro expansion,
 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
diff --git a/gcc/doc/cppopts.texi b/gcc/doc/cppopts.texi
index c5f919a..e349555 100644
--- a/gcc/doc/cppopts.texi
+++ b/gcc/doc/cppopts.texi
@@ -120,6 +120,12 @@ Warn whenever an identifier which is not a macro is encountered in an
 @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
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index e026653..32c7a08 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -5320,6 +5320,11 @@ Warn when a declaration is found after a statement in a block.  This
 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
diff --git a/gcc/system.h b/gcc/system.h
index 8c6127c..3e12017 100644
--- a/gcc/system.h
+++ b/gcc/system.h
@@ -577,15 +577,21 @@ extern int vsnprintf (char *, size_t, const char *, va_list);
 
 /* 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
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 55644cd..b9ccccc 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,13 @@
+2016-11-23  Paolo Bonzini  <bonzini@gnu.org>
+
+	* gcc.dg/cpp/defined.c: Mark newly introduced warnings and
+	adjust for warning->pedwarn change.
+	* gcc.dg/cpp/defined-syshdr.c,
+	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.
+
 2016-11-23  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>
 
 	* gcc.dg/uninit-19.c: Add -finline-small-functions for avr.
diff --git a/gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c b/gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c
new file mode 100644
index 0000000..9823c76
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/defined-Wexpansion-to-defined.c
@@ -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 
+
diff --git a/gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c b/gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c
new file mode 100644
index 0000000..16a641d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/defined-Wextra-Wno-expansion-to-defined.c
@@ -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 
+
diff --git a/gcc/testsuite/gcc.dg/cpp/defined-Wextra.c b/gcc/testsuite/gcc.dg/cpp/defined-Wextra.c
new file mode 100644
index 0000000..460a1cb
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/defined-Wextra.c
@@ -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 
+
diff --git a/gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c b/gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c
new file mode 100644
index 0000000..ddd015b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/defined-Wno-expansion-to-defined.c
@@ -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 
+
diff --git a/gcc/testsuite/gcc.dg/cpp/defined-syshdr.c b/gcc/testsuite/gcc.dg/cpp/defined-syshdr.c
new file mode 100644
index 0000000..9c3846c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/defined-syshdr.c
@@ -0,0 +1,27 @@
+# 1 "defined-syshdr.c" 1
+/* { dg-do preprocess } */
+/* { dg-options "-Wexpansion-to-defined" } */
+
+#define defined_outside_sys_hdr   defined FOO
+
+# 36 "some-system-header.h" 1 3
+
+#define defined_inside_sys_hdr    defined FOO
+
+/* In a system header, it's acceptable.  */
+#if defined_outside_sys_hdr   /* { dg-bogus "may not be portable" } */
+#endif
+
+# 16 "defined-syshdr.c" 2
+
+/* Back to _not_ in a system header */
+
+#if defined_outside_sys_hdr   /* { dg-message "may not be portable" } */
+#endif
+
+/* Currently we warn about this, but it is probably a good idea not to.  */
+
+#if defined_inside_sys_hdr   /* { dg-bogus "may not be portable" "" { xfail *-*-* } } */
+#endif
+
+int x;
diff --git a/gcc/testsuite/gcc.dg/cpp/defined.c b/gcc/testsuite/gcc.dg/cpp/defined.c
index 9a60bdd..44567e4 100644
--- a/gcc/testsuite/gcc.dg/cpp/defined.c
+++ b/gcc/testsuite/gcc.dg/cpp/defined.c
@@ -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 
 
diff --git a/libcpp/ChangeLog b/libcpp/ChangeLog
index 6b92807..1a7e737 100644
--- a/libcpp/ChangeLog
+++ b/libcpp/ChangeLog
@@ -1,3 +1,14 @@
+2016-11-23  Paolo Bonzini  <bonzini@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.
+
 2016-11-17  David Malcolm  <dmalcolm@redhat.com>
 
 	* charset.c (cpp_interpret_string_1): Skip locations from
diff --git a/libcpp/expr.c b/libcpp/expr.c
index 61bc1b2..a4cf750 100644
--- a/libcpp/expr.c
+++ b/libcpp/expr.c
@@ -1031,9 +1031,11 @@ parse_defined (cpp_reader *pfile)
 
   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))
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index 0781c09..56c2491 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -415,6 +415,10 @@ struct cpp_options
   /* 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;
 
@@ -1040,7 +1044,8 @@ enum {
   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.  */
diff --git a/libcpp/system.h b/libcpp/system.h
index e89131e..67b02bb 100644
--- a/libcpp/system.h
+++ b/libcpp/system.h
@@ -375,9 +375,12 @@ extern void abort (void);
    ??? 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