Compiler segfaults on auto brace initialization

[Mikadore]

Given code that tries to brace initialize an auto variable with an empty brace, or multiple values (more than one), the compiler crashes with a segmentation fault. Reproducable with the latest build on both godbolt and locally.

Example 1:

auto a{};

Example 2:

auto a{1,2};

Attached local run inside of valgrind for context (Using the first example, the include related args are due to #124 :

~/code/circle ⵃ valgrind /opt/circle/circle --nostdinc \
-I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include \
-I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include/c++ \
-I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include/c++/x86_64-pc-linux-gnu main.cxx 
==49507== Memcheck, a memory error detector
==49507== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==49507== Using Valgrind-3.19.0 and LibVEX; rerun with -h for copyright info
==49507== Command: /opt/circle/circle --nostdinc -I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include -I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include/c++ -I/usr/lib/gcc/x86_64-pc-linux-gnu/11.3.0/include/c++/x86_64-pc-linux-gnu main.cxx
==49507== 
==49507== Invalid read of size 4
==49507==    at 0x51B649: sema::stmt_builder_t::object_init(sema::decl_object_t*, std::unique_ptr<sema::arg_t, std::default_delete<sema::arg_t> >, source_loc_t) (in /opt/circle/circle)
==49507==    by 0x51C6B6: sema::stmt_builder_t::decl_init(sema::decl_t*, std::unique_ptr<sema::arg_t, std::default_delete<sema::arg_t> >, source_loc_t) (in /opt/circle/circle)
==49507==    by 0x812726: fe::decl_builder_t::declare_objectlike(fe::decl_builder_t::parse_t&, fe::range_t&, bool&) (in /opt/circle/circle)
==49507==    by 0x80F868: fe::decl_builder_t::process_declaration(fe::decl_builder_t::parse_t&, fe::range_t&, bool) (in /opt/circle/circle)
==49507==    by 0x80DA66: fe::decl_builder_t::regular_declarations(fe::range_t, bool) (in /opt/circle/circle)
==49507==    by 0x80820C: fe::decl_builder_t::parse(fe::range_t, bool) (in /opt/circle/circle)
==49507==    by 0x818A6B: fe::grammar_t::simple_declaration(fe::range_t, bool, llvm::SmallVector<std::unique_ptr<sema::template_header_t, std::default_delete<sema::template_header_t> >, 1u>*) (in /opt/circle/circle)
==49507==    by 0x8191AE: fe::grammar_t::declaration_statement(fe::range_t, bool, llvm::SmallVector<std::unique_ptr<sema::template_header_t, std::default_delete<sema::template_header_t> >, 1u>*) (in /opt/circle/circle)
==49507==    by 0x7F7254: fe::grammar_t::generic_statement(fe::range_t, meta_prefix_t) (in /opt/circle/circle)
==49507==    by 0x7F6EC4: fe::grammar_t::statement(fe::syntax_stmt_t*) (in /opt/circle/circle)
==49507==    by 0x7F6C8C: fe::grammar_t::statements(llvm::SmallVector<std::unique_ptr<fe::syntax_stmt_t, std::default_delete<fe::syntax_stmt_t> >, 2u>&) (in /opt/circle/circle)
==49507==    by 0x4433FF: main (in /opt/circle/circle)
==49507==  Address 0x9 is not stack'd, malloc'd or (recently) free'd
==49507== 
==49507== 
==49507== Process terminating with default action of signal 11 (SIGSEGV): dumping core
==49507==  Access not within mapped region at address 0x9
==49507==    at 0x51B649: sema::stmt_builder_t::object_init(sema::decl_object_t*, std::unique_ptr<sema::arg_t, std::default_delete<sema::arg_t> >, source_loc_t) (in /opt/circle/circle)
==49507==    by 0x51C6B6: sema::stmt_builder_t::decl_init(sema::decl_t*, std::unique_ptr<sema::arg_t, std::default_delete<sema::arg_t> >, source_loc_t) (in /opt/circle/circle)
==49507==    by 0x812726: fe::decl_builder_t::declare_objectlike(fe::decl_builder_t::parse_t&, fe::range_t&, bool&) (in /opt/circle/circle)
==49507==    by 0x80F868: fe::decl_builder_t::process_declaration(fe::decl_builder_t::parse_t&, fe::range_t&, bool) (in /opt/circle/circle)
==49507==    by 0x80DA66: fe::decl_builder_t::regular_declarations(fe::range_t, bool) (in /opt/circle/circle)
==49507==    by 0x80820C: fe::decl_builder_t::parse(fe::range_t, bool) (in /opt/circle/circle)
==49507==    by 0x818A6B: fe::grammar_t::simple_declaration(fe::range_t, bool, llvm::SmallVector<std::unique_ptr<sema::template_header_t, std::default_delete<sema::template_header_t> >, 1u>*) (in /opt/circle/circle)
==49507==    by 0x8191AE: fe::grammar_t::declaration_statement(fe::range_t, bool, llvm::SmallVector<std::unique_ptr<sema::template_header_t, std::default_delete<sema::template_header_t> >, 1u>*) (in /opt/circle/circle)
==49507==    by 0x7F7254: fe::grammar_t::generic_statement(fe::range_t, meta_prefix_t) (in /opt/circle/circle)
==49507==    by 0x7F6EC4: fe::grammar_t::statement(fe::syntax_stmt_t*) (in /opt/circle/circle)
==49507==    by 0x7F6C8C: fe::grammar_t::statements(llvm::SmallVector<std::unique_ptr<fe::syntax_stmt_t, std::default_delete<fe::syntax_stmt_t> >, 2u>&) (in /opt/circle/circle)
==49507==    by 0x4433FF: main (in /opt/circle/circle)
==49507==  If you believe this happened as a result of a stack
==49507==  overflow in your program's main thread (unlikely but
==49507==  possible), you can try to increase the size of the
==49507==  main thread stack using the --main-stacksize= flag.
==49507==  The main thread stack size used in this run was 8388608.
==49507== 
==49507== HEAP SUMMARY:
==49507==     in use at exit: 4,370,324 bytes in 24,898 blocks
==49507==   total heap usage: 31,842 allocs, 6,944 frees, 7,369,409 bytes allocated
==49507== 
==49507== LEAK SUMMARY:
==49507==    definitely lost: 432 bytes in 3 blocks
==49507==    indirectly lost: 0 bytes in 0 blocks
==49507==      possibly lost: 4,608 bytes in 2 blocks
==49507==    still reachable: 4,365,284 bytes in 24,893 blocks
==49507==                       of which reachable via heuristic:
==49507==                         newarray           : 34,024 bytes in 5 blocks
==49507==                         multipleinheritance: 4,160 bytes in 44 blocks
==49507==         suppressed: 0 bytes in 0 blocks
==49507== Rerun with --leak-check=full to see details of leaked memory
==49507== 
==49507== For lists of detected and suppressed errors, rerun with: -s
==49507== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

Segmentation fault (core dumped)