[clang] [clang-tools-extra] [Clang][AST] Introduce `ExplicitInstantiationDecl` to preserve source info and fix diagnostic locations (PR #191658)

[via cfe-commits]

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@@ -2101,6 +2101,14 @@ Decl *TemplateDeclInstantiator::VisitStaticAssertDecl(StaticAssertDecl *D) {
       InstantiatedMessageExpr.get(), D->getRParenLoc(), D->isFailed());
 }
 
+Decl *TemplateDeclInstantiator::VisitExplicitInstantiationDecl(
+    ExplicitInstantiationDecl *D) {
+  // ExplicitInstantiationDecl is a source-info-only node and should not
+  // appear inside a template pattern. Nothing to instantiate.
+  llvm_unreachable("ExplicitInstantiationDecl should not be instantiated");
+  return nullptr;
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16bit-ykiko wrote:

Fixed.

https://github.com/llvm/llvm-project/pull/191658