a[i] = b[i]; extern char b[]; extern char a[]; void foo(int j) { a[j] = b[j]; } 

<source>:1:3: error: use of undeclared identifier 'i' 1 | a[i] = b[i]; | ^ <source>:1:1: error: type specifier missing, defaults to 'int'; ISO C99 and later do not support implicit int [-Wimplicit-int] 1 | a[i] = b[i]; | ^ | int <source>:1:8: error: use of undeclared identifier 'b' 1 | a[i] = b[i]; | ^ <source>:1:10: error: use of undeclared identifier 'i' 1 | a[i] = b[i]; | ^ clang: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:1704: void {anonymous}::LValue::addUnsizedArray({anonymous}::EvalInfo&, const clang::Expr*, clang::QualType): Assertion `getType(Base)->isPointerType() || getType(Base)->isArrayType()' 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 -S --gcc-toolchain=/opt/compiler-explorer/gcc-9.2.0 -fcolor-diagnostics -fno-crash-diagnostics -O0 <source> 1.	<source>:7:1: current parser token '}' 2.	<source>:5:17: parsing function body 'foo' 3.	<source>:5:17: in compound statement ('{}') #0 0x00000000037346b8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x37346b8) #1 0x000000000373237c llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x373237c) #2 0x000000000367ac28 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0 #3 0x00007f29190b5420 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x14420) #4 0x00007f2918b7800b raise (/lib/x86_64-linux-gnu/libc.so.6+0x4300b) #5 0x00007f2918b57859 abort (/lib/x86_64-linux-gnu/libc.so.6+0x22859) #6 0x00007f2918b57729 (/lib/x86_64-linux-gnu/libc.so.6+0x22729) #7 0x00007f2918b68fd6 (/lib/x86_64-linux-gnu/libc.so.6+0x33fd6) #8 0x0000000006fbc65f (anonymous namespace)::LValue::addUnsizedArray((anonymous namespace)::EvalInfo&, clang::Expr const*, clang::QualType) ExprConstant.cpp:0:0 #9 0x000000000703f7a2 (anonymous namespace)::PointerExprEvaluator::VisitCastExpr(clang::CastExpr const*) ExprConstant.cpp:0:0 #10 0x0000000006ff69c1 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::PointerExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0 #11 0x0000000006ff7c8b EvaluatePointer(clang::Expr const*, (anonymous namespace)::LValue&, (anonymous namespace)::EvalInfo&, bool) ExprConstant.cpp:0:0 #12 0x0000000006ff93ad (anonymous namespace)::LValueExprEvaluator::VisitArraySubscriptExpr(clang::ArraySubscriptExpr const*) ExprConstant.cpp:0:0 #13 0x000000000700792e clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::LValueExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0 #14 0x00000000070094dd EvaluateLValue(clang::Expr const*, (anonymous namespace)::LValue&, (anonymous namespace)::EvalInfo&, bool) ExprConstant.cpp:0:0 #15 0x0000000006fdddfe Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0 #16 0x0000000006fe0bce (anonymous namespace)::DataRecursiveIntBinOpEvaluator::process((anonymous namespace)::DataRecursiveIntBinOpEvaluator::EvalResult&) ExprConstant.cpp:0:0 #17 0x0000000007040633 (anonymous namespace)::IntExprEvaluator::VisitBinaryOperator(clang::BinaryOperator const*) ExprConstant.cpp:0:0 #18 0x0000000006fefa4d clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::IntExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0 #19 0x0000000006fde22e Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0 #20 0x0000000006fe84b9 EvaluateAsRValue((anonymous namespace)::EvalInfo&, clang::Expr const*, clang::APValue&) ExprConstant.cpp:0:0 #21 0x0000000006fe912f clang::Expr::EvaluateForOverflow(clang::ASTContext const&) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x6fe912f) #22 0x000000000606fa85 clang::Sema::CheckForIntOverflow(clang::Expr const*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x606fa85) #23 0x00000000060c8a0d clang::Sema::CheckCompletedExpr(clang::Expr*, clang::SourceLocation, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x60c8a0d) #24 0x000000000654f4c4 clang::Sema::ActOnFinishFullExpr(clang::Expr*, clang::SourceLocation, bool, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x654f4c4) #25 0x00000000067c9eae clang::Sema::ActOnExprStmt(clang::ActionResult<clang::Expr*, true>, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x67c9eae) #26 0x0000000005f904e4 clang::Parser::ParseExprStatement(clang::Parser::ParsedStmtContext) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5f904e4) #27 0x0000000005f86aed clang::Parser::ParseStatementOrDeclarationAfterAttributes(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*, clang::ParsedAttributes&, clang::ParsedAttributes&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5f86aed) #28 0x0000000005f87928 clang::Parser::ParseStatementOrDeclaration(llvm::SmallVector<clang::Stmt*, 32u>&, clang::Parser::ParsedStmtContext, clang::SourceLocation*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5f87928) #29 0x0000000005f88869 clang::Parser::ParseCompoundStatementBody(bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5f88869) #30 0x0000000005f8a18a clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5f8a18a) #31 0x0000000005eb7ea1 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5eb7ea1) #32 0x0000000005edf3b8 clang::Parser::ParseDeclGroup(clang::ParsingDeclSpec&, clang::DeclaratorContext, clang::ParsedAttributes&, clang::SourceLocation*, clang::Parser::ForRangeInit*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5edf3b8) #33 0x0000000005eac30b clang::Parser::ParseDeclOrFunctionDefInternal(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec&, clang::AccessSpecifier) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5eac30b) #34 0x0000000005eaca3f clang::Parser::ParseDeclarationOrFunctionDefinition(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*, clang::AccessSpecifier) (.part.0) Parser.cpp:0:0 #35 0x0000000005eb43e4 clang::Parser::ParseExternalDeclaration(clang::ParsedAttributes&, clang::ParsedAttributes&, clang::ParsingDeclSpec*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5eb43e4) #36 0x0000000005eb4c0d clang::Parser::ParseTopLevelDecl(clang::OpaquePtr<clang::DeclGroupRef>&, clang::Sema::ModuleImportState&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5eb4c0d) #37 0x0000000005ea7cba clang::ParseAST(clang::Sema&, bool, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x5ea7cba) #38 0x00000000049a0c78 clang::CodeGenAction::ExecuteAction() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x49a0c78) #39 0x00000000042046a9 clang::FrontendAction::Execute() (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x42046a9) #40 0x0000000004185b4e clang::CompilerInstance::ExecuteAction(clang::FrontendAction&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x4185b4e) #41 0x00000000042e382e clang::ExecuteCompilerInvocation(clang::CompilerInstance*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x42e382e) #42 0x0000000000bf0b06 cc1_main(llvm::ArrayRef<char const*>, char const*, void*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbf0b06) #43 0x0000000000be83ca ExecuteCC1Tool(llvm::SmallVectorImpl<char const*>&, llvm::ToolContext const&) driver.cpp:0:0 #44 0x0000000003fe1d39 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 #45 0x000000000367b0d4 llvm::CrashRecoveryContext::RunSafely(llvm::function_ref<void ()>) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x367b0d4) #46 0x0000000003fe232f 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 #47 0x0000000003faa4f5 clang::driver::Compilation::ExecuteCommand(clang::driver::Command const&, clang::driver::Command const*&, bool) const (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3faa4f5) #48 0x0000000003faaf5d 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+0x3faaf5d) #49 0x0000000003fb2e85 clang::driver::Driver::ExecuteCompilation(clang::driver::Compilation&, llvm::SmallVectorImpl<std::pair<int, clang::driver::Command const*>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0x3fb2e85) #50 0x0000000000bedfac clang_main(int, char**, llvm::ToolContext const&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbedfac) #51 0x0000000000ae8141 main (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xae8141) #52 0x00007f2918b59083 __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x24083) #53 0x0000000000be7eae _start (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+0xbe7eae) clang: error: clang frontend command failed with exit code 134 (use -v to see invocation)