cgen: allow unwrapping of x as string expr

vlib/v/gen/c/cgen.v

@@ -4996,26 +4996,7 @@ fn (mut g Gen) ident(node ast.Ident) {
 					g.write(name)
 				}
 			} else {
-				g.write('/*opt*/')
-				styp := g.base_type(node.info.typ)
-				if is_auto_heap {
-					g.write('(*(${styp}*)${name}->data)')
-				} else {
-					type_sym := g.table.sym(node.info.typ)
-					if type_sym.kind == .alias {
-						// Alias to Option type
-						parent_typ := (type_sym.info as ast.Alias).parent_type
-						if parent_typ.has_flag(.option) {
-							g.write('*((${g.base_type(parent_typ)}*)')
-						}
-						g.write('(*(${styp}*)${name}.data)')
-						if parent_typ.has_flag(.option) {
-							g.write('.data)')
-						}
-					} else {
-						g.write('(*(${styp}*)${name}.data)')
-					}
-				}
+				g.unwrap_option_type(node.info.typ, name, is_auto_heap)
 			}
 			if node.or_expr.kind != .absent && !(g.inside_opt_or_res && g.inside_assign
 				&& !g.is_assign_lhs) {
@@ -7801,7 +7782,17 @@ fn (mut g Gen) as_cast(node ast.AsCast) {
 			g.as_cast_type_names[idx] = variant_sym.name
 		}
 	} else {
-		g.expr(node.expr)
+		if node.expr is ast.Ident {
+			if node.expr.info is ast.IdentVar {
+				if node.expr.info.is_option {
+					g.unwrap_option_type(unwrapped_node_typ, node.expr.name, node.expr.is_auto_heap())
+				} else {
+					g.expr(node.expr)
+				}
+			}
+		} else {
+			g.expr(node.expr)
+		}
 	}
 }
 

vlib/v/gen/c/utils.v

@@ -32,7 +32,7 @@ fn (mut g Gen) unwrap_generic(typ ast.Type) ast.Type {
 				}
 			}
 		} else if g.table.sym(typ).kind == .struct {
-			// resolve selector `a.foo` where `a` is struct[T] on non generic function	
+			// resolve selector `a.foo` where `a` is struct[T] on non generic function
 			sym := g.table.sym(typ)
 			if sym.info is ast.Struct {
 				if sym.info.generic_types.len > 0 {
@@ -145,3 +145,27 @@ fn (mut g Gen) dot_or_ptr(val_type ast.Type) string {
 		'.'
 	}
 }
+
+@[inline]
+fn (mut g Gen) unwrap_option_type(typ ast.Type, name string, is_auto_heap bool) {
+	g.write('/*opt*/')
+	styp := g.base_type(typ)
+	if is_auto_heap {
+		g.write('(*(${styp}*)${name}->data)')
+	} else {
+		type_sym := g.table.sym(typ)
+		if type_sym.kind == .alias {
+			// Alias to Option type
+			parent_typ := (type_sym.info as ast.Alias).parent_type
+			if parent_typ.has_flag(.option) {
+				g.write('*((${g.base_type(parent_typ)}*)')
+			}
+			g.write('(*(${styp}*)${name}.data)')
+			if parent_typ.has_flag(.option) {
+				g.write('.data)')
+			}
+		} else {
+			g.write('(*(${styp}*)${name}.data)')
+		}
+	}
+}

vlib/v/tests/option_unwrap_as_cast_test.v

@@ -0,0 +1,23 @@
+fn get_opt(a int) ?string {
+	if a < 0 {
+		return none
+	}
+	return 'success'
+}
+
+fn get_opt_int(a int) ?int {
+	if a < 0 {
+		return none
+	}
+	return 12
+}
+
+fn test_option_unwrap_as_cast() {
+	x := get_opt(1)
+	d := get_opt_int(12)
+	dump(d as int == 12)
+	dump('${x as string}' == 'success')
+
+	assert d as int == 12
+	assert x as string == 'success'
+}