Fix some suggestions of the for-loops-over-fallibles lint

compiler/rustc_lint/src/for_loops_over_fallibles.rs

@@ -49,6 +49,11 @@ impl<'tcx> LateLintPass<'tcx> for ForLoopsOverFallibles {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         let Some((pat, arg)) = extract_for_loop(expr) else { return };
 
+        // Do not put suggestions for external macros.
+        if pat.span.from_expansion() {
+            return;
+        }
+
         let arg_span = arg.span.source_callsite();
 
         let ty = cx.typeck_results().expr_ty(arg);
@@ -77,6 +82,8 @@ impl<'tcx> LateLintPass<'tcx> for ForLoopsOverFallibles {
         };
 
         let sub = if let Some(recv) = extract_iterator_next_call(cx, arg)
+            && recv.span.can_be_used_for_suggestions()
+            && recv.span.between(arg_span.shrink_to_hi()).can_be_used_for_suggestions()
             && let Ok(recv_snip) = cx.sess().source_map().span_to_snippet(recv.span)
         {
             ForLoopsOverFalliblesLoopSub::RemoveNext {

tests/ui/lint/for-loops-over-fallibles/auxiliary/external-macro-issue-148114.rs

@@ -0,0 +1,13 @@
+#[macro_export]
+macro_rules! identity {
+    ($x:ident) => {
+        $x
+    };
+}
+
+#[macro_export]
+macro_rules! do_loop {
+    ($x:ident) => {
+        for $crate::identity!($x) in $x {}
+    };
+}

tests/ui/lint/for-loops-over-fallibles/external-macro-issue-148114.rs

@@ -0,0 +1,14 @@
+//@ check-pass
+//@ aux-build:external-macro-issue-148114.rs
+
+// This test ensures we do not trigger the lint on external macros
+// ref. <https://github.com/rust-lang/rust/issues/148114>
+
+#![deny(for_loops_over_fallibles)]
+
+extern crate external_macro_issue_148114 as dep;
+
+fn main() {
+    let _name = Some(1);
+    dep::do_loop!(_name);
+}

tests/ui/lint/for-loops-over-fallibles/macro-iterator-next.rs

@@ -0,0 +1,21 @@
+// This test ensures that the `for-loops-over-fallibles` lint doesn't suggest
+// removing `next`.
+// ref. <https://github.com/rust-lang/rust-clippy/issues/16133>
+
+#![forbid(for_loops_over_fallibles)]
+//~^ NOTE: the lint level is defined here
+
+fn main() {
+    macro_rules! mac {
+        (next $e:expr) => {
+            $e.iter().next()
+        };
+    }
+
+    for _ in mac!(next [1, 2]) {}
+    //~^ ERROR: for loop over an `Option`. This is more readably written as an `if let` statement
+    //~| NOTE: in this expansion of desugaring of `for` loop
+    //~| NOTE: in this expansion of desugaring of `for` loop
+    //~| HELP: to check pattern in a loop use `while let`
+    //~| HELP: consider using `if let` to clear intent
+}

tests/ui/lint/for-loops-over-fallibles/macro-iterator-next.stderr

@@ -0,0 +1,24 @@
+error: for loop over an `Option`. This is more readably written as an `if let` statement
+  --> $DIR/macro-iterator-next.rs:15:14
+   |
+LL |     for _ in mac!(next [1, 2]) {}
+   |              ^^^^^^^^^^^^^^^^^
+   |
+note: the lint level is defined here
+  --> $DIR/macro-iterator-next.rs:5:11
+   |
+LL | #![forbid(for_loops_over_fallibles)]
+   |           ^^^^^^^^^^^^^^^^^^^^^^^^
+help: to check pattern in a loop use `while let`
+   |
+LL -     for _ in mac!(next [1, 2]) {}
+LL +     while let Some(_) = mac!(next [1, 2]) {}
+   |
+help: consider using `if let` to clear intent
+   |
+LL -     for _ in mac!(next [1, 2]) {}
+LL +     if let Some(_) = mac!(next [1, 2]) {}
+   |
+
+error: aborting due to 1 previous error
+