WIP: fix assert in hasInitWithSideEffects

[hnrklssn]

This fixes another instance of Assertion failed: (NumCurrentElementsDeserializing == 0 && "should not be called while already deserializing"). I ran into it while importing clang modules from Swift, but I haven't been able to reproduce it in a test case yet. The error seems to be that an initializer expression can be deserialized and contain a call to a function whose function body is not yet deserialized. When evaluateValue() is called the constexpr evaluation triggers deserialization of the function body.

rdar://154717930

[llvmbot]

@llvm/pr-subscribers-clang

Author: Henrik G. Olsson (hnrklssn)

Changes

This fixes another instance of Assertion failed: (NumCurrentElementsDeserializing == 0 && "should not be called while already deserializing"). I ran into it while importing clang modules from Swift, but I haven't been able to reproduce it in a test case yet. The error seems to be that an initializer expression can be deserialized and contain a call to a function whose function body is not yet deserialized. When evaluateValue() is called the constexpr evaluation triggers deserialization of the function body.

rdar://154717930

---

Full diff: https://github.com/llvm/llvm-project/pull/146468.diff

1 Files Affected:

• (modified) clang/lib/AST/Decl.cpp (+3-9)

diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 5cdf75d71e4d7..5e91566e87f74 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2444,20 +2444,14 @@ bool VarDecl::hasInitWithSideEffects() const {
   if (!hasInit())
     return false;
 
-  // Check if we can get the initializer without deserializing
-  const Expr *E = nullptr;
+  // Check if we can get the initializer directly without an external source
   if (auto *S = dyn_cast<Stmt *>(Init)) {
-    E = cast<Expr>(S);
-  } else {
-    E = cast_or_null<Expr>(getEvaluatedStmt()->Value.getWithoutDeserializing());
-  }
-
-  if (E)
+    const Expr *E = cast<Expr>(S);
     return E->HasSideEffects(getASTContext()) &&
            // We can get a value-dependent initializer during error recovery.
            (E->isValueDependent() || !evaluateValue());
+  }
 
-  assert(getEvaluatedStmt()->Value.isOffset());
   // ASTReader tracks this without having to deserialize the initializer
   if (auto Source = getASTContext().getExternalSource())
     return Source->hasInitializerWithSideEffects(this);

[ChuanqiXu9]

The change LGTM but I want a test to avoid further regression.

[hnrklssn]

The change LGTM but I want a test to avoid further regression.

Yup, working on it