From 344642355ce401c27ea2d57a69d83ec554a9c2bb Mon Sep 17 00:00:00 2001 From: Simon Marchi Date: Thu, 2 Mar 2023 15:26:55 -0500 Subject: [PATCH] gdb: fix -Wmaybe-uninitialized warning in value.c MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Since commit 11470e70ea0d ("gdb: store internalvars in an std::map"), bulding with -O2, with g++ 11.3.0 on Ubuntu 22.04, I see: CXX value.o In constructor ‘internalvar::internalvar(internalvar&&)’, inlined from ‘constexpr std::pair<_T1, _T2>::pair(_U1&&, _U2&&) [with _U1 = const char*&; _U2 = internalvar; typename std::enable_if<(std::_PCC::_MoveConstructiblePair<_U1, _U2>() && std::_PCC::_ImplicitlyMoveConvertiblePair<_U1, _U2>()), bool>::type = true; _T1 = const char*; _T2 = internalvar]’ at /usr/include/c++/11/bits/stl_pair.h:353:35, inlined from ‘constexpr std::pair::type>::__type, typename std::__strip_reference_wrapper::type>::__type> std::make_pair(_T1&&, _T2&&) [with _T1 = const char*&; _T2 = internalvar]’ at /usr/include/c++/11/bits/stl_pair.h:572:72, inlined from ‘internalvar* create_internalvar(const char*)’ at /home/smarchi/src/binutils-gdb/gdb/value.c:1933:52: /home/smarchi/src/binutils-gdb/gdb/value.c:1831:8: warning: ‘.internalvar::u’ may be used uninitialized [-Wmaybe-uninitialized] 1831 | struct internalvar | ^~~~~~~~~~~ /home/smarchi/src/binutils-gdb/gdb/value.c: In function ‘internalvar* create_internalvar(const char*)’: /home/smarchi/src/binutils-gdb/gdb/value.c:1933:76: note: ‘’ declared here 1933 | auto pair = internalvars.emplace (std::make_pair (name, internalvar (name))); | ^ This is because the union field internalvar::u is not initialized when constructing the temporary internalvar object above. That object is then used for move-construction, and the (implicit) move constructor copies the uninitialized bytes of field u over from the temporary object to the new internalvar object. The compiler therefore complains that we use uninitialized bytes. I don't think it's really a problem, because the internalvar object is in the `kind == INTERNALVAR_VOID` state, in which the contents of the union is irrelevant. Still, mute the warning by default-initializing the union. Change-Id: I70c392842f35255f50d8e63f4099cb6685366fb7 Reviewed-By: Tom Tromey --- gdb/value.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/gdb/value.c b/gdb/value.c index 10a7ce033fd..7b4df338304 100644 --- a/gdb/value.c +++ b/gdb/value.c @@ -1853,7 +1853,7 @@ struct internalvar enum internalvar_kind kind = INTERNALVAR_VOID; - union internalvar_data u; + union internalvar_data u {}; }; /* Use std::map, a sorted container, to make the order of iteration (and -- 2.30.2