Auto merge of #7789 - flip1995:double_semi_if_nothing_returned, r=camsteffen

Don't trigger semicolon_if_nothing_returned in expanded code

Fixes #7768

Before, this lint didn't trigger on macros. With rust-lang/rust#88175
this isn't enough anymore. In this PR a `WhileLoop` desugaring kind was
introduced. This overrides the span of expanded expressions when
lowering the while loop. So if a while loop is in a macro, the
expressions that it expands to are no longer marked with
`ExpnKind::Macro`, but with `ExpnKind::Desugaring`. In general, this is
the correct behavior and the same that is done for `ForLoop`s. It just
tripped up this lint.

r? `@camsteffen`

changelog: [`semicolon_if_nothing_returned`]: Fix regression on macros containing while loops

clippy_lints/src/semicolon_if_nothing_returned.rs

@@ -1,7 +1,7 @@
 use crate::rustc_lint::LintContext;
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_macro_callsite;
-use clippy_utils::{in_macro, sugg};
+use clippy_utils::sugg;
 use if_chain::if_chain;
 use rustc_errors::Applicability;
 use rustc_hir::{Block, ExprKind};
@@ -39,7 +39,7 @@
 impl LateLintPass<'_> for SemicolonIfNothingReturned {
     fn check_block(&mut self, cx: &LateContext<'tcx>, block: &'tcx Block<'tcx>) {
         if_chain! {
-            if !in_macro(block.span);
+            if !block.span.from_expansion();
             if let Some(expr) = block.expr;
             let t_expr = cx.typeck_results().expr_ty(expr);
             if t_expr.is_unit();

tests/ui/semicolon_if_nothing_returned.rs

@@ -98,3 +98,15 @@ fn unsafe_checks() {
     let mut s = MaybeUninit::<String>::uninit();
     let _d = || unsafe { ptr::drop_in_place(s.as_mut_ptr()) };
 }
+
+// Issue #7768
+#[rustfmt::skip]
+fn macro_with_semicolon() {
+    macro_rules! repro {
+        () => {
+            while false {
+            }
+        };
+    }
+    repro!();
+}