1 files changed, 16 insertions, 20 deletions
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 69b793b..8ae1baa 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -3249,26 +3249,6 @@ static void mergeParamDeclAttributes(ParmVarDecl *newDecl,
            diag::note_carries_dependency_missing_first_decl) << 1/*Param*/;
   }
 
-  // HLSL parameter declarations for inout and out must match between
-  // declarations. In HLSL inout and out are ambiguous at the call site, but
-  // have different calling behavior, so you cannot overload a method based on a
-  // difference between inout and out annotations.
-  if (S.getLangOpts().HLSL) {
-    const auto *NDAttr = newDecl->getAttr<HLSLParamModifierAttr>();
-    const auto *ODAttr = oldDecl->getAttr<HLSLParamModifierAttr>();
-    // We don't need to cover the case where one declaration doesn't have an
-    // attribute. The only possible case there is if one declaration has an `in`
-    // attribute and the other declaration has no attribute. This case is
-    // allowed since parameters are `in` by default.
-    if (NDAttr && ODAttr &&
-        NDAttr->getSpellingListIndex() != ODAttr->getSpellingListIndex()) {
-      S.Diag(newDecl->getLocation(), diag::err_hlsl_param_qualifier_mismatch)
-          << NDAttr << newDecl;
-      S.Diag(oldDecl->getLocation(), diag::note_previous_declaration_as)
-          << ODAttr;
-    }
-  }
-
   if (!oldDecl->hasAttrs())
     return;
 
@@ -4054,6 +4034,22 @@ bool Sema::MergeFunctionDecl(FunctionDecl *New, NamedDecl *&OldD, Scope *S,
       }
     }
 
+    // HLSL check parameters for matching ABI specifications.
+    if (getLangOpts().HLSL) {
+      if (HLSL().CheckCompatibleParameterABI(New, Old))
+        return true;
+
+      // If no errors are generated when checking parameter ABIs we can check if
+      // the two declarations have the same type ignoring the ABIs and if so,
+      // the declarations can be merged. This case for merging is only valid in
+      // HLSL because there are no valid cases of merging mismatched parameter
+      // ABIs except the HLSL implicit in and explicit in.
+      if (Context.hasSameFunctionTypeIgnoringParamABI(OldQTypeForComparison,
+                                                      NewQType))
+        return MergeCompatibleFunctionDecls(New, Old, S, MergeTypeWithOld);
+      // Fall through for conflicting redeclarations and redefinitions.
+    }
+
     // If the function types are compatible, merge the declarations. Ignore the
     // exception specifier because it was already checked above in
     // CheckEquivalentExceptionSpec, and we don't want follow-on diagnostics