Attachment 241700 Details for Bug 271045 – devel/gdb: fix build with clang 16

[patch] devel/gdb: fix build with clang 16

devel__gdb-fix-clang16-build-1.diff (text/plain), 9.36 KB, created by Dimitry Andric on 2023-04-24 15:30:41 UTC

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Creator: Dimitry Andric

Created: 2023-04-24 15:30:41 UTC

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obsolete

>commit fcb00f0be1b944c1c4e03aa3ed07cf40a0c1b840
>Author: Dimitry Andric <dim@FreeBSD.org>
>Date:   2023-04-24 17:00:37 +0200
>
>    devel/gdb: fix build with clang 16
>    
>    Clang 16 has a new error about integer values being outside the valid
>    range for enum types, which shows up when building gdb:
>    
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/x86-fbsd-nat.c:20:
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/defs.h:65:
>      /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
>          integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>                                                         ^
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/x86-bsd-nat.c:20:
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/defs.h:65:
>      /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
>          integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>                                                         ^
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/x86-nat.c:20:
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/defs.h:65:
>      /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
>          integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>                                                         ^
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/windows-tdep.c:18:
>      In file included from /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/defs.h:65:
>      /wrkdirs/usr/ports/devel/gdb/work-py39/gdb-13.1/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
>          integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>                                                         ^
>    
>    Upstream already noticed this, and committed
>    https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=ae61525fcf4 as
>    a workaround, so add this as an additional patch, until gdb 13.2 is
>    released.
>
>diff --git a/devel/gdb/Makefile b/devel/gdb/Makefile
>index e5ab6cdf7409..a240a5262cdc 100644
>--- a/devel/gdb/Makefile
>+++ b/devel/gdb/Makefile
>@@ -35,6 +35,7 @@ CFLAGS+=	-DRL_NO_COMPAT
> EXCLUDE=	dejagnu expect sim texinfo intl
> EXTRACT_AFTER_ARGS=	${EXCLUDE:S/^/--exclude /}
> EXTRA_PATCHES=	${FILESDIR}/commit-a980a7d24b9
>+EXTRA_PATCHES+=	${FILESDIR}/commit-ae61525fcf4
> 
> VER=		${DISTVERSION:S/.//g}
> PLIST_SUB=	VER=${VER}
>diff --git a/devel/gdb/files/commit-ae61525fcf4 b/devel/gdb/files/commit-ae61525fcf4
>new file mode 100644
>index 000000000000..202f695b654c
>--- /dev/null
>+++ b/devel/gdb/files/commit-ae61525fcf4
>@@ -0,0 +1,128 @@
>+commit ae61525fcf456ab395d55c45492a106d1275873a
>+Author: Simon Marchi <simon.marchi@efficios.com>
>+Date:   2023-02-23 12:35:40 -0500
>+
>+    gdbsupport: ignore -Wenum-constexpr-conversion in enum-flags.h
>+    
>+    When building with clang 16, we get:
>+    
>+          CXX    gdb.o
>+        In file included from /home/smarchi/src/binutils-gdb/gdb/gdb.c:19:
>+        In file included from /home/smarchi/src/binutils-gdb/gdb/defs.h:65:
>+        /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/enum-flags.h:95:52: error: integer value -1 is outside the valid range of values [0, 15] for this enumeration type [-Wenum-constexpr-conversion]
>+            integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>+                                                           ^
>+    
>+    The error message does not make it clear in the context of which enum
>+    flag this fails (i.e. what is T in this context), but it doesn't really
>+    matter, we have similar warning/errors for many of them, if we let the
>+    build go through.
>+    
>+    clang is right that the value -1 is invalid for the enum type we cast -1
>+    to.  However, we do need this expression in order to select an integer
>+    type with the appropriate signedness.  That is, with the same signedness
>+    as the underlying type of the enum.
>+    
>+    I first wondered if that was really needed, if we couldn't use
>+    std::underlying_type for that.  It turns out that the comment just above
>+    says:
>+    
>+        /* Note that std::underlying_type<enum_type> is not what we want here,
>+           since that returns unsigned int even when the enum decays to signed
>+           int.  */
>+    
>+    I was surprised, because std::is_signed<std::underlying_type<enum_type>>
>+    returns the right thing.  So I tried replacing all this with
>+    std::underlying_type, see if that would work.  Doing so causes some
>+    build failures in unittests/enum-flags-selftests.c:
>+    
>+          CXX    unittests/enum-flags-selftests.o
>+        /home/smarchi/src/binutils-gdb/gdb/unittests/enum-flags-selftests.c:254:1: error: static assertion failed due to requirement 'gdb::is_same<selftests::enum_flags_tests::check_valid_expr254::archetype<enum_flags<s
>+        elftests::enum_flags_tests::RE>, selftests::enum_flags_tests::RE, enum_flags<selftests::enum_flags_tests::RE2>, selftests::enum_flags_tests::RE2, enum_flags<selftests::enum_flags_tests::URE>, selftests::enum_fla
>+        gs_tests::URE, int>, selftests::enum_flags_tests::check_valid_expr254::archetype<enum_flags<selftests::enum_flags_tests::RE>, selftests::enum_flags_tests::RE, enum_flags<selftests::enum_flags_tests::RE2>, selfte
>+        sts::enum_flags_tests::RE2, enum_flags<selftests::enum_flags_tests::URE>, selftests::enum_flags_tests::URE, unsigned int>>::value == true':
>+        CHECK_VALID (true,  int,  true ? EF () : EF2 ())
>+        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>+        /home/smarchi/src/binutils-gdb/gdb/unittests/enum-flags-selftests.c:91:3: note: expanded from macro 'CHECK_VALID'
>+          CHECK_VALID_EXPR_6 (EF, RE, EF2, RE2, UEF, URE, VALID, EXPR_TYPE, EXPR)
>+          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>+        /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/valid-expr.h:105:3: note: expanded from macro 'CHECK_VALID_EXPR_6'
>+          CHECK_VALID_EXPR_INT (ESC_PARENS (typename T1, typename T2,           \
>+          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>+        /home/smarchi/src/binutils-gdb/gdb/../gdbsupport/valid-expr.h:66:3: note: expanded from macro 'CHECK_VALID_EXPR_INT'
>+          static_assert (gdb::is_detected_exact<archetype<TYPES, EXPR_TYPE>,    \
>+          ^              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>+    
>+    This is a bit hard to decode, but basically enumerations have the
>+    following funny property that they decay into a signed int, even if
>+    their implicit underlying type is unsigned.  This code:
>+    
>+        enum A {};
>+        enum B {};
>+    
>+        int main() {
>+          std::cout << std::is_signed<std::underlying_type<A>::type>::value
>+                    << std::endl;
>+          std::cout << std::is_signed<std::underlying_type<B>::type>::value
>+                    << std::endl;
>+          auto result = true ? A() : B();
>+          std::cout << std::is_signed<decltype(result)>::value << std::endl;
>+        }
>+    
>+    produces:
>+    
>+        0
>+        0
>+        1
>+    
>+    So, the "CHECK_VALID" above checks that this property works for enum flags the
>+    same way as it would if you were using their underlying enum types.  And
>+    somehow, changing integer_for_size to use std::underlying_type breaks that.
>+    
>+    Since the current code does what we want, and I don't see any way of doing it
>+    differently, ignore -Wenum-constexpr-conversion around it.
>+    
>+    Change-Id: Ibc82ae7bbdb812102ae3f1dd099fc859dc6f3cc2
>+
>+diff --git gdbsupport/enum-flags.h gdbsupport/enum-flags.h
>+index 700037f6126..41ac7838f06 100644
>+--- gdbsupport/enum-flags.h
>++++ gdbsupport/enum-flags.h
>+@@ -91,9 +91,12 @@ template<> struct integer_for_size<8, 1> { typedef int64_t type; };
>+ template<typename T>
>+ struct enum_underlying_type
>+ {
>++  DIAGNOSTIC_PUSH
>++  DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
>+   typedef typename
>+     integer_for_size<sizeof (T), static_cast<bool>(T (-1) < T (0))>::type
>+     type;
>++  DIAGNOSTIC_POP
>+ };
>+ 
>+ namespace enum_flags_detail
>+diff --git include/diagnostics.h include/diagnostics.h
>+index d3ff27bc008..41e6db65391 100644
>+--- include/diagnostics.h
>++++ include/diagnostics.h
>+@@ -76,6 +76,11 @@
>+ # define DIAGNOSTIC_ERROR_SWITCH \
>+   DIAGNOSTIC_ERROR ("-Wswitch")
>+ 
>++# if __has_warning ("-Wenum-constexpr-conversion")
>++#  define DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION \
>++   DIAGNOSTIC_IGNORE ("-Wenum-constexpr-conversion")
>++# endif
>++
>+ #elif defined (__GNUC__) /* GCC */
>+ 
>+ # define DIAGNOSTIC_IGNORE_DEPRECATED_DECLARATIONS \
>+@@ -155,4 +160,8 @@
>+ # define DIAGNOSTIC_ERROR_SWITCH
>+ #endif
>+ 
>++#ifndef DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
>++# define DIAGNOSTIC_IGNORE_ENUM_CONSTEXPR_CONVERSION
>++#endif
>++
>+ #endif /* DIAGNOSTICS_H */

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Attachments on bug 271045: 241700