Auto merge of #10911 - lochetti:fix_9657, r=Alexendoo

Don't linting `as_conversions` in proc macros

Don't linting `as_conversions` if code was generated by procedural macro.

This PR fixes rust-lang/rust-clippy#9657

I implemented the fix changing the lint code to be a `LateLintPass` in order to be able to use the `is_from_proc_macro` out of the box. If the reviwer thinks that it would be better to do the other way (implementing `WithSearchPat`) just let me know. I might need some help in implementing it for the `ustc_ast::ast::Expr`

changelog: [`as_conversions`] avoiding warnings in macro-generated code

Author: bors

clippy_lints/src/as_conversions.rs

@@ -1,6 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_help;
-use rustc_ast::ast::{Expr, ExprKind};
-use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
+use clippy_utils::is_from_proc_macro;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 
@@ -45,9 +46,9 @@ declare_clippy_lint! {
 
 declare_lint_pass!(AsConversions => [AS_CONVERSIONS]);
 
-impl EarlyLintPass for AsConversions {
-    fn check_expr(&mut self, cx: &EarlyContext<'_>, expr: &Expr) {
-        if in_external_macro(cx.sess(), expr.span) {
+impl<'tcx> LateLintPass<'tcx> for AsConversions {
+    fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
+        if in_external_macro(cx.sess(), expr.span) || is_from_proc_macro(cx, expr) {
             return;
         }
 

clippy_lints/src/lib.rs

@@ -850,7 +850,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(move |_| Box::new(large_stack_arrays::LargeStackArrays::new(array_size_threshold)));
     store.register_late_pass(move |_| Box::new(large_const_arrays::LargeConstArrays::new(array_size_threshold)));
     store.register_late_pass(|_| Box::new(floating_point_arithmetic::FloatingPointArithmetic));
-    store.register_early_pass(|| Box::new(as_conversions::AsConversions));
+    store.register_late_pass(|_| Box::new(as_conversions::AsConversions));
     store.register_late_pass(|_| Box::new(let_underscore::LetUnderscore));
     store.register_early_pass(|| Box::<single_component_path_imports::SingleComponentPathImports>::default());
     let max_fn_params_bools = conf.max_fn_params_bools;

tests/ui/as_conversions.rs

@@ -1,10 +1,11 @@
 //@aux-build:proc_macros.rs
 
 #![warn(clippy::as_conversions)]
-#![allow(clippy::borrow_as_ptr)]
+#![allow(clippy::borrow_as_ptr, unused)]
 
 extern crate proc_macros;
 use proc_macros::external;
+use proc_macros::with_span;
 
 fn main() {
     let i = 0u32 as u64;
@@ -13,3 +14,11 @@ fn main() {
 
     external!(0u32 as u64);
 }
+
+with_span!(
+    span
+
+    fn coverting() {
+        let x = 0u32 as u64;
+    }
+);

tests/ui/as_conversions.stderr

@@ -1,5 +1,5 @@
 error: using a potentially dangerous silent `as` conversion
-  --> $DIR/as_conversions.rs:10:13
+  --> $DIR/as_conversions.rs:11:13
    |
 LL |     let i = 0u32 as u64;
    |             ^^^^^^^^^^^
@@ -8,15 +8,15 @@ LL |     let i = 0u32 as u64;
    = note: `-D clippy::as-conversions` implied by `-D warnings`
 
 error: using a potentially dangerous silent `as` conversion
-  --> $DIR/as_conversions.rs:12:13
+  --> $DIR/as_conversions.rs:13:13
    |
 LL |     let j = &i as *const u64 as *mut u64;
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider using a safe wrapper for this conversion
 
 error: using a potentially dangerous silent `as` conversion
-  --> $DIR/as_conversions.rs:12:13
+  --> $DIR/as_conversions.rs:13:13
    |
 LL |     let j = &i as *const u64 as *mut u64;
    |             ^^^^^^^^^^^^^^^^