From c514f0b67237ced4f1e6d88044c433a8a6f070b6 Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 18 Mar 2020 16:07:52 +0100
Subject: [PATCH] cgen: automatic dereference and match fix

---
 vlib/v/ast/ast.v         | 18 +++++++++---------
 vlib/v/checker/checker.v |  3 ++-
 vlib/v/gen/cgen.v        | 13 +++++++++----
 3 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/vlib/v/ast/ast.v b/vlib/v/ast/ast.v
index 660312ba2d..f1378280e6 100644
--- a/vlib/v/ast/ast.v
+++ b/vlib/v/ast/ast.v
@@ -347,16 +347,16 @@ mut:
 
 pub struct MatchExpr {
 pub:
-	tok_kind    token.Kind
-	cond        Expr
-	branches    []MatchBranch
-	pos         token.Position
+	tok_kind      token.Kind
+	cond          Expr
+	branches      []MatchBranch
+	pos           token.Position
 mut:
-	is_expr     bool // returns a value
-	return_type table.Type
-	cond_type   table.Type // type of `x` in `match x {`
-	// expected_type table.Type // for debugging only
-	is_sum_type bool
+	is_expr       bool // returns a value
+	return_type   table.Type
+	cond_type     table.Type // type of `x` in `match x {`
+	expected_type table.Type // for debugging only
+	is_sum_type   bool
 }
 
 pub struct MatchBranch {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 215ef45a0b..99576fd095 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -456,6 +456,7 @@ pub fn (c mut Checker) assign_stmt(assign_stmt mut ast.AssignStmt) {
 			})
 		}
 	}
+	c.expected_type = table.void_type
 }
 
 pub fn (c mut Checker) array_init(array_init mut ast.ArrayInit) table.Type {
@@ -839,7 +840,7 @@ pub fn (c mut Checker) ident(ident mut ast.Ident) table.Type {
 
 pub fn (c mut Checker) match_expr(node mut ast.MatchExpr) table.Type {
 	node.is_expr = c.expected_type != table.void_type
-	// node.expected_type = c.expected_type
+	node.expected_type = c.expected_type
 	cond_type := c.expr(node.cond)
 	if cond_type == 0 {
 		c.error('match 0 cond type', node.pos)
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index d7ec38f5a8..57898c3188 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -286,7 +286,7 @@ fn (g mut Gen) stmt(node ast.Stmt) {
 				g.stmts(it.stmts)
 				g.writeln('}')
 			}
-			//TODO:
+			// TODO:
 			else {}
 		}
 		ast.ForStmt {
@@ -1054,11 +1054,12 @@ fn (g mut Gen) match_expr(node ast.MatchExpr) {
 				g.writeln(') {')
 			}
 		}
-		if node.is_sum_type && branch.exprs.len > 0 {
+		// g.writeln('/* M sum_type=$node.is_sum_type is_expr=$node.is_expr exp_type=${g.typ(node.expected_type)}*/')
+		if node.is_sum_type && branch.exprs.len > 0 && !node.is_expr {
 			// The first node in expr is an ast.Type
 			// Use it to generate `it` variable.
-			fe := branch.exprs[0]
-			match fe {
+			first_expr := branch.exprs[0]
+			match first_expr {
 				ast.Type {
 					it_type := g.typ(it.typ)
 					// g.writeln('$it_type* it = ($it_type*)${tmp}.obj; // ST it')
@@ -1302,6 +1303,10 @@ fn (g mut Gen) return_statement(it ast.Return) {
 			}
 			// g.write('/*OPTIONAL*/')
 		}
+		if !table.type_is_ptr(g.fn_decl.return_type) && table.type_is_ptr(it.types[0]) {
+			// Automatic Dereference
+			g.write('*')
+		}
 		g.expr_with_cast(it.types[0], g.fn_decl.return_type, it.exprs[0])
 	}
 	g.writeln(';')