Use new util function in suspicious_else_formatting

clippy_lints/src/formatting.rs

@@ -1,4 +1,5 @@
 use clippy_utils::diagnostics::{span_lint_and_help, span_lint_and_note};
+use clippy_utils::is_span_if;
 use clippy_utils::source::snippet_opt;
 use if_chain::if_chain;
 use rustc_ast::ast::{BinOpKind, Block, Expr, ExprKind, StmtKind, UnOp};
@@ -297,12 +298,11 @@ fn check_array(cx: &EarlyContext<'_>, expr: &Expr) {
 fn check_missing_else(cx: &EarlyContext<'_>, first: &Expr, second: &Expr) {
     if_chain! {
         if !first.span.from_expansion() && !second.span.from_expansion();
-        if let ExprKind::If(cond_expr, ..) = &first.kind;
+        if matches!(first.kind, ExprKind::If(..));
         if is_block(second) || is_if(second);
 
         // Proc-macros can give weird spans. Make sure this is actually an `if`.
-        if let Some(if_snip) = snippet_opt(cx, first.span.until(cond_expr.span));
-        if if_snip.starts_with("if");
+        if is_span_if(cx, first.span);
 
         // If there is a line break between the two expressions, don't lint.
         // If there is a non-whitespace character, this span came from a proc-macro.

clippy_utils/src/check_proc_macro.rs

@@ -162,6 +162,11 @@ pub fn is_expr_from_proc_macro(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
 }
 
 /// Checks if the span actually refers to a match expression
-pub fn is_span_match(cx: &LateContext<'_>, span: Span) -> bool {
+pub fn is_span_match(cx: &impl LintContext, span: Span) -> bool {
     span_matches_pat(cx.sess(), span, Pat::Str("match"), Pat::Str("}"))
 }
+
+/// Checks if the span actually refers to an if expression
+pub fn is_span_if(cx: &impl LintContext, span: Span) -> bool {
+    span_matches_pat(cx.sess(), span, Pat::Str("if"), Pat::Str("}"))
+}

clippy_utils/src/lib.rs

@@ -59,7 +59,7 @@ pub mod usage;
 pub mod visitors;
 
 pub use self::attrs::*;
-pub use self::check_proc_macro::{is_expr_from_proc_macro, is_span_match};
+pub use self::check_proc_macro::{is_expr_from_proc_macro, is_span_if, is_span_match};
 pub use self::hir_utils::{
     both, count_eq, eq_expr_value, hash_expr, hash_stmt, over, HirEqInterExpr, SpanlessEq, SpanlessHash,
 };