[llvm-bugs] [Bug 43221] New: Assertion failure in translation unit with exactly 1 less than a power of 2 (starting at 127) operator== overloads combined with at least one operator== template with a substitution failure
via llvm-bugs
llvm-bugs at lists.llvm.org
Wed Sep 4 18:16:38 PDT 2019
https://bugs.llvm.org/show_bug.cgi?id=43221
Bug ID: 43221
Summary: Assertion failure in translation unit with exactly 1
less than a power of 2 (starting at 127) operator==
overloads combined with at least one operator==
template with a substitution failure
Product: clang
Version: trunk
Hardware: PC
OS: Linux
Status: NEW
Severity: enhancement
Priority: P
Component: C++14
Assignee: unassignedclangbugs at nondot.org
Reporter: david at doublewise.net
CC: blitzrakete at gmail.com, erik.pilkington at gmail.com,
llvm-bugs at lists.llvm.org, richard-llvm at metafoo.co.uk
The following code causes an assertion failure in clang trunk (you can also
change test() to instantiate s<255> or s<511> for the same issue, and it keeps
going if you manually increase the template depth):
template<bool>
struct enable_if;
template<>
struct enable_if<true> {
using type = void;
};
template<typename T, typename = void>
constexpr bool always_false = false;
template<typename T>
constexpr bool always_false<
T,
decltype(foo(T()))
> = T() == T();
template<typename T, typename = typename enable_if<always_false<T>>::type>
bool operator==(T, T);
template<typename T, typename = typename enable_if<always_false<T>>::type>
void data(T);
template<int>
struct S{};
template<int x>
constexpr bool operator==(S<x>, S<x>) {
return false;
}
template<int x>
constexpr bool s = S<x>() == S<x>() and s<x - 1>;
template<>
constexpr bool s<0> = S<0>() == S<0>();
void test() {
s<127>;
}
template<typename T>
struct wrapper {
wrapper() = default;
wrapper(wrapper &&) = default;
template<typename U, typename = typename
enable_if<always_false<U>>::type>
explicit wrapper(U);
friend auto foo(wrapper w) {
data(w.m);
}
int m;
};
struct wrapper2 {
wrapper<void> m;
};
file.cpp:51:3: error: no matching function for call to 'data'
data(w.m);
^~~~
file.cpp:15:11: note: in instantiation of member function 'foo' requested here
decltype(foo(T()))
^
file.cpp:47:53: note: during template argument deduction for variable template
partial specialization 'always_false<T, decltype(foo(T()))>' [with T =
wrapper<void>]
template<typename U, typename = typename
enable_if<always_false<U>>::type>
^
file.cpp:48:11: note: in instantiation of default argument for
'wrapper<wrapper<void> >' required here
explicit wrapper(U);
^~~~~~~~~~
file.cpp:43:8: note: while substituting deduced template arguments into
function template 'wrapper' [with U = wrapper<void>, $1 = (no value)]
struct wrapper {
^
file.cpp:57:8: note: while declaring the implicit copy constructor for
'wrapper2'
struct wrapper2 {
^
file.cpp:23:6: note: candidate template ignored: substitution failure [with T =
int]: implicit instantiation of undefined template 'enable_if<false>'
void data(T);
^
clang-10: /home/david/llvm/clang/lib/AST/DeclTemplate.cpp:224: void
clang::RedeclarableTemplateDecl::addSpecializationImpl(llvm::FoldingSetVector<EntryType>
&, EntryType *, void *) [Derived = clang::VarTemplateDecl, EntryType =
clang::VarTemplateSpecializationDecl]: Assertion
`!findSpecializationImpl(Specializations, SETraits::getTemplateArgs(Entry),
CorrectInsertPos) && InsertPos == CorrectInsertPos && "given incorrect
InsertPos for specialization"' failed.
Stack dump:
0. Program arguments: /home/david/llvm/build/bin/clang-10 -cc1 -triple
x86_64-unknown-linux-gnu -emit-obj -mrelax-all -disable-free -main-file-name
file.cpp -mrelocation-model static -mthread-model posix -mframe-pointer=all
-fmath-errno -masm-verbose -mconstructor-aliases -munwind-tables
-fuse-init-array -target-cpu x86-64 -dwarf-column-info -debugger-tuning=gdb
-coverage-notes-file /dev/null.gcno -resource-dir
/home/david/llvm/build/lib/clang/10.0.0 -internal-isystem
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include/g++-v9 -internal-isystem
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include/g++-v9/x86_64-pc-linux-gnu
-internal-isystem
/usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/include/g++-v9/backward
-internal-isystem /usr/local/include -internal-isystem
/home/david/llvm/build/lib/clang/10.0.0/include -internal-externc-isystem
/include -internal-externc-isystem /usr/include -w -std=c++2a
-fdeprecated-macro -fdebug-compilation-dir /home/david/tm5/reduce -ferror-limit
19 -fmessage-length 0 -fno-implicit-modules -fobjc-runtime=gcc -fcxx-exceptions
-fexceptions -fdiagnostics-show-option -fcolor-diagnostics -o /dev/null -x c++
file.cpp
1. file.cpp:59:2: current parser token ';'
2. file.cpp:57:1: parsing struct/union/class body 'wrapper2'
#0 0x000000000313ee4d PrintStackTraceSignalHandler(void*)
(.llvm.14200593635904155002) (/home/david/llvm/build/bin/clang-10+0x313ee4d)
#1 0x000000000313c630 llvm::sys::RunSignalHandlers()
(/home/david/llvm/build/bin/clang-10+0x313c630)
#2 0x000000000313f2e8 SignalHandler(int)
(/home/david/llvm/build/bin/clang-10+0x313f2e8)
#3 0x00007fcf82ba7660 __restore_rt (/lib64/libpthread.so.0+0x14660)
#4 0x00007fcf825b8d21 raise (/lib64/libc.so.6+0x38d21)
#5 0x00007fcf825a2535 abort (/lib64/libc.so.6+0x22535)
#6 0x00007fcf825a240f _nl_load_domain.cold (/lib64/libc.so.6+0x2240f)
#7 0x00007fcf825b0712 (/lib64/libc.so.6+0x30712)
#8 0x00000000054a66ee void
clang::RedeclarableTemplateDecl::addSpecializationImpl<clang::VarTemplateDecl,
clang::VarTemplateSpecializationDecl>(llvm::FoldingSetVector<clang::VarTemplateSpecializationDecl,
llvm::SmallVector<clang::VarTemplateSpecializationDecl*, 8u> >&,
clang::VarTemplateSpecializationDecl*, void*)
(/home/david/llvm/build/bin/clang-10+0x54a66ee)
#9 0x00000000051a99a1
clang::TemplateDeclInstantiator::VisitVarTemplateSpecializationDecl(clang::VarTemplateDecl*,
clang::VarDecl*, void*, clang::TemplateArgumentListInfo const&,
llvm::ArrayRef<clang::TemplateArgument>, clang::VarTemplateSpecializationDecl*)
(/home/david/llvm/build/bin/clang-10+0x51a99a1)
#10 0x00000000051ad4e5
clang::Sema::BuildVarTemplateInstantiation(clang::VarTemplateDecl*,
clang::VarDecl*, clang::TemplateArgumentList const&,
clang::TemplateArgumentListInfo const&,
llvm::SmallVectorImpl<clang::TemplateArgument>&, clang::SourceLocation, void*,
llvm::SmallVector<clang::Sema::LateInstantiatedAttribute, 16u>*,
clang::LocalInstantiationScope*)
(/home/david/llvm/build/bin/clang-10+0x51ad4e5)
#11 0x0000000005079d1b clang::Sema::CheckVarTemplateId(clang::VarTemplateDecl*,
clang::SourceLocation, clang::SourceLocation, clang::TemplateArgumentListInfo
const&) (/home/david/llvm/build/bin/clang-10+0x5079d1b)
#12 0x000000000507aaf9 clang::Sema::CheckVarTemplateId(clang::CXXScopeSpec
const&, clang::DeclarationNameInfo const&, clang::VarTemplateDecl*,
clang::SourceLocation, clang::TemplateArgumentListInfo const*)
(/home/david/llvm/build/bin/clang-10+0x507aaf9)
#13 0x000000000517324c clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformUnresolvedLookupExpr(clang::UnresolvedLookupExpr*)
(/home/david/llvm/build/bin/clang-10+0x517324c)
#14 0x00000000051786ec clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformTemplateArgument(clang::TemplateArgumentLoc
const&, clang::TemplateArgumentLoc&, bool)
(/home/david/llvm/build/bin/clang-10+0x51786ec)
#15 0x0000000005176e14 clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformTemplateSpecializationType(clang::TypeLocBuilder&,
clang::TemplateSpecializationTypeLoc, clang::TemplateName)
(/home/david/llvm/build/bin/clang-10+0x5176e14)
#16 0x000000000517656c clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformTSIInObjectScope(clang::TypeLoc,
clang::QualType, clang::NamedDecl*, clang::CXXScopeSpec&)
(/home/david/llvm/build/bin/clang-10+0x517656c)
#17 0x0000000005165278 clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformNestedNameSpecifierLoc(clang::NestedNameSpecifierLoc,
clang::QualType, clang::NamedDecl*) (.llvm.209458239465659423)
(/home/david/llvm/build/bin/clang-10+0x5165278)
#18 0x000000000517d8af clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformDependentNameType(clang::TypeLocBuilder&,
clang::DependentNameTypeLoc, bool)
(/home/david/llvm/build/bin/clang-10+0x517d8af)
#19 0x000000000514ff48 clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*)
(.llvm.209458239465659423) (/home/david/llvm/build/bin/clang-10+0x514ff48)
#20 0x000000000507d989 SubstDefaultTemplateArgument(clang::Sema&,
clang::TemplateDecl*, clang::SourceLocation, clang::SourceLocation,
clang::TemplateTypeParmDecl*, llvm::SmallVectorImpl<clang::TemplateArgument>&)
(/home/david/llvm/build/bin/clang-10+0x507d989)
#21 0x000000000507d446
clang::Sema::SubstDefaultTemplateArgumentIfAvailable(clang::TemplateDecl*,
clang::SourceLocation, clang::SourceLocation, clang::Decl*,
llvm::SmallVectorImpl<clang::TemplateArgument>&, bool&)
(/home/david/llvm/build/bin/clang-10+0x507d446)
#22 0x000000000510b957
clang::Sema::FinishTemplateArgumentDeduction(clang::FunctionTemplateDecl*,
llvm::SmallVectorImpl<clang::DeducedTemplateArgument>&, unsigned int,
clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&,
llvm::SmallVectorImpl<clang::Sema::OriginalCallArg> const*, bool,
llvm::function_ref<bool ()>) (/home/david/llvm/build/bin/clang-10+0x510b957)
#23 0x000000000510dcc1
clang::Sema::DeduceTemplateArguments(clang::FunctionTemplateDecl*,
clang::TemplateArgumentListInfo*, llvm::ArrayRef<clang::Expr*>,
clang::FunctionDecl*&, clang::sema::TemplateDeductionInfo&, bool,
llvm::function_ref<bool (llvm::ArrayRef<clang::QualType>)>)
(/home/david/llvm/build/bin/clang-10+0x510dcc1)
#24 0x0000000004fdaff7
clang::Sema::AddTemplateOverloadCandidate(clang::FunctionTemplateDecl*,
clang::DeclAccessPair, clang::TemplateArgumentListInfo*,
llvm::ArrayRef<clang::Expr*>, clang::OverloadCandidateSet&, bool, bool, bool,
clang::CallExpr::ADLCallKind) (/home/david/llvm/build/bin/clang-10+0x4fdaff7)
#25 0x0000000004efb845 clang::Sema::LookupSpecialMember(clang::CXXRecordDecl*,
clang::Sema::CXXSpecialMember, bool, bool, bool, bool, bool)
(/home/david/llvm/build/bin/clang-10+0x4efb845)
#26 0x0000000004cc5944 defaultedSpecialMemberIsConstexpr(clang::Sema&,
clang::CXXRecordDecl*, clang::Sema::CXXSpecialMember, bool,
clang::CXXConstructorDecl*, clang::Sema::InheritedConstructorInfo*)
(/home/david/llvm/build/bin/clang-10+0x4cc5944)
#27 0x0000000004ccb81b
clang::Sema::DeclareImplicitCopyConstructor(clang::CXXRecordDecl*)
(/home/david/llvm/build/bin/clang-10+0x4ccb81b)
#28 0x0000000004ccaef3
clang::Sema::AddImplicitlyDeclaredMembersToClass(clang::CXXRecordDecl*)
(/home/david/llvm/build/bin/clang-10+0x4ccaef3)
#29 0x0000000004bf0c3a clang::Sema::ActOnFields(clang::Scope*,
clang::SourceLocation, clang::Decl*, llvm::ArrayRef<clang::Decl*>,
clang::SourceLocation, clang::SourceLocation, clang::ParsedAttributesView
const&) (/home/david/llvm/build/bin/clang-10+0x4bf0c3a)
#30 0x0000000004ccad10
clang::Sema::ActOnFinishCXXMemberSpecification(clang::Scope*,
clang::SourceLocation, clang::Decl*, clang::SourceLocation,
clang::SourceLocation, clang::ParsedAttributesView const&)
(/home/david/llvm/build/bin/clang-10+0x4ccad10)
#31 0x00000000049f5ef2
clang::Parser::ParseCXXMemberSpecification(clang::SourceLocation,
clang::SourceLocation, clang::Parser::ParsedAttributesWithRange&, unsigned int,
clang::Decl*) (/home/david/llvm/build/bin/clang-10+0x49f5ef2)
#32 0x00000000049f2f5e
clang::Parser::ParseClassSpecifier(clang::tok::TokenKind,
clang::SourceLocation, clang::DeclSpec&, clang::Parser::ParsedTemplateInfo
const&, clang::AccessSpecifier, bool, clang::Parser::DeclSpecContext,
clang::Parser::ParsedAttributesWithRange&)
(/home/david/llvm/build/bin/clang-10+0x49f2f5e)
#33 0x00000000049ae3d6
clang::Parser::ParseDeclarationSpecifiers(clang::DeclSpec&,
clang::Parser::ParsedTemplateInfo const&, clang::AccessSpecifier,
clang::Parser::DeclSpecContext, clang::Parser::LateParsedAttrList*)
(/home/david/llvm/build/bin/clang-10+0x49ae3d6)
#34 0x00000000049693da
clang::Parser::ParseDeclOrFunctionDefInternal(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec&, clang::AccessSpecifier)
(/home/david/llvm/build/bin/clang-10+0x49693da)
#35 0x0000000004968f4f
clang::Parser::ParseDeclarationOrFunctionDefinition(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec*, clang::AccessSpecifier)
(/home/david/llvm/build/bin/clang-10+0x4968f4f)
#36 0x0000000004967d79
clang::Parser::ParseExternalDeclaration(clang::Parser::ParsedAttributesWithRange&,
clang::ParsingDeclSpec*) (/home/david/llvm/build/bin/clang-10+0x4967d79)
#37 0x0000000004965a7d
clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, bool)
(/home/david/llvm/build/bin/clang-10+0x4965a7d)
#38 0x0000000004960fb4 clang::ParseAST(clang::Sema&, bool, bool)
(/home/david/llvm/build/bin/clang-10+0x4960fb4)
#39 0x0000000003ab7c1f clang::FrontendAction::Execute()
(/home/david/llvm/build/bin/clang-10+0x3ab7c1f)
#40 0x0000000003a154d8
clang::CompilerInstance::ExecuteAction(clang::FrontendAction&)
(/home/david/llvm/build/bin/clang-10+0x3a154d8)
#41 0x0000000003b64067
clang::ExecuteCompilerInvocation(clang::CompilerInstance*)
(/home/david/llvm/build/bin/clang-10+0x3b64067)
#42 0x000000000201134f cc1_main(llvm::ArrayRef<char const*>, char const*,
void*) (/home/david/llvm/build/bin/clang-10+0x201134f)
#43 0x000000000200f048 main (/home/david/llvm/build/bin/clang-10+0x200f048)
#44 0x00007fcf825a3f1b __libc_start_main (/lib64/libc.so.6+0x23f1b)
#45 0x000000000200c02a _start (/home/david/llvm/build/bin/clang-10+0x200c02a)
clang-10: error: unable to execute command: Aborted (core dumped)
clang-10: error: clang frontend command failed due to signal (use -v to see
invocation)
clang version 10.0.0 (https://github.com/llvm-project/llvm-project-20170507/
ca2448658e135c6576df4eead8b997ebede4f0fa)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/david/llvm/build/bin
clang-10: note: diagnostic msg: PLEASE submit a bug report to
https://bugs.llvm.org/ and include the crash backtrace, preprocessed source,
and associated run script.
clang-10: note: diagnostic msg:
********************
PLEASE ATTACH THE FOLLOWING FILES TO THE BUG REPORT:
Preprocessed source(s) and associated run script(s) are located at:
clang-10: note: diagnostic msg: /tmp/file-96c166.cpp
clang-10: note: diagnostic msg: /tmp/file-96c166.sh
clang-10: note: diagnostic msg:
********************
The unreduced version was slightly less sensitive to the number of overloads,
but I'm assuming that just means I could trigger the bug and crash the compiler
before it saw more overloads that would have saved it.
Prior to reducing, there were no error messages before the assertion (and I
believe the code to be valid). Also strange is this even more reduced test
case, which just gives the regular compiler errors, but I believe should not
(note that gcc gives a similar error message for this test case, so it could be
invalid for some reason unknown to me):
template<bool>
struct enable_if;
template<>
struct enable_if<true> {
using type = void;
};
template<typename T, typename = void>
constexpr bool always_false = false;
template<typename T>
constexpr bool always_false<
T,
decltype(foo(T()))
> = false;
template<typename T, typename = typename enable_if<always_false<T>>::type>
void data(T);
template<typename T>
struct wrapper {
wrapper() = default;
wrapper(wrapper &&) = default;
template<typename U, typename = typename
enable_if<always_false<U>>::type>
explicit wrapper(U);
friend auto foo(wrapper w) {
data(w.m);
}
int m;
};
struct wrapper2 {
wrapper<int> m;
};
file.cpp:30:3: error: no matching function for call to 'data'
data(w.m);
^~~~
file.cpp:15:11: note: in instantiation of member function 'foo' requested here
decltype(foo(T()))
^
file.cpp:26:53: note: during template argument deduction for variable template
partial specialization 'always_false<T, decltype(foo(T()))>' [with T =
wrapper<int>]
template<typename U, typename = typename
enable_if<always_false<U>>::type>
^
file.cpp:27:11: note: in instantiation of default argument for
'wrapper<wrapper<int> >' required here
explicit wrapper(U);
^~~~~~~~~~
file.cpp:22:8: note: while substituting deduced template arguments into
function template 'wrapper' [with U = wrapper<int>, $1 = (no value)]
struct wrapper {
^
file.cpp:36:8: note: while declaring the implicit copy constructor for
'wrapper2'
struct wrapper2 {
^
file.cpp:19:6: note: candidate template ignored: substitution failure [with T =
int]: implicit instantiation of undefined template 'enable_if<false>'
void data(T);
^
1 error generated.
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