Add smarter macro check for block_in_if (fixes #528)

src/block_in_if_condition.rs

@@ -79,13 +79,18 @@ impl LateLintPass for BlockInIfCondition {
                         if let Some(ref ex) = block.expr {
                             // don't dig into the expression here, just suggest that they remove
                             // the block
-
+                            if differing_macro_contexts(expr.span, ex.span) {
+                                return;
+                            }
                             span_help_and_lint(cx, BLOCK_IN_IF_CONDITION_EXPR, check.span,
                                 BRACED_EXPR_MESSAGE,
                                 &format!("try\nif {} {} ... ", snippet_block(cx, ex.span, ".."),
                                 snippet_block(cx, then.span, "..")));
                         }
                     } else {
+                        if differing_macro_contexts(expr.span, block.stmts[0].span) {
+                            return;
+                        }
                         // move block higher
                         span_help_and_lint(cx, BLOCK_IN_IF_CONDITION_STMT, check.span,
                             COMPLEX_BLOCK_MESSAGE,

src/utils.rs

@@ -74,6 +74,10 @@ macro_rules! if_let_chain {
     };
 }
 
+/// Returns true if the two spans come from differing expansions (i.e. one is from a macro and one isn't)
+pub fn differing_macro_contexts(sp1: Span, sp2: Span) -> bool {
+    sp1.expn_id != sp2.expn_id
+}
 /// returns true if this expn_info was expanded by any macro
 pub fn in_macro<T: LintContext>(cx: &T, span: Span) -> bool {
     cx.sess().codemap().with_expn_info(span.expn_id,

tests/compile-fail/block_in_if_condition.rs

@@ -5,6 +5,15 @@
 #![deny(block_in_if_condition_stmt)]
 #![allow(unused)]
 
+
+macro_rules! blocky {
+    () => {{true}}
+}
+
+fn macro_if() {
+    if blocky!() {
+    }
+}
 fn condition_has_block() -> i32 {
 
     if { //~ERROR in an 'if' condition, avoid complex blocks or closures with blocks; instead, move the block or closure higher and bind it with a 'let'