fix: don't lint on if cfg!(..) { panic!(..) }

Author: ada4a

clippy_lints/src/manual_assert.rs

@@ -7,6 +7,7 @@ use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::declare_lint_pass;
+use rustc_span::sym;
 
 declare_clippy_lint! {
     /// ### What it does
@@ -39,6 +40,8 @@ impl<'tcx> LateLintPass<'tcx> for ManualAssert {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
         if let Some(higher::If { cond, then, r#else: None }) = higher::If::hir(expr)
             && !matches!(cond.kind, ExprKind::Let(_))
+            // Don't lint on `if cfg!(..) { panic!(..) }
+            && root_macro_call(cond.span).is_none_or(|macro_call| cx.tcx.item_name(macro_call.def_id) != sym::cfg)
             && !expr.span.from_expansion()
             && let then = peel_blocks_with_stmt(then)
             && let Some(macro_call) = root_macro_call(then.span)

tests/ui/manual_assert.edition2018.stderr

@@ -190,7 +190,25 @@ LL +         const BAR: () = assert!(N != 0, );
    |
 
 error: only a `panic!` in `if`-then statement
-  --> tests/ui/manual_assert.rs:116:5
+  --> tests/ui/manual_assert.rs:119:5
+   |
+LL | /     if foo!() {
+LL | |
+LL | |         panic!("not a `cfg`, so lint")
+LL | |     }
+   | |_____^
+   |
+help: try instead
+   |
+LL -     if foo!() {
+LL -
+LL -         panic!("not a `cfg`, so lint")
+LL -     }
+LL +     assert!(!foo!(), "not a `cfg`, so lint")
+   |
+
+error: only a `panic!` in `if`-then statement
+  --> tests/ui/manual_assert.rs:132:5
    |
 LL | /     if !is_x86_feature_detected!("ssse3") {
 LL | |
@@ -207,5 +225,5 @@ LL -     }
 LL +     assert!(is_x86_feature_detected!("ssse3"), "SSSE3 is not supported");
    |
 
-error: aborting due to 11 previous errors
+error: aborting due to 12 previous errors
 

tests/ui/manual_assert.edition2021.stderr

@@ -190,7 +190,25 @@ LL +         const BAR: () = assert!(N != 0, );
    |
 
 error: only a `panic!` in `if`-then statement
-  --> tests/ui/manual_assert.rs:116:5
+  --> tests/ui/manual_assert.rs:119:5
+   |
+LL | /     if foo!() {
+LL | |
+LL | |         panic!("not a `cfg`, so lint")
+LL | |     }
+   | |_____^
+   |
+help: try instead
+   |
+LL -     if foo!() {
+LL -
+LL -         panic!("not a `cfg`, so lint")
+LL -     }
+LL +     assert!(!foo!(), "not a `cfg`, so lint")
+   |
+
+error: only a `panic!` in `if`-then statement
+  --> tests/ui/manual_assert.rs:132:5
    |
 LL | /     if !is_x86_feature_detected!("ssse3") {
 LL | |
@@ -207,5 +225,5 @@ LL -     }
 LL +     assert!(is_x86_feature_detected!("ssse3"), "SSSE3 is not supported");
    |
 
-error: aborting due to 11 previous errors
+error: aborting due to 12 previous errors
 

tests/ui/manual_assert.rs

@@ -106,6 +106,22 @@ fn issue12505() {
     }
 }
 
+fn issue13883() {
+    if cfg!(debug_assertions) {
+        panic!("foobar")
+    }
+
+    macro_rules! foo {
+        () => {
+            true
+        };
+    }
+    if foo!() {
+        //~^ manual_assert
+        panic!("not a `cfg`, so lint")
+    }
+}
+
 fn issue15227(left: u64, right: u64) -> u64 {
     macro_rules! is_x86_feature_detected {
         ($feature:literal) => {