From 2fb7fba8562e1c41a377ffc455a622eac5c2aade Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Sat, 7 Dec 2019 16:58:43 +0300
Subject: [PATCH] require `else` in `match` statements

---
 vlib/builtin/utf8.v           | 10 +++---
 vlib/compiler/cgen.v          |  3 +-
 vlib/compiler/expression.v    |  4 +++
 vlib/compiler/gen_c.v         | 61 +++++++++++++++++++++++++----------
 vlib/compiler/if_match.v      |  8 ++---
 vlib/compiler/main.v          |  3 +-
 vlib/compiler/module_header.v |  1 +
 vlib/compiler/parser.v        |  1 +
 vlib/compiler/scanner.v       |  1 +
 vlib/compiler/table.v         | 10 +++---
 vlib/os/os.v                  |  1 +
 11 files changed, 69 insertions(+), 34 deletions(-)

diff --git a/vlib/builtin/utf8.v b/vlib/builtin/utf8.v
index e57e9f75e7..166ce91eb3 100644
--- a/vlib/builtin/utf8.v
+++ b/vlib/builtin/utf8.v
@@ -97,7 +97,7 @@ const (
 
 pub fn (_str string) to_wide() &u16 {
 	$if windows {
-		num_chars := int(C.MultiByteToWideChar(CP_UTF8, 0, _str.str, _str.len, 0, 0))
+		num_chars := (C.MultiByteToWideChar(CP_UTF8, 0, _str.str, _str.len, 0, 0))
 		mut wstr := &u16(malloc((num_chars + 1) * 2)) // sizeof(wchar_t)
 		if !isnil(wstr) {
 			C.MultiByteToWideChar(CP_UTF8, 0, _str.str, _str.len, wstr, num_chars)
@@ -111,7 +111,7 @@ pub fn (_str string) to_wide() &u16 {
 
 pub fn string_from_wide(_wstr &u16) string {
     $if windows {
-	    wstr_len := int(C.wcslen(_wstr))
+	    wstr_len := C.wcslen(_wstr)
 	    return string_from_wide2(_wstr, wstr_len)
     } $else {
         return ''
@@ -120,11 +120,11 @@ pub fn string_from_wide(_wstr &u16) string {
 
 pub fn string_from_wide2(_wstr &u16, len int) string {
     $if windows {
-    	num_chars := int(C.WideCharToMultiByte(CP_UTF8, 0, _wstr, len, 0, 0, 0, 0))
-    	mut str_to := &byte(malloc(num_chars + 1))
+    	num_chars := C.WideCharToMultiByte(CP_UTF8, 0, _wstr, len, 0, 0, 0, 0))
+    	mut str_to := malloc(num_chars + 1)
     	if !isnil(str_to) {
     		C.WideCharToMultiByte(CP_UTF8, 0, _wstr, len, str_to, num_chars, 0, 0)
-		    C.memset(&byte(str_to) + num_chars, 0, 1)
+		    C.memset(str_to + num_chars, 0, 1)
 	    }
 	    return tos2(str_to)
     } $else {
diff --git a/vlib/compiler/cgen.v b/vlib/compiler/cgen.v
index 34d98ec876..793f6f27b9 100644
--- a/vlib/compiler/cgen.v
+++ b/vlib/compiler/cgen.v
@@ -301,8 +301,9 @@ fn os_name_to_ifdef(name string) string {
 		'js' {return '_VJS' }
 		'solaris'{ return '__sun' }
 		'haiku' { return '__haiku__' }
+		else { verror('bad os ifdef name "$name"') }
 	}
-	verror('bad os ifdef name "$name"')
+	//verror('bad os ifdef name "$name"')
 	return ''
 }
 
diff --git a/vlib/compiler/expression.v b/vlib/compiler/expression.v
index 1d30a30caa..6de9755ded 100644
--- a/vlib/compiler/expression.v
+++ b/vlib/compiler/expression.v
@@ -97,6 +97,7 @@ fn (p mut Parser) bterm() string {
 				.ge { p.cgen.set_placeholder(ph, 'string_ge(') }
 				.gt { p.cgen.set_placeholder(ph, 'string_gt(') }
 				.lt { p.cgen.set_placeholder(ph, 'string_lt(') }
+				else { }
 			}
 		}
 		if is_ustr {
@@ -108,6 +109,7 @@ fn (p mut Parser) bterm() string {
 				.ge { p.cgen.set_placeholder(ph, 'ustring_ge(') }
 				.gt { p.cgen.set_placeholder(ph, 'ustring_gt(') }
 				.lt { p.cgen.set_placeholder(ph, 'ustring_lt(') }
+				else { }
 			}
 		}
 		if is_float && p.cur_fn.name != 'f32_abs' && p.cur_fn.name != 'f64_abs' {
@@ -119,6 +121,7 @@ fn (p mut Parser) bterm() string {
 				.ge { p.cgen.set_placeholder(ph, '${expr_type}_ge(') }
 				.gt { p.cgen.set_placeholder(ph, '${expr_type}_gt(') }
 				.lt { p.cgen.set_placeholder(ph, '${expr_type}_lt(') }
+				else { }
 			}
 		}
 	}
@@ -573,6 +576,7 @@ fn (p mut Parser) term() string {
 				.mul {   p.handle_operator('*', typ, 'op_mul', ph, T) }
 				.div {   p.handle_operator('/', typ, 'op_div', ph, T) }
 				.mod {   p.handle_operator('%', typ, 'op_mod', ph, T) }
+				else {}
 			}
 			continue
 		}
diff --git a/vlib/compiler/gen_c.v b/vlib/compiler/gen_c.v
index 5baaf52489..5e8e2e92fd 100644
--- a/vlib/compiler/gen_c.v
+++ b/vlib/compiler/gen_c.v
@@ -260,6 +260,7 @@ fn (table mut Table) fn_gen_name(f &Fn) string {
 				`*` { name = name.replace('*', 'op_mul') }
 				`/` { name = name.replace('/', 'op_div') }
 				`%` { name = name.replace('%', 'op_mod') }
+				else {}
 			}
 		}
 	}
@@ -606,24 +607,50 @@ fn type_default(typ string) string {
 		return '{0}'
 	}
 	// Default values for other types are not needed because of mandatory initialization
-	match typ {
-	'bool'{ return '0'}
-	'string'{ return 'tos3("")'}
-	'i8'{ return '0'}
-	'i16'{ return '0'}
-	'i64'{ return '0'}
-	'u16'{ return '0'}
-	'u32'{ return '0'}
-	'u64'{ return '0'}
-	'byte'{ return '0'}
-	'int'{ return '0'}
-	'rune'{ return '0'}
-	'f32'{ return '0.0'}
-	'f64'{ return '0.0'}
-	'byteptr'{ return '0'}
-	'voidptr'{ return '0'}
+	 match typ {
+ 'bool'{ return '0'}
+ 'string'{ return 'tos3("")'}
+ 'i8'{ return '0'}
+ 'i16'{ return '0'}
+ 'i64'{ return '0'}
+ 'u16'{ return '0'}
+ 'u32'{ return '0'}
+ 'u64'{ return '0'}
+ 'byte'{ return '0'}
+ 'int'{ return '0'}
+ 'rune'{ return '0'}
+ 'f32'{ return '0.0'}
+ 'f64'{ return '0.0'}
+ 'byteptr'{ return '0'}
+ 'voidptr'{ return '0'}
+else {}
+ }
+ return '{0}'
+
+
+	// TODO this results in
+	// error: expected a field designator, such as '.field = 4'
+	//- Empty ee= (Empty) { . =  {0}  } ;
+	/*
+	return match typ {
+		'bool'{ '0'}
+		'string'{ 'tos3("")'}
+		'i8'{ '0'}
+		'i16'{ '0'}
+		'i64'{ '0'}
+		'u16'{ '0'}
+		'u32'{ '0'}
+		'u64'{ '0'}
+		'byte'{ '0'}
+		'int'{ '0'}
+		'rune'{ '0'}
+		'f32'{ '0.0'}
+		'f64'{ '0.0'}
+		'byteptr'{ '0'}
+		'voidptr'{ '0'}
+		else { '{0} '}
 	}
-	return '{0}'
+	*/
 }
 
 fn (p mut Parser) gen_array_push(ph int, typ, expr_type, tmp, elm_type string) {
diff --git a/vlib/compiler/if_match.v b/vlib/compiler/if_match.v
index 7a7e069359..284e7fbbfa 100644
--- a/vlib/compiler/if_match.v
+++ b/vlib/compiler/if_match.v
@@ -27,11 +27,9 @@ fn (p mut Parser) match_statement(is_expr bool) string {
 
 	// stores typ of resulting variable
 	mut res_typ := ''
-
 	defer {
 		p.check(.rcbr)
 	}
-
 	for p.tok != .rcbr {
 		if p.tok == .key_else {
 			p.check(.key_else)
@@ -206,10 +204,10 @@ fn (p mut Parser) match_statement(is_expr bool) string {
 		p.fgen_nl()
 	}
 
-	if is_expr {
+	//if is_expr {
 		// we get here if no else found, ternary requires "else" branch
-		p.error('Match expression requires "else"')
-	}
+		p.warn('match expression requires `else`')
+	//}
 
 	p.returns = false // only get here when no default, so return is not guaranteed
 
diff --git a/vlib/compiler/main.v b/vlib/compiler/main.v
index d851202fd5..1a928c40c0 100644
--- a/vlib/compiler/main.v
+++ b/vlib/compiler/main.v
@@ -1173,8 +1173,9 @@ pub fn os_from_string(os string) OS {
 			verror('use the flag `-cc msvc` to build using msvc')
 		}
 		'haiku' { return .haiku }
+		else { panic('bad os $os') }
 	}
-	println('bad os $os') // todo panic?
+	//println('bad os $os') // todo panic?
 	return .linux
 }
 
diff --git a/vlib/compiler/module_header.v b/vlib/compiler/module_header.v
index f4a65e39b9..8a0af95e64 100644
--- a/vlib/compiler/module_header.v
+++ b/vlib/compiler/module_header.v
@@ -80,6 +80,7 @@ fn generate_vh(mod string) {
 				.key_const  {	g.generate_const() }
 				.key_struct {	g.generate_type()  }
 				.key_type   {	g.generate_alias() }
+				else {}
 			}
 		}
 	}
diff --git a/vlib/compiler/parser.v b/vlib/compiler/parser.v
index 681fb8d31a..2e4c068d96 100644
--- a/vlib/compiler/parser.v
+++ b/vlib/compiler/parser.v
@@ -788,6 +788,7 @@ fn key_to_type_cat(tok TokenKind) TypeCategory {
 		.key_interface { return .interface_ }
 		.key_struct    { return .struct_    }
 		.key_union     { return .union_     }
+		else {}
 	}
 	verror('Unknown token: $tok')
 	return .builtin
diff --git a/vlib/compiler/scanner.v b/vlib/compiler/scanner.v
index 67b42f87e5..052a46ad48 100644
--- a/vlib/compiler/scanner.v
+++ b/vlib/compiler/scanner.v
@@ -637,6 +637,7 @@ fn (s mut Scanner) scan() ScanRes {
 		}
 		return scan_res(.div, '')
 	 }
+	else { }
 	}
 	$if windows {
 		if c == `\0` {
diff --git a/vlib/compiler/table.v b/vlib/compiler/table.v
index 7ec10b122e..5d5ceadd0a 100644
--- a/vlib/compiler/table.v
+++ b/vlib/compiler/table.v
@@ -819,13 +819,13 @@ fn (table &Table) cgen_name_type_pair(name, typ string) string {
 
 fn is_valid_int_const(val, typ string) bool {
 	x := val.int()
-	match typ {
-	 'byte' { return 0 <= x && x <= 255 }
-	 'u16' { return 0 <= x && x <= 65535 }
+	return match typ {
+	 'byte' { 0 <= x && x <= 255 }
+	 'u16' { 0 <= x && x <= 65535 }
 	//case 'u32': return 0 <= x && x <= math.MaxU32
 	//case 'u64': return 0 <= x && x <= math.MaxU64
 	//////////////
-	 'i8' { return -128 <= x && x <= 127 }
+	 'i8' { -128 <= x && x <= 127 }
 	/*
 	case 'i16': return math.min_i16 <= x && x <= math.max_i16
 	case 'int': return math.min_i32 <= x && x <= math.max_i32
@@ -833,8 +833,8 @@ fn is_valid_int_const(val, typ string) bool {
 	//case 'i64':
 		//x64 := val.i64()
 		//return i64(-(1<<63)) <= x64 && x64 <= i64((1<<63)-1)
+		else { true }
 	}
-	return true
 }
 
 fn (p mut Parser) typ_to_fmt(typ string, level int) string {
diff --git a/vlib/os/os.v b/vlib/os/os.v
index 5831fe300d..31644f9cb4 100644
--- a/vlib/os/os.v
+++ b/vlib/os/os.v
@@ -464,6 +464,7 @@ pub fn sigint_to_signal_name(si int) string {
 		13 {return 'SIGPIPE'}
 		14 {return 'SIGALRM'}
 		15 {return 'SIGTERM'}
+		else { }
 	}
 	$if linux {
 		// From `man 7 signal` on linux: