================
@@ -2535,10 +2535,34 @@ Decl
*TemplateDeclInstantiator::VisitVarTemplatePartialSpecializationDecl(
// Lookup the already-instantiated declaration and return that.
DeclContext::lookup_result Found = Owner->lookup(VarTemplate->getDeclName());
+
+ // Normally the primary member variable template has already been
instantiated
+ // into Owner, because it is declared before its partial specializations and
+ // so is visited first while instantiating the enclosing class. However, when
+ // the class template pattern is deserialized from a module or precompiled
+ // preamble, the primary may not have been materialized into Owner yet,
+ // leaving the lookup empty. Previously this asserted (and crashed release
+ // builds with a null dereference). Instantiate the primary on demand and
look
+ // it up again.
+ if (Found.empty()) {
+ if (Decl *InstPrimary = Visit(VarTemplate))
+ if (auto *InstVTD = dyn_cast<VarTemplateDecl>(InstPrimary))
+ Found = Owner->lookup(InstVTD->getDeclName());
+ }
+
+ // After the on-demand instantiation above the primary must be present. Keep
+ // the original invariant assertions so a genuinely-missing primary is still
+ // flagged in +Asserts builds, with a null return as a release-safe guard so
a
+ // stray case degrades gracefully instead of dereferencing an empty lookup
+ // result.
assert(!Found.empty() && "Instantiation found nothing?");
+ if (Found.empty())
+ return nullptr;
VarTemplateDecl *InstVarTemplate = dyn_cast<VarTemplateDecl>(Found.front());
assert(InstVarTemplate && "Instantiation did not find a variable template?");
+ if (!InstVarTemplate)
+ return nullptr;
----------------
TPPPP72 wrote:
I believe this code lacks human review. I don't understand its meaning. Could
you explain why an if statement is added after `assert`? It seems meaningless
for `assert`.
https://github.com/llvm/llvm-project/pull/202958
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