[clang] [llvm] [mlir] [LLVM][MLIR] Treewide C++26/2d fixes (PR #223284)

[via llvm-commits]

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@@ -512,9 +512,7 @@ class OpenMPIRBuilder {
 public:
   /// Create a new OpenMPIRBuilder operating on the given module \p M. This will
   /// not have an effect on \p M (see initialize)
-  OpenMPIRBuilder(Module &M)
-      : M(M), Builder(M.getContext()), OffloadInfoManager(this),
-        T(M.getTargetTriple()), IsFinalized(false) {}
+  LLVM_ABI OpenMPIRBuilder(Module &M);
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rdong8 wrote:

outlined into the implementation file since this class holds `forward_list<CanonicalLoopInfo>` but `CanonicalLoopInfo` is forward declared, so the new constexpr ctor tries to construct the incomplete type.

https://godbolt.org/z/f5ejxnjYT

https://github.com/llvm/llvm-project/pull/223284