Auto merge of #4113 - rust-lang:author, r=flip1995

Fix `Block`  dump in author lint

changelog: The `#[clippy::author]` attribute now emits correct pattern code for block expressions

Author: bors

clippy_lints/src/utils/author.rs

@@ -4,7 +4,7 @@
 use crate::utils::{get_attr, higher};
 use rustc::hir;
 use rustc::hir::intravisit::{NestedVisitorMap, Visitor};
-use rustc::hir::{BindingAnnotation, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
+use rustc::hir::{BindingAnnotation, Block, Expr, ExprKind, Pat, PatKind, QPath, Stmt, StmtKind, TyKind};
 use rustc::lint::{LateContext, LateLintPass, LintArray, LintContext, LintPass};
 use rustc::session::Session;
 use rustc::{declare_lint_pass, declare_tool_lint};
@@ -511,6 +511,17 @@ impl<'tcx> Visitor<'tcx> for PrintVisitor {
         }
     }
 
+    fn visit_block(&mut self, block: &Block) {
+        let trailing_pat = self.next("trailing_expr");
+        println!("    if let Some({}) = &{}.expr;", trailing_pat, self.current);
+        println!("    if {}.stmts.len() == {};", self.current, block.stmts.len());
+        let current = self.current.clone();
+        for (i, stmt) in block.stmts.iter().enumerate() {
+            self.current = format!("{}.stmts[{}]", current, i);
+            self.visit_stmt(stmt);
+        }
+    }
+
     #[allow(clippy::too_many_lines)]
     fn visit_pat(&mut self, pat: &Pat) {
         print!("    if let PatKind::");

tests/ui/author/blocks.rs

@@ -0,0 +1,15 @@
+#![feature(stmt_expr_attributes)]
+
+#[rustfmt::skip]
+fn main() {
+    #[clippy::author]
+    {
+        ;;;;
+    }
+}
+
+#[clippy::author]
+fn foo() {
+    let x = 42i32;
+    -x;
+}

tests/ui/author/blocks.stderr

@@ -0,0 +1,10 @@
+error: statement with no effect
+  --> $DIR/blocks.rs:14:5
+   |
+LL |     -x;
+   |     ^^^
+   |
+   = note: `-D clippy::no-effect` implied by `-D warnings`
+
+error: aborting due to previous error
+

tests/ui/author/blocks.stdout

@@ -0,0 +1,13 @@
+if_chain! {
+    if let ExprKind::Block(ref block) = expr.node;
+    if let Some(trailing_expr) = &block.expr;
+    if block.stmts.len() == 0;
+    then {
+        // report your lint here
+    }
+}
+if_chain! {
+    then {
+        // report your lint here
+    }
+}

tests/ui/author/for_loop.stdout

@@ -11,10 +11,12 @@ if_chain! {
     // unimplemented: field checks
     if arms.len() == 1;
     if let ExprKind::Loop(ref body, ref label, LoopSource::ForLoop) = arms[0].body.node;
-    if let StmtKind::Local(ref local) = body.node;
+    if let Some(trailing_expr) = &body.expr;
+    if body.stmts.len() == 4;
+    if let StmtKind::Local(ref local) = body.stmts[0].node;
     if let PatKind::Binding(BindingAnnotation::Mutable, _, name, None) = local.pat.node;
     if name.node.as_str() == "__next";
-    if let StmtKind::Expr(ref e, _) = local.pat.node
+    if let StmtKind::Expr(ref e, _) = body.stmts[1].node
     if let ExprKind::Match(ref expr2, ref arms1, MatchSource::ForLoopDesugar) = e.node;
     if let ExprKind::Call(ref func1, ref args1) = expr2.node;
     if let ExprKind::Path(ref path2) = func1.node;
@@ -38,15 +40,17 @@ if_chain! {
     if arms1[1].pats.len() == 1;
     if let PatKind::Path(ref path7) = arms1[1].pats[0].node;
     if match_qpath(path7, &["{{root}}", "std", "option", "Option", "None"]);
-    if let StmtKind::Local(ref local1) = path7.node;
+    if let StmtKind::Local(ref local1) = body.stmts[2].node;
     if let Some(ref init) = local1.init;
     if let ExprKind::Path(ref path8) = init.node;
     if match_qpath(path8, &["__next"]);
     if let PatKind::Binding(BindingAnnotation::Unannotated, _, name1, None) = local1.pat.node;
     if name1.node.as_str() == "y";
-    if let StmtKind::Expr(ref e1, _) = local1.pat.node
+    if let StmtKind::Expr(ref e1, _) = body.stmts[3].node
     if let ExprKind::Block(ref block) = e1.node;
-    if let StmtKind::Local(ref local2) = block.node;
+    if let Some(trailing_expr1) = &block.expr;
+    if block.stmts.len() == 1;
+    if let StmtKind::Local(ref local2) = block.stmts[0].node;
     if let Some(ref init1) = local2.init;
     if let ExprKind::Path(ref path9) = init1.node;
     if match_qpath(path9, &["y"]);

tests/ui/author/if.stdout

@@ -3,7 +3,9 @@ if_chain! {
     if let Some(ref init) = local.init;
     if let Some((ref cond, ref then, Some(else_))) = higher::if_block(&init);
     if let ExprKind::Block(ref block) = else_.node;
-    if let StmtKind::Semi(ref e, _) = block.node
+    if let Some(trailing_expr) = &block.expr;
+    if block.stmts.len() == 1;
+    if let StmtKind::Semi(ref e, _) = block.stmts[0].node
     if let ExprKind::Binary(ref op, ref left, ref right) = e.node;
     if BinOpKind::Eq == op.node;
     if let ExprKind::Lit(ref lit) = left.node;
@@ -13,7 +15,9 @@ if_chain! {
     if let ExprKind::Lit(ref lit2) = cond.node;
     if let LitKind::Bool(true) = lit2.node;
     if let ExprKind::Block(ref block1) = then.node;
-    if let StmtKind::Semi(ref e1, _) = block1.node
+    if let Some(trailing_expr1) = &block1.expr;
+    if block1.stmts.len() == 1;
+    if let StmtKind::Semi(ref e1, _) = block1.stmts[0].node
     if let ExprKind::Binary(ref op1, ref left1, ref right1) = e1.node;
     if BinOpKind::Eq == op1.node;
     if let ExprKind::Lit(ref lit3) = left1.node;