Clang crashes when a consteval function has multiple diagnostics in flight #68542

cjdb · 2023-10-09T01:19:22Z

Apologies for the terrible title: this is difficult to summarise. Clang will crash with the following code (that's a repro of real code). Observations:

get_format and f must both be templates
get_format must be consteval
f's return statement must try to initialise something that isn't actually a member
both get_format and f need to generate a Sema diagnostic

struct S {
    int e;
};

template<class T>
consteval int get_format()
{
	return nullptr;
}

template<class T>
constexpr S f(T) noexcept
{
	return get_format<T>();
}

constexpr S x = f(0);

Observed on: dae91f5 (trunk), e19b7dc (17.0.1), not present in 16.0.0
Requires assertions: Yes.
Options: -gdwarf-4 -g -o /tmp/compiler-explorer-compiler202399-6962-m3zjz9.pmcim/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 /tmp/compiler-explorer-compiler202399-6962-m3zjz9.pmcim/example.cpp
Diagnostics:

<source>:8:9: error: cannot initialize return object of type 'int' with an rvalue of type 'std::nullptr_t'
    8 |         return nullptr;
      |                ^~~~~~~
<source>:14:9: error: no viable conversion from returned value of type 'int' to function return type 'S'
   14 |         return get_format<T>();
      |                ^~~~~~~~~~~~~~~
<source>:17:17: note: in instantiation of function template specialization 'f<int>' requested here
   17 | constexpr S x = f(0);
      |                 ^
<source>:1:8: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'int' to 'const S &' for 1st argument
    1 | struct S {
      |        ^
<source>:1:8: note: candidate constructor (the implicit move constructor) not viable: no known conversion from 'int' to 'S &&' for 1st argument
    1 | struct S {
      |        ^
<source>:17:17: error: call to immediate function 'f<int>' is not a constant expression
   17 | constexpr S x = f(0);
      |                 ^
clang++: /root/llvm-project/clang/lib/Sema/SemaDeclCXX.cpp:2492: void clang::Sema::DiagnoseImmediateEscalatingReason(clang::FunctionDecl*): Assertion `FD->hasBody() && "expected the function to have a body"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 <source> -isystem/opt/compiler-explorer/libs/glm/trunk
1.	<source>:17:21: current parser token ';'
 #0 0x00000000037217e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x37217e8)
 #1 0x000000000371f4ac llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x371f4ac)
 #2 0x0000000003668058 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007f3dc8118420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #4 0x00007f3dc7bdb00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #5 0x00007f3dc7bba859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #6 0x00007f3dc7bba729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #7 0x00007f3dc7bcbfd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #8 0x00000000062d20d5 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62d20d5)
 #9 0x00000000063bc61a EvaluateAndDiagnoseImmediateInvocation(clang::Sema&, llvm::PointerIntPair<clang::ConstantExpr*, 1u, unsigned int, llvm::PointerLikeTypeTraits<clang::ConstantExpr*>, llvm::PointerIntPairInfo<clang::ConstantExpr*, 1u, llvm::PointerLikeTypeTraits<clang::ConstantExpr*>>>) SemaExpr.cpp:0:0
#10 0x00000000063fcc9e clang::Sema::PopExpressionEvaluationContext() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x63fcc9e)
#11 0x000000000627e4c8 clang::Sema::ActOnCXXExitDeclInitializer(clang::Scope*, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x627e4c8)
#12 0x0000000005ea7837 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*)::InitializerScopeRAII::pop() ParseDecl.cpp:0:0
#13 0x0000000005eb3582 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eb3582)
#14 0x0000000005ec0c70 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ec0c70)
#15 0x0000000005e8e2eb clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e8e2eb)
#16 0x0000000005e8ea1f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#17 0x0000000005e963c4 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e963c4)
#18 0x0000000005e96bed clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e96bed)
#19 0x0000000005e89c9a clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e89c9a)
#20 0x000000000498b388 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x498b388)
#21 0x00000000041f0b09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41f0b09)
#22 0x0000000004171fde clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4171fde)
#23 0x00000000042cfcae clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42cfcae)
#24 0x0000000000bef2d6 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbef2d6)
#25 0x0000000000be6b9a ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0
#26 0x0000000003fce1a9 void llvm::function_ref<void ()>::callback_fn<clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const::'lambda'()>(long) Job.cpp:0:0
#27 0x0000000003668504 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3668504)
#28 0x0000000003fce79f clang::driver::CC1Command::Execute(llvm::ArrayRef<std::optional<llvm::StringRef>>, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>>*, bool*) const (.part.0) Job.cpp:0:0
#29 0x0000000003f96965 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f96965)
#30 0x0000000003f973cd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f973cd)
#31 0x0000000003f9f2f5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f9f2f5)
#32 0x0000000000bec77c clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbec77c)
#33 0x0000000000ae6c91 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xae6c91)
#34 0x00007f3dc7bbc083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#35 0x0000000000be667e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbe667e)

The text was updated successfully, but these errors were encountered:

shafik · 2023-10-09T02:07:43Z

CC @Fznamznon @cor3ntin

llvmbot · 2023-10-09T14:14:39Z

@llvm/issue-subscribers-clang-frontend

Apologies for the terrible title: this is difficult to summarise. Clang will crash with the following code (that's a repro of real code). Observations:

get_format and f must both be templates
get_format must be consteval
f's return statement must try to initialise something that isn't actually a member
both get_format and f need to generate a Sema diagnostic

struct S {
    int e;
};

template&lt;class T&gt;
consteval int get_format()
{
	return nullptr;
}

template&lt;class T&gt;
constexpr S f(T) noexcept
{
	return get_format&lt;T&gt;();
}

constexpr S x = f(0);

Observed on: dae91f5 (trunk), e19b7dc (17.0.1), not present in 16.0.0
Requires assertions: Yes.
Options: -gdwarf-4 -g -o /tmp/compiler-explorer-compiler202399-6962-m3zjz9.pmcim/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 /tmp/compiler-explorer-compiler202399-6962-m3zjz9.pmcim/example.cpp
Diagnostics:

&lt;source&gt;:8:9: error: cannot initialize return object of type 'int' with an rvalue of type 'std::nullptr_t'
    8 |         return nullptr;
      |                ^~~~~~~
&lt;source&gt;:14:9: error: no viable conversion from returned value of type 'int' to function return type 'S'
   14 |         return get_format&lt;T&gt;();
      |                ^~~~~~~~~~~~~~~
&lt;source&gt;:17:17: note: in instantiation of function template specialization 'f&lt;int&gt;' requested here
   17 | constexpr S x = f(0);
      |                 ^
&lt;source&gt;:1:8: note: candidate constructor (the implicit copy constructor) not viable: no known conversion from 'int' to 'const S &amp;' for 1st argument
    1 | struct S {
      |        ^
&lt;source&gt;:1:8: note: candidate constructor (the implicit move constructor) not viable: no known conversion from 'int' to 'S &amp;&amp;' for 1st argument
    1 | struct S {
      |        ^
&lt;source&gt;:17:17: error: call to immediate function 'f&lt;int&gt;' is not a constant expression
   17 | constexpr S x = f(0);
      |                 ^
clang++: /root/llvm-project/clang/lib/Sema/SemaDeclCXX.cpp:2492: void clang::Sema::DiagnoseImmediateEscalatingReason(clang::FunctionDecl*): Assertion `FD-&gt;hasBody() &amp;&amp; "expected the function to have a body"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.	Program arguments: /opt/compiler-explorer/clang-assertions-trunk/bin/clang++ -gdwarf-4 -g -o /app/output.s -mllvm --x86-asm-syntax=intel -S --gcc-toolchain=/opt/compiler-explorer/gcc-snapshot -fcolor-diagnostics -fno-crash-diagnostics -std=c++20 &lt;source&gt; -isystem/opt/compiler-explorer/libs/glm/trunk
1.	&lt;source&gt;:17:21: current parser token ';'
 #<!-- -->0 0x00000000037217e8 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x37217e8)
 #<!-- -->1 0x000000000371f4ac llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x371f4ac)
 #<!-- -->2 0x0000000003668058 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #<!-- -->3 0x00007f3dc8118420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420)
 #<!-- -->4 0x00007f3dc7bdb00b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b)
 #<!-- -->5 0x00007f3dc7bba859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859)
 #<!-- -->6 0x00007f3dc7bba729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729)
 #<!-- -->7 0x00007f3dc7bcbfd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6)
 #<!-- -->8 0x00000000062d20d5 (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x62d20d5)
 #<!-- -->9 0x00000000063bc61a EvaluateAndDiagnoseImmediateInvocation(clang::Sema&amp;, llvm::PointerIntPair&lt;clang::ConstantExpr*, 1u, unsigned int, llvm::PointerLikeTypeTraits&lt;clang::ConstantExpr*&gt;, llvm::PointerIntPairInfo&lt;clang::ConstantExpr*, 1u, llvm::PointerLikeTypeTraits&lt;clang::ConstantExpr*&gt;&gt;&gt;) SemaExpr.cpp:0:0
#<!-- -->10 0x00000000063fcc9e clang::Sema::PopExpressionEvaluationContext() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x63fcc9e)
#<!-- -->11 0x000000000627e4c8 clang::Sema::ActOnCXXExitDeclInitializer(clang::Scope*, clang::Decl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x627e4c8)
#<!-- -->12 0x0000000005ea7837 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&amp;, clang::Parser::ParsedTemplateInfo const&amp;, clang::Parser::ForRangeInit*)::InitializerScopeRAII::pop() ParseDecl.cpp:0:0
#<!-- -->13 0x0000000005eb3582 clang::Parser::ParseDeclarationAfterDeclaratorAndAttributes(clang::Declarator&amp;, clang::Parser::ParsedTemplateInfo const&amp;, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5eb3582)
#<!-- -->14 0x0000000005ec0c70 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&amp;, clang::DeclaratorContext, clang::ParsedAttributes&amp;, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5ec0c70)
#<!-- -->15 0x0000000005e8e2eb clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec&amp;, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e8e2eb)
#<!-- -->16 0x0000000005e8ea1f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0
#<!-- -->17 0x0000000005e963c4 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&amp;, clang::ParsedAttributes&amp;, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e963c4)
#<!-- -->18 0x0000000005e96bed clang::Parser::ParseTopLevelDecl(clang::OpaquePtr&lt;clang::DeclGroupRef&gt;&amp;, clang::Sema::ModuleImportState&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e96bed)
#<!-- -->19 0x0000000005e89c9a clang::ParseAST(clang::Sema&amp;, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x5e89c9a)
#<!-- -->20 0x000000000498b388 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x498b388)
#<!-- -->21 0x00000000041f0b09 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x41f0b09)
#<!-- -->22 0x0000000004171fde clang::CompilerInstance::ExecuteAction(clang::FrontendAction&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x4171fde)
#<!-- -->23 0x00000000042cfcae clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x42cfcae)
#<!-- -->24 0x0000000000bef2d6 cc1_main(llvm::ArrayRef&lt;char const*&gt;, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbef2d6)
#<!-- -->25 0x0000000000be6b9a ExecuteCC1Tool(llvm::SmallVectorImpl&lt;char const*&gt;&amp;, llvm::ToolContext const&amp;) driver.cpp:0:0
#<!-- -->26 0x0000000003fce1a9 void llvm::function_ref&lt;void ()&gt;::callback_fn&lt;clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const::'lambda'()&gt;(long) Job.cpp:0:0
#<!-- -->27 0x0000000003668504 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref&lt;void ()&gt;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3668504)
#<!-- -->28 0x0000000003fce79f clang::driver::CC1Command::Execute(llvm::ArrayRef&lt;std::optional&lt;llvm::StringRef&gt;&gt;, std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt;&gt;*, bool*) const (.part.0) Job.cpp:0:0
#<!-- -->29 0x0000000003f96965 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&amp;, clang::driver::Command const*&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f96965)
#<!-- -->30 0x0000000003f973cd clang::driver::Compilation::ExecuteJobs(clang::driver::JobList const&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f973cd)
#<!-- -->31 0x0000000003f9f2f5 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&amp;, llvm::SmallVectorImpl&lt;std::pair&lt;int, clang::driver::Command const*&gt;&gt;&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x3f9f2f5)
#<!-- -->32 0x0000000000bec77c clang_main(int, char**, llvm::ToolContext const&amp;) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbec77c)
#<!-- -->33 0x0000000000ae6c91 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xae6c91)
#<!-- -->34 0x00007f3dc7bbc083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083)
#<!-- -->35 0x0000000000be667e _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0xbe667e)

#68646) Fixes:#68542 It‘s meaningless to diagnose further error for invalid function declaration.

cjdb added clang Clang issues not falling into any other category regression labels Oct 9, 2023

EugeneZelenko added clang:frontend Language frontend issues, e.g. anything involving "Sema" crash Prefer [crash-on-valid] or [crash-on-invalid] consteval C++20 consteval and removed clang Clang issues not falling into any other category labels Oct 9, 2023

HerrCai0907 self-assigned this Oct 9, 2023

HerrCai0907 mentioned this issue Oct 10, 2023

[clang]Avoid diagnose invalid consteval call for invalid function decl #68646

Merged

HerrCai0907 added a commit that referenced this issue Oct 10, 2023

[clang]Avoid diagnose invalid consteval call for invalid function decl (

19d1da5

#68646) Fixes:#68542 It‘s meaningless to diagnose further error for invalid function declaration.

HerrCai0907 linked a pull request Oct 10, 2023 that will close this issue

[clang]Avoid diagnose invalid consteval call for invalid function decl #68646

Merged

HerrCai0907 closed this as completed Oct 10, 2023

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Clang crashes when a consteval function has multiple diagnostics in flight #68542

Clang crashes when a consteval function has multiple diagnostics in flight #68542

cjdb commented Oct 9, 2023

shafik commented Oct 9, 2023

llvmbot commented Oct 9, 2023

Clang crashes when a consteval function has multiple diagnostics in flight #68542

Clang crashes when a consteval function has multiple diagnostics in flight #68542

Comments

cjdb commented Oct 9, 2023

shafik commented Oct 9, 2023

llvmbot commented Oct 9, 2023