<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/146335>146335</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            clang crash for fopenmp statement(parallel for) inside lambda function while generating llvm-ir
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            clang
      </td>
    </tr>

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

    <tr>
      <th>Reporter</th>
      <td>
          suganyat14
      </td>
    </tr>
</table>

<pre>
    clang crashes with following stack for debug build as follows:
clang++ -fopenmp lambda_iter.cpp
lambda_iter.cpp:15:3: warning: missing 'typename' prior to dependent type name 'l::h' is a C++20 extension [-Wc++20-extensions]
   15 | l::h aa;
      |   ^
      |   typename
lambda_iter.cpp:52:20: warning: field 'q' is uninitialized when used here [-Wuninitialized]
   52 |   H(n ag, m r) : D(q, 0, ag, r, v), t{o(af, 0, 0)} {}
      | ^
lambda_iter.cpp:52:33: warning: field 'v' is uninitialized when used here [-Wuninitialized]
   52 |   H(n ag, m r) : D(q, 0, ag, r, v), t{o(af, 0, 0)} {}
      |                                 ^
lambda_iter.cpp:52:41: warning: field 'af' is uninitialized when used here [-Wuninitialized]
   52 |   H(n ag, m r) : D(q, 0, ag, r, v), t{o(af, 0, 0)} {}
      | ^
DeclRefExpr for Decl not entered in LocalDeclMap?
UNREACHABLE executed at /home/suganya/upstream_llvm/llvm-project/clang/lib/CodeGen/CGExpr.cpp:3260!
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/suganya/upstream_llvm/build/bin/clang-21 -cc1 -triple x86_64-unknown-linux-gnu -emit-obj -dumpdir a- -disable-free -clear-ast-before-backend -main-file-name lambda_iter.cpp -mrelocation-model pic -pic-level 2 -pic-is-pie -mframe-pointer=all -fmath-errno -ffp-contract=on -fno-rounding-math -mconstructor-aliases -funwind-tables=2 -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fdebug-compilation-dir=/home/suganya -fcoverage-compilation-dir=/home/suganya -resource-dir /home/suganya/upstream_llvm/build/lib/clang/21 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/x86_64-linux-gnu/c++/11 -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../include/c++/11/backward -internal-isystem /home/suganya/upstream_llvm/build/lib/clang/21/include -internal-isystem /usr/local/include -internal-isystem /usr/lib/gcc/x86_64-linux-gnu/11/../../../../x86_64-linux-gnu/include -internal-externc-isystem /usr/include/x86_64-linux-gnu -internal-externc-isystem /include -internal-externc-isystem /usr/include -fdeprecated-macro -ferror-limit 19 -fopenmp -fgnuc-version=4.2.1 -fskip-odr-check-in-gmf -fcxx-exceptions -fexceptions -fcolor-diagnostics -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /tmp/lambda_iter-1675e7.o -x c++ lambda_iter.cpp
1.      <eof> parser at end of file
2.      Per-file LLVM IR generation
3.      lambda_iter.cpp:58:13: Generating code for declaration 'F<double>::ak(H &)::(anonymous class)::operator()'
 #0 0x00005dfda87f5210 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) 

Example: (Reduced example of SIRIUS library application using creduce)
enum a {};
class b {
public:
  b(int);
};
struct c {
  typedef b h;
};
using e = b;
using f = b;
template <typename> class g {};
template <typename l> class i {
public:
  using j = long;
  l::h aa;
  i(g<l>) : aa{0} {}
 bool operator!=(i);
  void operator++();
  auto operator*() {
    int k;
 return k;
  }
  j operator-(i);
  void operator+=(j);
};
class o : public g<c> {
public:
  using p = int;
  o(p, e, f);
};
auto begin(g<c> ac) {
  i ad(ac);
  return ad;
}
template <typename l> auto end(l ac) {
 i ad(ac);
  return ad;
}
using m = b;
using n = b;
class D {
protected:
  D(int, int, n, m, a);
};
class H : D {
  int af;
  o t;

public:
  a v;
  int q;
  H(n ag, m r) : D(q, 0, ag, r, v), t{o(af, 0, 0)} {}
  auto s() { return t; }
};
template <typename> class F { void ak(H &) const; };
template <typename am> void F<am>::ak(H &an) const {
 auto ao = an.s();
  auto ap = [ao](H) {
#pragma omp for
    for (auto d : ao)
      ;
  };
  H ar(0, 0);
  ap(ar);
}
template class F<double>;

With release llvm binaries, it compiles successfully.
</pre>
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