<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/84315>84315</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Assigning to `__real` or `__imag` of an uninitialized local complex variable at compile time asserts
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:frontend,
            constexpr
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          tbaederr
      </td>
    </tr>
</table>

<pre>
    This code:

```c++
constexpr bool b() {
  _Complex float A;// = {3.0, 3.0};
  _Complex float B = {4.0, 2.0};

  __real(A) = 4.0;
 __imag(A) = 2.0;

  return A == B;
}
static_assert(b());
```
https://godbolt.org/z/v59jxqMhE

asserts:
```
clang++: /root/llvm-project/clang/lib/AST/ExprConstant.cpp:3828: typename SubobjectHandler::result_type findSubobject({anonymous}::EvalInfo&, const clang::Expr*, const {anonymous}::CompleteObject&, const {anonymous}::SubobjectDesignator&, SubobjectHandler&) [with SubobjectHandler = {anonymous}::ModifySubobjectHandler; typename SubobjectHandler::result_type = bool]: Assertion `O->isComplexFloat()' 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>:11:1: current parser token 'static_assert'
2.      <source>:2:20: parsing function body 'b'
 #0 0x00000000038e30c8 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x38e30c8)
 #1 0x00000000038e0dac llvm::sys::CleanupOnSignal(unsigned long) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x38e0dac)
 #2 0x0000000003829088 CrashRecoverySignalHandler(int) CrashRecoveryContext.cpp:0:0
 #3 0x00007fded1642520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #4 0x00007fded16969fc pthread_kill (/lib/x86_64-linux-gnu/libc.so.6+0x969fc)
 #5 0x00007fded1642476 gsignal (/lib/x86_64-linux-gnu/libc.so.6+0x42476)
 #6 0x00007fded16287f3 abort (/lib/x86_64-linux-gnu/libc.so.6+0x287f3)
 #7 0x00007fded162871b (/lib/x86_64-linux-gnu/libc.so.6+0x2871b)
 #8 0x00007fded1639e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
 #9 0x00000000073782cc handleAssignment((anonymous namespace)::EvalInfo&, clang::Expr const*, (anonymous namespace)::LValue const&, clang::QualType, clang::APValue&) ExprConstant.cpp:0:0
#10 0x00000000073a92c2 clang::StmtVisitorBase<llvm::make_const_ptr, (anonymous namespace)::LValueExprEvaluator, bool>::Visit(clang::Stmt const*) ExprConstant.cpp:0:0
#11 0x00000000073a99cd EvaluateLValue(clang::Expr const*, (anonymous namespace)::LValue&, (anonymous namespace)::EvalInfo&, bool) ExprConstant.cpp:0:0
#12 0x0000000007380b8e Evaluate(clang::APValue&, (anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0
#13 0x00000000073818af EvaluateIgnoredValue((anonymous namespace)::EvalInfo&, clang::Expr const*) ExprConstant.cpp:0:0
#14 0x00000000073a166c EvaluateStmt((anonymous namespace)::StmtResult&, (anonymous namespace)::EvalInfo&, clang::Stmt const*, clang::SwitchCase const*) (.part.0) ExprConstant.cpp:0:0
#15 0x00000000073a18a8 EvaluateStmt((anonymous namespace)::StmtResult&, (anonymous namespace)::EvalInfo&, clang::Stmt const*, clang::SwitchCase const*) (.part.0) ExprConstant.cpp:0:0
#16 0x00000000073a6d6b HandleFunctionCall(clang::SourceLocation, clang::FunctionDecl const*, (anonymous namespace)::LValue const*, clang::Expr const*, llvm::ArrayRef<clang::Expr const*>, (anonymous namespace)::CallRef, clang::Stmt const*, (anonymous namespace)::EvalInfo&, clang::APValue&, (anonymous namespace)::LValue const*) ExprConstant.cpp:0:0
#17 0x00000000073ed8b6 clang::Expr::isPotentialConstantExpr(clang::FunctionDecl const*, llvm::SmallVectorImpl<std::pair<clang::SourceLocation, clang::PartialDiagnostic>>&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x73ed8b6)
#18 0x000000000658203f clang::Sema::CheckConstexprFunctionDefinition(clang::FunctionDecl const*, clang::Sema::CheckConstexprKind) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x658203f)
#19 0x00000000064d205b clang::Sema::ActOnFinishFunctionBody(clang::Decl*, clang::Stmt*, bool) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x64d205b)
#20 0x000000000624a08f clang::Parser::ParseFunctionStatementBody(clang::Decl*, clang::Parser::ParseScope&) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x624a08f)
#21 0x0000000006165f51 clang::Parser::ParseFunctionDefinition(clang::ParsingDeclarator&, clang::Parser::ParsedTemplateInfo const&, clang::Parser::LateParsedAttrList*) (/opt/compiler-explorer/clang-assertions-trunk/bin/clang+++0x6165f51)
[...]
```

The problem goes away when `A` is initialized before the call to `__imag` or `__real`..
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzcWFtz26oW_jXkhZFHRrIuD37wJZ7TOdnTnCbTVw9CyGYHgQ6gxN6__sxC8kV22jrd7XnYHceVxeJjfYuPxQJqrdgozqdoMkeT5R1t3VabqSsoL7kxd4Uu99PnrbCY6ZKjaIbCJQoP30nYfRgic_j4t0wr6_iuMbjQWuICkQyRHKO0b8d4vdB1I_kOV1JTh2comiOyQmSFUbQEw2gUIrLA8F-6hNb3O84P9nFnT4b2x15rw6lEJJt5P6IlBvsj6notaro5byZnzQcQw11rFJ6BAdjMTxbpsnuwjjrB1tRabhwiWc8cPkfbQ8S6n1vnGgtB9ew3uiy0dCNtNois_kJk9TrJ_9z994_t_bkvHb49zcUQk0mqNv18RDOMyMpo7RBZSflaB43Rf3IGP3u7lRQFIqvZ0zMiq_tdYxYwfVS5EWsaFM2ijGSA4_YNV7Tm-KktdAEY_6KqlNyAH9HMcNtKtwYrXAlVHq0gBumcKq32tW6tnx_ocP9K5SdVaUQSmDovGtz51LXvGoPI7NT2LkqnB8c_92MlP7A_urXkoHvqtOk7XdGC1zlGk_mbcNur5oPyrof4Q5ei2l9Haf6REAI6rB40AVQ881MutMIoCT8HKLoXtl8KK1gJB6GluKJC8nLUSeHx4X72dI9tW9TCYYqLdoMNb7Rx2Gl8IT7htm0xYrrupXKtGGFtyy0sU6pKLBSTbcmx23LMDLVbXFD24gxlHOLZGN4Yzbi1vMRWt6Z7DT2ptZoJ6niJTauwZUY0rnf5yVH2gsu2bo76DkcozB-N3hhaY2o2bc2Vlz9oWzdey7puhOQm4LtGagOz1-k7oIfI2cCZVr0gsiqEOskflgkONuUbNVUQ42CDAw24tGkAvXVN60YWBzXEAgfBLksCauvA7pWjOxQthXJc4uAJB8GGscBpLdmWCgVp4nvugbFVtLFb7XBQMS21CUpBN0pbJ5jFQaV04AM7fG1diaJln3FJiFG06MMb9WliDAEbvI5m4zF8QdBYawxXDjfUWG6w0y9cYUTSi-yVdljkHSwCfyFgAYZQG1y1inl5wnYBYMURACMShTjchYd_UcajkGXYa8wL3-5t9_BohHJeAc-djLKTkaFva22d4bTuV6xQzq9Q0P4v0QEi83DXuwfL6ej_-ML_sKTsPf8XklPVNp_VE-QW2HFa5bfXEksNo_wOb8GZgbdk6C3JwyzDCxDSF870Kzf7zr1josv6SA5sFlo5vjvsAqH_Ow4R9UOkVcnLcRKTCQjRU-u2k12WrJM4kEK1u2Cj2q6BjaweJd5x32XgdjzEzJO8YrhxW8NpuX4RUn5sAN9_MMDk0uk4TfDGbwMfxPZdB9jJEJtkaRVhWkCm_RCy7zhATq-Qx8WHMcfFADMbYkY5z5OPYfouA8z8XHVplGaEMbz1Epv5GhOyth8jO-6ZGHZD2_ilnr9fFgwLgm5r78uCHyA9fKWy5Ycel2j_aal83jf84vXs0ffqN_93yqGzhQCJIRyypjlh5BzvydXuq7DCaTOnlqNocUobNX3ha-_eunHmZkbgFESp7YqXRVcn-MSMopkfDJHswoezwN1Ca3xJK2cl7gflD32Isr89Of20fEwSnu5NLMiQRRYWGT-yGPp_Pu8fdejbYbjFyejCyXFGq6OTnzZKG14eAv7_9Cu-kMA4SdjRL5DUj_0Bqy--qP27cb2Q8LDtTTi2XVDLBwwRyUYNNQ5OhrfwnVzyzWj2T-abXPBNyqTAXUmw6qu5BZXyIpX4KvBBMwrtF44dui05kz-fqC_pXmWWUwKdGUP3X3iFosU3O0T3N3gARAHnB5Pw09P5oexyFY5bZjMdziYvsyK5Ok37J2EftePKCSoPkN1RO7tlKk_Bf6qplF85c9p8qhsJRwQ4mEBTQ4UZzsl3dfNIDXizPB5y_GZ2fziA_9qCuY_NsXSB4GXnwUsmGQmjaiAEXtNeKFvOXhaH-61TlCqhRMfspijegP1vocrfQL9nN6A_qNySuCThpHjfxRlzn9VKKGG3B25zXe6HrIHtOzx9Bp2db-C_mlrn-Tk1MijPEhLTMKsupGcP1y_--UDryVHHoWK9ld8V0hPTDf89Gu6JDJgOKrZknEyqyfgmpt8S72N3tAe21Jzdk30Ps3zmdSOhblGV_lblfd7rgTre9Zw5Zx7E-W72SyPWBeQUscl8NBqhyfLdG9Tu-3nLcWN0IXmNN5pbTN_oHr9tub-Egz5YWOxjR6X4i5e44JU2_YUYlRI7DZb99XISYm263_42OglHo7tyGpV5lNM7Ph2nYZ6N40mS3W2nacTTtErDMM6iKKU0z_MoL3M6TtI0javyTkxJSOIwCtMxITnJRmFcTWKSx3kcxymNCxSHvKZCjiBjj7TZ3Pnbu2kWR-PJnaQFl9bf-RNymJvKwJEf0g5BZAENh2QEbybLOzP1F4JFu7EoDqWwzp7gnXCST7ujnlCbI_me7JH8MRgVpgq36jyAUjMKmbK743-lRtBCckwd7jWAnag57i_A71ojpz9_iekj8b8AAAD___WRn_s">