[clang] [analyzer][NFC] Explain why operator new/delete should never be eval-called (PR #161370)

[Arseniy Zaostrovnykh via cfe-commits]

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@@ -909,7 +909,13 @@ void ExprEngine::VisitCXXNewAllocatorCall(const CXXNewExpr *CNE,
   ExplodedNodeSet DstPostCall;
   StmtNodeBuilder CallBldr(DstPreCall, DstPostCall, *currBldrCtx);
   for (ExplodedNode *I : DstPreCall) {
-    // FIXME: Provide evalCall for checkers?
+    // Operator new calls (CXXNewExpr) are intentionally not eval-called,
+    // because it does not make sense to eval-call user-provided functions.
+    // 1) If the new operator can be inlined, then don't prevent it from
+    //    inlining by having an eval-call of that operator.
+    // 2) If it can't be inlined, then the default conservative modeling
+    //    is what we want anyway.
+    // So the best is to not allow eval-calling CXXNewExprs from checkers.
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necto wrote:

Perhaps also suggest to do a PreCall or PostCall for the bookkeeping the user has in mind?

https://github.com/llvm/llvm-project/pull/161370