let_with_type_underscore:

* Delay macro check.
* Use `is_from_proc_macro

Author: Jarcho

clippy_lints/src/let_with_type_underscore.rs

@@ -1,5 +1,5 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use clippy_utils::source::snippet;
+use clippy_utils::is_from_proc_macro;
 use rustc_hir::{LetStmt, TyKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::lint::in_external_macro;
@@ -25,19 +25,14 @@ declare_clippy_lint! {
 }
 declare_lint_pass!(UnderscoreTyped => [LET_WITH_TYPE_UNDERSCORE]);
 
-impl LateLintPass<'_> for UnderscoreTyped {
-    fn check_local(&mut self, cx: &LateContext<'_>, local: &LetStmt<'_>) {
-        if !in_external_macro(cx.tcx.sess, local.span)
-            && let Some(ty) = local.ty // Ensure that it has a type defined
+impl<'tcx> LateLintPass<'tcx> for UnderscoreTyped {
+    fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx LetStmt<'_>) {
+        if let Some(ty) = local.ty // Ensure that it has a type defined
             && let TyKind::Infer = &ty.kind // that type is '_'
             && local.span.eq_ctxt(ty.span)
+            && !in_external_macro(cx.tcx.sess, local.span)
+            && !is_from_proc_macro(cx, ty)
         {
-            // NOTE: Using `is_from_proc_macro` on `init` will require that it's initialized,
-            // this doesn't. Alternatively, `WithSearchPat` can be implemented for `Ty`
-            if snippet(cx, ty.span, "_").trim() != "_" {
-                return;
-            }
-
             span_lint_and_help(
                 cx,
                 LET_WITH_TYPE_UNDERSCORE,