<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/154840>154840</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [clang][modules] RecordLayoutBuilder.cpp crash: Cannot get layout of forward declarations
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:modules,
            crash-on-valid
      </td>
    </tr>

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

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

<pre>
    This is a failure that bisects to #147835 , but I don't have a repro yet. Working on that now.

```
assertion failed at clang/lib/AST/RecordLayoutBuilder.cpp:3380 in const ASTRecordLayout &clang::ASTContext::getASTRecordLayout(const RecordDecl *) const: D && "Cannot get layout of forward declarations!"
*** Check failure stack trace: ***
    @     0x557b3889784f clang::ASTContext::getASTRecordLayout()
    @     0x557b3823cd68 clang::ASTContext::getTypeInfoImpl()
    @     0x557b3823e25c clang::ASTContext::getTypeInfo()
    @     0x557b3823d855 clang::ASTContext::getPreferredTypeAlign()
    @     0x557b3823bf01 clang::ASTContext::getDeclAlign()
    @     0x557b366c6a06 clang::CodeGen::CodeGenFunction::EmitAutoVarAlloca()
    @ 0x557b366c165c  clang::CodeGen::CodeGenFunction::EmitVarDecl()
    @ 0x557b366c1120  clang::CodeGen::CodeGenFunction::EmitDecl()
    @ 0x557b36760580  clang::CodeGen::CodeGenFunction::EmitDeclStmt()
    @ 0x557b36754d50  clang::CodeGen::CodeGenFunction::EmitSimpleStmt()
    @ 0x557b3675403e  clang::CodeGen::CodeGenFunction::EmitStmt()
    @ 0x557b36761891 clang::CodeGen::CodeGenFunction::EmitCompoundStmtWithoutScope()
    @ 0x557b368c47d5  clang::CodeGen::CodeGenFunction::GenerateCode()
    @ 0x557b368ef9f6 clang::CodeGen::CodeGenModule::EmitGlobalFunctionDefinition()
    @ 0x557b368e6bc8  clang::CodeGen::CodeGenModule::EmitGlobalDefinition()
    @ 0x557b368d7786  clang::CodeGen::CodeGenModule::EmitDeferred()
    @ 0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
...
    @ 0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @ 0x557b368d77a2  clang::CodeGen::CodeGenModule::EmitDeferred()
    @ 0x557b368d41ae  clang::CodeGen::CodeGenModule::Release()
    @ 0x557b36a1e14e  (anonymous namespace)::CodeGeneratorImpl::HandleTranslationUnit()
```
</pre>
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