explorer crashes on `var auto = i32;` construct

[pk19604014]

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$ cat /tmp/crash.carbon package P api;

fn Main() -> i32 { var auto = i32; return 0; }

$ bazel run explorer:explorer /tmp/crash.carbon INFO: Invocation ID: 5382d45f-0f40-4517-b618-ae51e4db4d55 INFO: Analyzed target //explorer:explorer (0 packages loaded, 0 targets configured). INFO: Found 1 target... Target //explorer:explorer up-to-date: bazel-bin/explorer/explorer INFO: Elapsed time: 0.360s, Critical Path: 0.00s INFO: 1 process: 1 internal. INFO: Build completed successfully, 1 total action INFO: Build completed successfully, 1 total action /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/optional:911: _LIBCPP_ASSERT 'this->has_value()' failed. optional operator* called on a disengaged value Please report issues to https://github.com/carbon-language/carbon-lang/issues and include the crash backtrace. Stack dump: 0. Program arguments: /usr/local/google/home/pk19604014/.cache/bazel/_bazel_pk19604014/0c0c6d5ac7dde4460fd40f446af91e37/execroot/carbon/bazel-out/k8-fastbuild/bin/explorer/explorer /tmp/crash.carbon #0 0x0000564e337d245b backtrace /tmp/llvm-20220302-9880-1faggz0/llvm-project-13.0.1.src/compiler-rt/lib/asan/../sanitizer_common/sanitizer_common_interceptors.inc:4202:13 #1 0x0000564e33b0b56b llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /proc/self/cwd/external/llvm-project/llvm/lib/Support/Unix/Signals.inc:565:13 #2 0x0000564e33b0b80b PrintStackTraceSignalHandler(void*) /proc/self/cwd/external/llvm-project/llvm/lib/Support/Unix/Signals.inc:632:1 #3 0x0000564e33b05e68 llvm::sys::RunSignalHandlers() /proc/self/cwd/external/llvm-project/llvm/lib/Support/Signals.cpp:98:18 #4 0x0000564e33b0cdbe SignalHandler(int) /proc/self/cwd/external/llvm-project/llvm/lib/Support/Unix/Signals.inc:407:1 #5 0x00007f97e2b88200 __restore_rt (/lib/x86_64-linux-gnu/libpthread.so.0+0x12200) #6 0x00007f97e28318a1 raise ./signal/../sysdeps/unix/sysv/linux/raise.c:50:1 #7 0x00007f97e281b546 abort ./stdlib/abort.c:81:7 #8 0x0000564e33c863cf (/usr/local/google/home/pk19604014/.cache/bazel/_bazel_pk19604014/0c0c6d5ac7dde4460fd40f446af91e37/execroot/carbon/bazel-out/k8-fastbuild/bin/explorer/explorer+0x9473cf) #9 0x0000564e33878d22 std::__1::optional<Carbon::Value const*>::operator*() const & /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/optional:911:9 #10 0x0000564e338a21dd Carbon::Pattern::value() const /proc/self/cwd/./explorer/ast/pattern.h:69:48 #11 0x0000564e339493be Carbon::Interpreter::StepStmt() /proc/self/cwd/explorer/interpreter/interpreter.cpp:0:55 #12 0x0000564e3394fd8f index /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:788:12 #13 0x0000564e3394fd8f index /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1438:59 #14 0x0000564e3394fd8f __holds_alternative<1UL, Carbon::Error, Carbon::Success> /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1464:14 #15 0x0000564e3394fd8f holds_alternative<Carbon::Success, Carbon::Error, Carbon::Success> /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1470:10 #16 0x0000564e3394fd8f ok /proc/self/cwd/./common/error.h:61:36 #17 0x0000564e3394fd8f Carbon::Interpreter::Step() /proc/self/cwd/explorer/interpreter/interpreter.cpp:1428:7 #18 0x0000564e33950a65 Carbon::Interpreter::RunAllSteps(std::__1::unique_ptr<Carbon::Action, std::__1::default_deleteCarbon::Action >) /proc/self/cwd/explorer/interpreter/interpreter.cpp:0:5 #19 0x0000564e33951870 ~unique_ptr /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/__memory/unique_ptr.h:272:19 #20 0x0000564e33951870 Carbon::InterpProgram(Carbon::AST const&, Carbon::Arena*, std::__1::optionalllvm::raw_ostream*) /proc/self/cwd/explorer/interpreter/interpreter.cpp:1471:3 #21 0x0000564e3385a4a8 Carbon::ExecProgram(Carbon::Arena*, Carbon::AST, std::__1::optionalllvm::raw_ostream*) /proc/self/cwd/explorer/interpreter/exec_program.cpp:56:1 #22 0x0000564e3384c5c0 ~AST /proc/self/cwd/./explorer/ast/ast.h:17:8 #23 0x0000564e3384c5c0 Carbon::Main(llvm::StringRef, int, char**) /proc/self/cwd/explorer/main.cpp:78:3 #24 0x0000564e3384b5cc index /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:788:12 #25 0x0000564e3384b5cc index /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1438:59 #26 0x0000564e3384b5cc __holds_alternative<1UL, Carbon::Error, Carbon::Success> /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1464:14 #27 0x0000564e3384b5cc holds_alternative<Carbon::Success, Carbon::Error, Carbon::Success> /usr/local/google/home/pk19604014/.linuxbrew/Cellar/llvm/13.0.1_1/bin/../include/c++/v1/variant:1470:10 #28 0x0000564e3384b5cc ok /proc/self/cwd/./common/error.h:61:36 #29 0x0000564e3384b5cc Carbon::ExplorerMain(llvm::StringRef, int, char**) /proc/self/cwd/explorer/main.cpp:88:69 #30 0x0000564e3384aa41 main /proc/self/cwd/explorer/main_bin.cpp:0:10 #31 0x00007f97e281c7fd __libc_start_main ./csu/../csu/libc-start.c:332:16 #32 0x0000564e3379983a _start (/usr/local/google/home/pk19604014/.cache/bazel/_bazel_pk19604014/0c0c6d5ac7dde4460fd40f446af91e37/execroot/carbon/bazel-out/k8-fastbuild/bin/explorer/explorer+0x45a83a)

[pk19604014]

package ExplorerTest api;

choice Ch { Alt(i32) }

fn Main() -> i32 { var Ch.Alt(1) = Ch.Alt(2); return 0; }

$ bazel run explorer:explorer

Crashes with ... CHECK failure at explorer/interpreter/interpreter.cpp:1300: PatternMatch(p, v, stmt.source_loc(), &matches, generic_args, trace_stream_, this->arena_): explorer/testdata/basic_syntax/fail_var_pattern.carbon:25: internal error in variable definition, match failed

[pk19604014]

var 1 = 2;

CHECK failure at explorer/interpreter/interpreter.cpp:1300: PatternMatch(p, v, stmt.source_loc(), &matches, generic_args, trace_stream_, this->arena_): explorer/testdata/basic_syntax/fail_var_pattern.carbon:26: internal error in variable definition, match failed

[pk19604014]

let var var x: auto = 1; currently compiles

[github-actions[bot]]

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[chandlerc]

Closing explorer-specific issues as not-planned for now due to our decision to prioritize working on the toolchain over other implementation work in the near term: https://github.com/carbon-language/carbon-lang/blob/trunk/proposals/p3532.md