<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65568>65568</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            C++17: [Boost-1.83.0] Assertion failure while parsing MemInitializer of a constructor
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang:frontend,
            new issue,
            crash
      </td>
    </tr>

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

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

<pre>
    Building Boost-1.83.0 Libraries with latest clang compiler fails.

Note: Build of the Boost-1.83.0 Libraries succeeds with cxxstd=14 instead of cxxstd=17.

$ clang++ --version
clang version 18.0.0 (https://github.com/llvm/llvm-project.git c0703eaec1df4cde861f15e244507ef79f2d3d82)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/tpki/compilers/aocc/up2-dbg/bin
$ clang++ repro.cpp -O3 -std=c++20
...
clang-18: /home/tpki/llvm-flang-src/llvm-project1/llvm/include/llvm/Support/Casting.h:578: decltype(auto) llvm::cast(From *) [To = clang::CXXConstructExpr, From = clang::Expr]: Assertion `isa
<To>(Val) && "cast<Ty>() argument of incompatible type!"' 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: /home/tpki/llvm-flang-src/llvm-project1/install_dbg/bin/clang-18 -cc ....
1.      repro.cpp:53404:1: current parser token '{'
2. repro.cpp:53390:1: parsing namespace 'boost'
3.      repro.cpp:53391:1: parsing namespace 'boost::urls'
 #0 0x00007f7104a65c7d llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) /home/tpki/llvm-flang-src/llvm-project1/llvm/lib/Support/Unix/Signals.inc:723:11
 #1 0x00007f7104a6616b PrintStackTraceSignalHandler(void*) /home/tpki/llvm-flang-src/llvm-project1/llvm/lib/Support/Unix/Signals.inc:798:1
 #2 0x00007f7104a641d6 llvm::sys::RunSignalHandlers() /home/tpki/llvm-flang-src/llvm-project1/llvm/lib/Support/Signals.cpp:105:5
 #3 0x00007f7104a66925 SignalHandler(int) /home/tpki/llvm-flang-src/llvm-project1/llvm/lib/Support/Unix/Signals.inc:413:1
 #4 0x00007f7104160520 (/lib/x86_64-linux-gnu/libc.so.6+0x42520)
 #5 0x00007f71041b4a7c __pthread_kill_implementation ./nptl/pthread_kill.c:44:76
 #6 0x00007f71041b4a7c __pthread_kill_internal ./nptl/pthread_kill.c:78:10
 #7 0x00007f71041b4a7c pthread_kill ./nptl/pthread_kill.c:89:10
 #8 0x00007f7104160476 gsignal ./signal/../sysdeps/posix/raise.c:27:6
 #9 0x00007f71041467f3 abort ./stdlib/abort.c:81:7
#10 0x00007f710414671b _nl_load_domain ./intl/loadmsgcat.c:1177:9
#11 0x00007f7104157e96 (/lib/x86_64-linux-gnu/libc.so.6+0x39e96)
#12 0x00007f70fd321018 decltype(auto) llvm::cast<clang::CXXConstructExpr, clang::Expr>(clang::Expr*) /home/tpki/llvm-flang-src/llvm-project1/llvm/include/llvm/Support/Casting.h:579:10
#13 0x00007f70fd53db82 clang::Sema::BuildDelegatingInitializer(clang::TypeSourceInfo*, clang::Expr*, clang::CXXRecordDecl*) /home/tpki/llvm-flang-src/llvm-project1/clang/lib/Sema/SemaDeclCXX.
cpp:4720:5
#14 0x00007f70fd53d01c clang::Sema::BuildBaseInitializer(clang::QualType, clang::TypeSourceInfo*, clang::Expr*, clang::CXXRecordDecl*, clang::SourceLocation) /home/tpki/llvm-flang-src/llvm-pr
oject1/clang/lib/Sema/SemaDeclCXX.cpp:4801:14
[repro.tar.gz](https://github.com/llvm/llvm-project/files/12545058/repro.tar.gz)

</pre>
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