if_let_chain: rename to if_chain, allow mixing if-lets with normal ifs

Author: birkenfeld

src/returns.rs

@@ -67,19 +67,18 @@ impl ReturnPass {
     // Check for "let x = EXPR; x"
     fn check_let_return(&mut self, cx: &Context, block: &Block) {
         // we need both a let-binding stmt and an expr
-        if_let_chain! {
+        if_chain! {
             [
-                Some(stmt) = block.stmts.last(),
-                StmtDecl(ref decl, _) = stmt.node,
-                DeclLocal(ref local) = decl.node,
-                Some(ref initexpr) = local.init,
-                PatIdent(_, Spanned { node: id, .. }, _) = local.pat.node,
-                Some(ref retexpr) = block.expr,
-                ExprPath(_, ref path) = retexpr.node
+                let Some(stmt) = block.stmts.last(),
+                let StmtDecl(ref decl, _) = stmt.node,
+                let DeclLocal(ref local) = decl.node,
+                let Some(ref initexpr) = local.init,
+                let PatIdent(_, Spanned { node: id, .. }, _) = local.pat.node,
+                let Some(ref retexpr) = block.expr,
+                let ExprPath(_, ref path) = retexpr.node,
+                match_path(path, &[&*id.name.as_str()])
             ], {
-                if match_path(path, &[&*id.name.as_str()]) {
-                    self.emit_let_lint(cx, retexpr.span, initexpr.span);
-                }
+                self.emit_let_lint(cx, retexpr.span, initexpr.span);
             }
         }
     }

src/utils.rs

@@ -95,7 +95,7 @@ pub fn walk_ptrs_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
 
 /// Produce a nested chain of if-lets from the patterns:
 ///
-///     if_let_chain! {[Some(y) = x, Some(z) = y],
+///     if_chain! {[Some(y) = x, Some(z) = y],
 ///         {
 ///             block
 ///         }
@@ -109,15 +109,25 @@ pub fn walk_ptrs_ty<'t>(ty: ty::Ty<'t>) -> ty::Ty<'t> {
 ///         }
 ///     }
 #[macro_export]
-macro_rules! if_let_chain {
-    ([$pat:pat = $expr:expr, $($p2:pat = $e2:expr),+], $block:block) => {
+macro_rules! if_chain {
+    ([let $pat:pat = $expr:expr, $($tt:tt)+], $block:block) => {
         if let $pat = $expr {
-           if_let_chain!{ [$($p2 = $e2),+], $block }
+           if_chain!{ [$($tt)+], $block }
         }
     };
-    ([$pat:pat = $expr:expr], $block:block) => {
+    ([let $pat:pat = $expr:expr], $block:block) => {
         if let $pat = $expr {
            $block
         }
     };
+    ([$expr:expr, $($tt:tt)+], $block:block) => {
+        if $expr {
+           if_chain!{ [$($tt)+], $block }
+        }
+    };
+    ([$expr:expr], $block:block) => {
+        if $expr {
+           $block
+        }
+    };
 }