Fix erroneous error claiming variable is being used before its declaration (#2958)

* Simplify type of diagnoseImpl

* Show source line for Note diagnostics, opting out of this where appropriate

* Make declared after use diagnostic clearer

* Fix erroneous error claiming variable is being used before its declaration

Closes https://github.com/shader-slang/slang/issues/2936

* Fix build on msvc

---------

Co-authored-by: jsmall-nvidia <jsmall@nvidia.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/source/slang/slang-ast-decl.cpp b/source/slang/slang-ast-decl.cpp
index 261378b9a..2f1c7c47e 100644
--- a/source/slang/slang-ast-decl.cpp
+++ b/source/slang/slang-ast-decl.cpp
@@ -102,4 +102,20 @@ void ContainerDecl::buildMemberDictionary()
     SLANG_ASSERT(isMemberDictionaryValid());
 }
 
+bool isLocalVar(const Decl* decl)
+{
+    const auto varDecl = as<VarDecl>(decl);
+    if(!varDecl)
+        return false;
+    const Decl* pp = varDecl->parentDecl;
+    if(as<ScopeDecl>(pp))
+        return true;
+    while(auto genericDecl = as<GenericDecl>(pp))
+        pp = genericDecl->inner;
+    if(as<FunctionDeclBase>(pp))
+        return true;
+
+    return false;
+}
+
 } // namespace Slang