Assert-fail on C++20 paren-agg-init of array type

[AMP999]

https://godbolt.org/z/bns6MrY9E

using T = int[1];
T a(42);

Compile with -std=c++20. Clang assert-fails with the message "Expression result is not a constant array type":

clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:11423: bool {anonymous}::ArrayExprEvaluator::VisitCXXParenListInitExpr(const clang::CXXParenListInitExpr*): Assertion `dyn_cast<ConstantArrayType>(E->getType()) && "Expression result is not a constant array type"' 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>
1.	<source>:2:8: current parser token ';'
[...]
 #8 0x000070eef7839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000075eeb0d clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::ArrayExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
#10 0x00000000075eecad EvaluateArray(clang::Expr const*, (anonymous namespace)::LValue const&, clang::APValue&, (anonymous namespace)::EvalInfo&) ExprConstant.cpp:0:0
#11 0x00000000075ba5e1 EvaluateInPlace(clang::APValue&, (anonymous namespace)::EvalInfo&, (anonymous namespace)::LValue const&, clang::Expr const*, bool) ExprConstant.cpp:0:0
#12 0x00000000075f7393 clang::Expr::EvaluateAsInitializer(clang::APValue&, clang::ASTContext const&, clang::VarDecl const*, llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75f7393)
#13 0x00000000074d1382 clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d1382)
#14 0x00000000074d16d1 clang::VarDecl::checkForConstantInitialization(llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d16d1)
#15 0x000000000663d505 clang::Sema::CheckCompleteVariableDeclaration(clang::VarDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x663d505)
#16 0x0000000006643dca clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6643dca)
[...]

The same crash happens with these variations, all of which are accepted without complaint by GCC:

using Ta = int[2]; Ta a(42);
using Tb = int[2]; Tb b(42,43);
using Tc = int[]; Tc c(42);
using Td = int[]; Td d(42,43);

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Amirreza Ashouri (AMP999)

https://godbolt.org/z/bns6MrY9E

using T = int[1];
T a(42);

Compile with -std=c++20. Clang assert-fails with the message "Expression result is not a constant array type":

clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:11423: bool {anonymous}::ArrayExprEvaluator::VisitCXXParenListInitExpr(const clang::CXXParenListInitExpr*): Assertion `dyn_cast<ConstantArrayType>(E->getType()) && "Expression result is not a constant array type"' 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>
1.	<source>:2:8: current parser token ';'
[...]
 #<!-- -->8 0x000070eef7839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #<!-- -->9 0x00000000075eeb0d clang::StmtVisitorBase&lt;llvm::make_const_ptr, (anonymous namespace)::ArrayExprEvaluator, bool&gt;::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
#<!-- -->10 0x00000000075eecad EvaluateArray(clang::Expr const*, (anonymous namespace)::LValue const&amp;, clang::APValue&amp;, (anonymous namespace)::EvalInfo&amp;) ExprConstant.cpp:0:0
#<!-- -->11 0x00000000075ba5e1 EvaluateInPlace(clang::APValue&amp;, (anonymous namespace)::EvalInfo&amp;, (anonymous namespace)::LValue const&amp;, clang::Expr const*, bool) ExprConstant.cpp:0:0
#<!-- -->12 0x00000000075f7393 clang::Expr::EvaluateAsInitializer(clang::APValue&amp;, clang::ASTContext const&amp;, clang::VarDecl const*, llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75f7393)
#<!-- -->13 0x00000000074d1382 clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d1382)
#<!-- -->14 0x00000000074d16d1 clang::VarDecl::checkForConstantInitialization(llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d16d1)
#<!-- -->15 0x000000000663d505 clang::Sema::CheckCompleteVariableDeclaration(clang::VarDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x663d505)
#<!-- -->16 0x0000000006643dca clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6643dca)
[...]

The same crash happens with these variations, all of which are accepted without complaint by GCC:

using Ta = int[2]; Ta a(42);
using Tb = int[2]; Tb b(42,43);
using Tc = int[]; Tc c(42);
using Td = int[]; Td d(42,43);

[llvmbot]

@llvm/issue-subscribers-c-20

Author: Amirreza Ashouri (AMP999)

https://godbolt.org/z/bns6MrY9E

using T = int[1];
T a(42);

Compile with -std=c++20. Clang assert-fails with the message "Expression result is not a constant array type":

clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:11423: bool {anonymous}::ArrayExprEvaluator::VisitCXXParenListInitExpr(const clang::CXXParenListInitExpr*): Assertion `dyn_cast<ConstantArrayType>(E->getType()) && "Expression result is not a constant array type"' 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>
1.	<source>:2:8: current parser token ';'
[...]
 #<!-- -->8 0x000070eef7839e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #<!-- -->9 0x00000000075eeb0d clang::StmtVisitorBase&lt;llvm::make_const_ptr, (anonymous namespace)::ArrayExprEvaluator, bool&gt;::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
#<!-- -->10 0x00000000075eecad EvaluateArray(clang::Expr const*, (anonymous namespace)::LValue const&amp;, clang::APValue&amp;, (anonymous namespace)::EvalInfo&amp;) ExprConstant.cpp:0:0
#<!-- -->11 0x00000000075ba5e1 EvaluateInPlace(clang::APValue&amp;, (anonymous namespace)::EvalInfo&amp;, (anonymous namespace)::LValue const&amp;, clang::Expr const*, bool) ExprConstant.cpp:0:0
#<!-- -->12 0x00000000075f7393 clang::Expr::EvaluateAsInitializer(clang::APValue&amp;, clang::ASTContext const&amp;, clang::VarDecl const*, llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x75f7393)
#<!-- -->13 0x00000000074d1382 clang::VarDecl::evaluateValueImpl(llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d1382)
#<!-- -->14 0x00000000074d16d1 clang::VarDecl::checkForConstantInitialization(llvm::SmallVectorImpl&lt;std::pair&lt;clang::SourceLocation, clang::PartialDiagnostic&gt;&gt;&amp;) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x74d16d1)
#<!-- -->15 0x000000000663d505 clang::Sema::CheckCompleteVariableDeclaration(clang::VarDecl*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x663d505)
#<!-- -->16 0x0000000006643dca clang::Sema::AddInitializerToDecl(clang::Decl*, clang::Expr*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6643dca)
[...]

The same crash happens with these variations, all of which are accepted without complaint by GCC:

using Ta = int[2]; Ta a(42);
using Tb = int[2]; Tb b(42,43);
using Tc = int[]; Tc c(42);
using Td = int[]; Td d(42,43);