fix(needless_if): don't expand macro invocations in the suggestion

clippy_lints/src/needless_if.rs

@@ -1,7 +1,7 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::higher::If;
 use clippy_utils::is_from_proc_macro;
-use clippy_utils::source::SpanRangeExt;
+use clippy_utils::source::{SpanRangeExt, walk_span_to_context};
 use rustc_errors::Applicability;
 use rustc_hir::{ExprKind, Stmt, StmtKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
@@ -56,7 +56,8 @@ impl LateLintPass<'_> for NeedlessIf {
                 src.bytes()
                     .all(|ch| matches!(ch, b'{' | b'}') || ch.is_ascii_whitespace())
             })
-            && let Some(cond_snippet) = cond.span.get_source_text(cx)
+            && let Some(cond_span) = walk_span_to_context(cond.span, expr.span.ctxt())
+            && let Some(cond_snippet) = cond_span.get_source_text(cx)
             && !is_from_proc_macro(cx, expr)
         {
             span_lint_and_sugg(

tests/ui/needless_if.fixed

@@ -104,3 +104,12 @@ fn main() {
 
     let () = if maybe_side_effect() {};
 }
+
+fn issue15960() -> i32 {
+    matches!(2, 3);
+    //~^ needless_if
+    matches!(2, 3) == (2 * 2 == 5);
+    //~^ needless_if
+
+    1 // put something here so that `if` is a statement not an expression
+}

tests/ui/needless_if.rs

@@ -105,3 +105,12 @@ fn main() {
 
     let () = if maybe_side_effect() {};
 }
+
+fn issue15960() -> i32 {
+    if matches!(2, 3) {}
+    //~^ needless_if
+    if matches!(2, 3) == (2 * 2 == 5) {}
+    //~^ needless_if
+
+    1 // put something here so that `if` is a statement not an expression
+}

tests/ui/needless_if.stderr

@@ -74,5 +74,17 @@ error: this `if` branch is empty
 LL |     if true {}
    |     ^^^^^^^^^^ help: you can remove it: `true;`
 
-error: aborting due to 7 previous errors
+error: this `if` branch is empty
+  --> tests/ui/needless_if.rs:110:5
+   |
+LL |     if matches!(2, 3) {}
+   |     ^^^^^^^^^^^^^^^^^^^^ help: you can remove it: `matches!(2, 3);`
+
+error: this `if` branch is empty
+  --> tests/ui/needless_if.rs:112:5
+   |
+LL |     if matches!(2, 3) == (2 * 2 == 5) {}
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: you can remove it: `matches!(2, 3) == (2 * 2 == 5);`
+
+error: aborting due to 9 previous errors