fix: large_stack_frames FP on compiler generated targets

Author: profetia

clippy_lints/src/large_stack_frames.rs

@@ -170,6 +170,11 @@ impl<'tcx> LateLintPass<'tcx> for LargeStackFrames {
                 FnKind::Closure => entire_fn_span,
             };
 
+            // Don't lint compiler-generated targets
+            if fn_span.is_dummy() {
+                return;
+            }
+
             span_lint_and_then(
                 cx,
                 LARGE_STACK_FRAMES,

tests/ui-toml/large_stack_frames_for_generated_fn/clippy.toml

@@ -0,0 +1 @@
+stack-size-threshold = 0

tests/ui-toml/large_stack_frames_for_generated_fn/large_stack_frames.rs

@@ -0,0 +1,15 @@
+//@compile-flags: --test
+#![allow(unused)]
+#![warn(clippy::large_stack_frames)]
+
+fn main() {
+    //~^ large_stack_frames
+    println!("Hello, world!");
+}
+
+#[cfg(test)]
+#[allow(clippy::large_stack_frames)]
+mod test {
+    #[test]
+    fn main_test() {}
+}

tests/ui-toml/large_stack_frames_for_generated_fn/large_stack_frames.stderr

@@ -0,0 +1,16 @@
+error: this function may allocate 88 bytes on the stack
+  --> tests/ui-toml/large_stack_frames_for_generated_fn/large_stack_frames.rs:5:4
+   |
+LL | fn main() {
+   |    ^^^^
+LL |
+LL |     println!("Hello, world!");
+   |     ------------------------- this is the largest part, at 48 bytes for type `std::fmt::Arguments<'_>`
+   |
+   = note: 88 bytes is larger than Clippy's configured `stack-size-threshold` of 0
+   = note: allocating large amounts of stack space can overflow the stack and cause the program to abort
+   = note: `-D clippy::large-stack-frames` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::large_stack_frames)]`
+
+error: aborting due to 1 previous error
+