frontend: warn useless `do` blocks

Signed-off-by: Jean Privat <jean@pryen.org>

diff --git a/src/frontend/simple_misc_analysis.nit b/src/frontend/simple_misc_analysis.nit
index 885d794..f61b10a 100644 (file)
--- a/src/frontend/simple_misc_analysis.nit
+++ b/src/frontend/simple_misc_analysis.nit
@@ -65,6 +65,14 @@ private class SimpleMiscVisitor
        do
                toolcontext.warning(node.hot_location, tag, msg)
        end
+
+       # Issue a warning if `sub` is a standalone `do` block.
+       fun check_do_expr(sub: nullable AExpr)
+       do
+               if sub isa ADoExpr then
+                       warning(sub, "useless-do", "Warning: superfluous `do` block.")
+               end
+       end
 end
 
 
@@ -143,6 +151,21 @@ redef class AWhileExpr
                else
                        n_expr.warn_parentheses(v)
                end
+               v.check_do_expr(n_block)
+       end
+end
+
+redef class ADoExpr
+       redef fun after_simple_misc(v)
+       do
+               v.check_do_expr(n_block)
+       end
+end
+
+redef class ALoopExpr
+       redef fun after_simple_misc(v)
+       do
+               v.check_do_expr(n_block)
        end
 end
 
@@ -150,6 +173,14 @@ redef class AForExpr
        redef fun after_simple_misc(v)
        do
                n_expr.warn_parentheses(v)
+               v.check_do_expr(n_block)
+       end
+end
+
+redef class AWithExpr
+       redef fun after_simple_misc(v)
+       do
+               v.check_do_expr(n_block)
        end
 end