llvm dev - Sep 2018 - New warnings when building trunk with GCC 9

Hello,

GCC 9.0 introduces a new warning checkers and some of them found possible
issues in LLVM.

In file included from
/home/davidbolvansky/trunk/llvm/include/llvm/Analysis/LazyCallGraph.h:38,
                 from
/home/davidbolvansky/trunk/llvm/unittests/Analysis/LazyCallGraphTest.cpp:10:
/home/davidbolvansky/trunk/llvm/include/llvm/ADT/ArrayRef.h: In
instantiation of ‘llvm::ArrayRef<T>::ArrayRef(const
std::initializer_list<_Tp>&) [with T = llvm::LazyCallGraph::Node*]’:
/home/davidbolvansky/trunk/llvm/unittests/Analysis/LazyCallGraphTest.cpp:1169:52:
 required from here
/home/davidbolvansky/trunk/llvm/include/llvm/ADT/ArrayRef.h:102:37:
warning: initializing ‘llvm::ArrayRef<llvm::LazyCallGraph::Node*>::Data’
from ‘std::initializer_list<llvm::LazyCallGraph::Node*>::begin’ does not
extend the lifetime of the underlying array [-Winit-list-lifetime]

In file included from
/home/davidbolvansky/trunk/llvm/unittests/ADT/SmallVectorTest.cpp:14:
/home/davidbolvansky/trunk/llvm/include/llvm/ADT/SmallVector.h: In member
function ‘virtual void
{anonymous}::SmallVectorTest_InitializerList_Test::TestBody()’:
/home/davidbolvansky/trunk/llvm/include/llvm/ADT/SmallVector.h:502:7:
warning: array subscript 1 is outside array bounds of ‘int [1]’
[-Warray-bounds]
502 |       ++EltPtr;
/home/davidbolvansky/trunk/llvm/unittests/ADT/SmallVectorTest.cpp:994:30:
note: while referencing ‘<anonymous>’
994 |   V2.insert(V2.begin() + 1, 5);

/home/davidbolvansky/trunk/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp:79:40:
 required from here
/home/davidbolvansky/trunk/llvm/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h:314:29:
warning: redundant move in return statement [-Wredundant-move]
314 |         return std::move(Err);

In file included from
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-spec-builders.h:75,
                 from
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-generated-function-mockers.h:43,
                 from
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock.h:61,
                 from
/home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:17,
                 from
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:15:
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:
In instantiation of
‘testing::internal::PredicateFormatterFromMatcher<M>::PredicateFormatterFromMatcher(M)
[with M = llvm::FailedMatcher]’:
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:1880:10:
 required from ‘testing::internal::PredicateFormatterFromMatcher<M>
testing::internal::MakePredicateFormatterFromMatcher(M) [with M
llvm::FailedMatcher]’
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:96:3:
 required from here
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:1836:75:
warning: implicitly-declared ‘constexpr
llvm::FailedMatcher::FailedMatcher(const llvm::FailedMatcher&)’ is
deprecated [-Wdeprecated-copy]
1836 |   explicit PredicateFormatterFromMatcher(M m) :
matcher_(internal::move(m)) {}
     |
     ^
In file included from
/home/davidbolvansky/trunk/llvm/utils/unittest/googletest/include/gtest/gtest-printers.h:103,
                 from
/home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/SupportHelpers.h:16,
                 from
/home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:15,
                 from
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:15:
/home/davidbolvansky/trunk/llvm/utils/unittest/googletest/include/gtest/internal/gtest-port.h:873:8:
note: because ‘llvm::FailedMatcher’ has user-provided ‘void
llvm::FailedMatcher::operator=(const llvm::FailedMatcher&)’
873 |   void operator=(type const &)
    |        ^~~~~~~~
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-generated-matchers.h:1417:5:
note: in expansion of macro ‘GTEST_DISALLOW_ASSIGN_’
1417 |     GTEST_DISALLOW_ASSIGN_(name##Matcher);\
     |     ^~~~~~~~~~~~~~~~~~~~~~
/home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:145:1:
note: in expansion of macro ‘MATCHER’
145 | MATCHER(Failed, "") { return !arg.Success(); }
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Great to see GCC catching the deprecated ctor case - would be great to get
that implemented in Clang at some point (& enabled for LLVM builds).
(rtrieu@)
The vector one looks like a false positive? You're allowed to form a
pointer to an element one past the end of a singular object but it looks
like that's what GCC's warning on.
Initializer list - maybe a false positive too, given ArrayRef is intended
to refer to a temporary object - I think the initializer_list's lifetime is
to teh end of the full expression where it was written, so this can still
be OK.
The ORC/redundant-move one looks correct - I wonder why Clang didn't
diagnose that (rtrieu@)?

On Thu, Sep 13, 2018 at 12:13 AM Dávid Bolvanský via llvm-dev <
llvm-dev at lists.llvm.org> wrote:
> Hello,
>
> GCC 9.0 introduces a new warning checkers and some of them found possible
> issues in LLVM.
>
> In file included from
> /home/davidbolvansky/trunk/llvm/include/llvm/Analysis/LazyCallGraph.h:38,
>                  from
>
/home/davidbolvansky/trunk/llvm/unittests/Analysis/LazyCallGraphTest.cpp:10:
> /home/davidbolvansky/trunk/llvm/include/llvm/ADT/ArrayRef.h: In
> instantiation of ‘llvm::ArrayRef<T>::ArrayRef(const
> std::initializer_list<_Tp>&) [with T =
llvm::LazyCallGraph::Node*]’:
>
/home/davidbolvansky/trunk/llvm/unittests/Analysis/LazyCallGraphTest.cpp:1169:52:
>  required from here
> /home/davidbolvansky/trunk/llvm/include/llvm/ADT/ArrayRef.h:102:37:
> warning: initializing
‘llvm::ArrayRef<llvm::LazyCallGraph::Node*>::Data’
> from ‘std::initializer_list<llvm::LazyCallGraph::Node*>::begin’ does
not
> extend the lifetime of the underlying array [-Winit-list-lifetime]
>
> In file included from
> /home/davidbolvansky/trunk/llvm/unittests/ADT/SmallVectorTest.cpp:14:
> /home/davidbolvansky/trunk/llvm/include/llvm/ADT/SmallVector.h: In member
> function ‘virtual void
> {anonymous}::SmallVectorTest_InitializerList_Test::TestBody()’:
> /home/davidbolvansky/trunk/llvm/include/llvm/ADT/SmallVector.h:502:7:
> warning: array subscript 1 is outside array bounds of ‘int [1]’
> [-Warray-bounds]
> 502 |       ++EltPtr;
> /home/davidbolvansky/trunk/llvm/unittests/ADT/SmallVectorTest.cpp:994:30:
> note: while referencing ‘<anonymous>’
> 994 |   V2.insert(V2.begin() + 1, 5);
>
>
/home/davidbolvansky/trunk/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp:79:40:
>  required from here
>
/home/davidbolvansky/trunk/llvm/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h:314:29:
> warning: redundant move in return statement [-Wredundant-move]
> 314 |         return std::move(Err);
>
> In file included from
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-spec-builders.h:75,
>                  from
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-generated-function-mockers.h:43,
>                  from
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock.h:61,
>                  from
> /home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:17,
>                  from
>
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:15:
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:
> In instantiation of
>
‘testing::internal::PredicateFormatterFromMatcher<M>::PredicateFormatterFromMatcher(M)
> [with M = llvm::FailedMatcher]’:
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:1880:10:
>  required from ‘testing::internal::PredicateFormatterFromMatcher<M>
> testing::internal::MakePredicateFormatterFromMatcher(M) [with M >
llvm::FailedMatcher]’
>
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:96:3:
>  required from here
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-matchers.h:1836:75:
> warning: implicitly-declared ‘constexpr
> llvm::FailedMatcher::FailedMatcher(const llvm::FailedMatcher&)’ is
> deprecated [-Wdeprecated-copy]
> 1836 |   explicit PredicateFormatterFromMatcher(M m) :
> matcher_(internal::move(m)) {}
>      |
>        ^
> In file included from
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googletest/include/gtest/gtest-printers.h:103,
>                  from
>
/home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/SupportHelpers.h:16,
>                  from
> /home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:15,
>                  from
>
/home/davidbolvansky/trunk/llvm/unittests/DebugInfo/MSF/MappedBlockStreamTest.cpp:15:
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googletest/include/gtest/internal/gtest-port.h:873:8:
> note: because ‘llvm::FailedMatcher’ has user-provided ‘void
> llvm::FailedMatcher::operator=(const llvm::FailedMatcher&)’
> 873 |   void operator=(type const &)
>     |        ^~~~~~~~
>
/home/davidbolvansky/trunk/llvm/utils/unittest/googlemock/include/gmock/gmock-generated-matchers.h:1417:5:
> note: in expansion of macro ‘GTEST_DISALLOW_ASSIGN_’
> 1417 |     GTEST_DISALLOW_ASSIGN_(name##Matcher);\
>      |     ^~~~~~~~~~~~~~~~~~~~~~
> /home/davidbolvansky/trunk/llvm/include/llvm/Testing/Support/Error.h:145:1:
> note: in expansion of macro ‘MATCHER’
> 145 | MATCHER(Failed, "") { return !arg.Success(); }
>
>
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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On 13/09/2018 18:22, David Blaikie via llvm-dev wrote:
> On Thu, Sep 13, 2018 at 12:13 AM Dávid Bolvanský via llvm-dev 
> <llvm-dev at lists.llvm.org <mailto:llvm-dev at
lists.llvm.org>> wrote:
>    
/home/davidbolvansky/trunk/llvm/unittests/ExecutionEngine/Orc/CompileOnDemandLayerTest.cpp:79:40:
>       required from here
>    
/home/davidbolvansky/trunk/llvm/include/llvm/ExecutionEngine/Orc/CompileOnDemandLayer.h:314:29:
>     warning: redundant move in return statement [-Wredundant-move]
>     314 |         return std::move(Err);
Note that the move (into the implicit JITSymbol(Error) ctor) is only 
redundant if the compiler implements a fix for 
<http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html#1579> 
"Return by converting move constructor".  (But not sure whether the
LLVM
compiler baselines imply that, anyway.  In LibreOffice it forced me to 
introduce ugly #ifs, to not have to disable that warning outright, 
<https://cgit.freedesktop.org/libreoffice/core/commit/?id=dc06c8f4989fc28d0c31ebd333e53dfe0e0f5f66>
"-Werror=redundant-move (GCC 9), take two".)