Auto merge of #12624 - J-ZhengLi:issue12586, r=xFrednet

fix [`large_stack_arrays`] linting in `vec` macro

fixes: #12586

this PR also adds a wrapper function `matching_root_macro_call` to `clippy_utils::macros`, considering how often that same pattern appears in the codebase.

(I'm always very indecisive towards naming, so, if anyone have better idea of how that function should be named, feel free to suggest it)

---

changelog: fix [`large_stack_arrays`] linting in `vec` macro; add `matching_root_macro_call` to clippy_utils

clippy_utils/src/macros.rs

@@ -119,10 +119,20 @@ pub fn macro_backtrace(span: Span) -> impl Iterator<Item = MacroCall> {
 
 /// If the macro backtrace of `span` has a macro call at the root expansion
 /// (i.e. not a nested macro call), returns `Some` with the `MacroCall`
+///
+/// If you only want to check whether the root macro has a specific name,
+/// consider using [`matching_root_macro_call`] instead.
 pub fn root_macro_call(span: Span) -> Option<MacroCall> {
     macro_backtrace(span).last()
 }
 
+/// A combination of [`root_macro_call`] and
+/// [`is_diagnostic_item`](rustc_middle::ty::TyCtxt::is_diagnostic_item) that returns a `MacroCall`
+/// at the root expansion if only it matches the given name.
+pub fn matching_root_macro_call(cx: &LateContext<'_>, span: Span, name: Symbol) -> Option<MacroCall> {
+    root_macro_call(span).filter(|mc| cx.tcx.is_diagnostic_item(name, mc.def_id))
+}
+
 /// Like [`root_macro_call`], but only returns `Some` if `node` is the "first node"
 /// produced by the macro call, as in [`first_node_in_macro`].
 pub fn root_macro_call_first_node(cx: &LateContext<'_>, node: &impl HirNode) -> Option<MacroCall> {