From 34e0b164ebb62e7f5ca5c809e9f384636d69a8cd Mon Sep 17 00:00:00 2001
From: Alexander Medvednikov <alexander@medvednikov.com>
Date: Wed, 7 Aug 2019 08:19:27 +0200
Subject: [PATCH] make function arguments immutable by default

---
 CHANGELOG.md                             |  4 +++
 compiler/fn.v                            |  4 +--
 compiler/jsgen.v                         |  8 +++---
 compiler/main.v                          |  2 +-
 compiler/parser.v                        | 18 ++++++++------
 compiler/scanner.v                       |  2 +-
 compiler/table.v                         | 17 +++++++------
 compiler/vfmt.v                          |  6 +++--
 vlib/crypto/cipher/xor_generic.v         |  8 +++---
 vlib/crypto/md5/md5.v                    | 14 +++++------
 vlib/crypto/md5/md5block_generic.v       |  2 +-
 vlib/crypto/sha1/sha1.v                  |  6 ++---
 vlib/crypto/sha1/sha1block_generic.v     |  2 +-
 vlib/crypto/sha256/sha256.v              | 24 +++++++++---------
 vlib/crypto/sha256/sha256block_generic.v |  2 +-
 vlib/crypto/sha512/sha512.v              | 31 ++++++++++++------------
 vlib/crypto/sha512/sha512block_generic.v |  2 +-
 vlib/encoding/binary/binary.v            | 16 ++++++------
 vlib/gl/gl.v                             |  4 ++-
 vlib/math/math.v                         |  6 ++++-
 vlib/math/math_test.v                    |  2 ++
 vlib/net/urllib/urllib.v                 | 10 +++++---
 22 files changed, 107 insertions(+), 83 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 23b2bef77c..196e65b0b1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,10 @@
 ## V 0.1.18
 
 - Map initialization syntax: `m := { ‘foo’: ‘bar’, ‘baz’: ‘kek’ }`  
+- `libcurl` dependency was removed from `http` module. 
+- All function arguments are now immutable by default (previously they could be 
+  modifed inside the function). 
+
 
 
 ## V 0.1.17 
diff --git a/compiler/fn.v b/compiler/fn.v
index 666416be9f..e5a934b229 100644
--- a/compiler/fn.v
+++ b/compiler/fn.v
@@ -512,8 +512,8 @@ fn (p mut Parser) async_fn_call(f Fn, method_ph int, receiver_var, receiver_type
 	// Normal function => just its name, method => TYPE_FN.name
 	mut fn_name := f.name
 	if f.is_method {
-		receiver_type = receiver_type.replace('*', '')
-		fn_name = '${receiver_type}_${f.name}'
+		fn_name = receiver_type.replace('*', '') + '_' + f.name 
+		//fn_name = '${receiver_type}_${f.name}'
 	}
 	// Generate tmp struct with args
 	arg_struct_name := 'thread_arg_$fn_name'
diff --git a/compiler/jsgen.v b/compiler/jsgen.v
index 9fc9a7b246..5923407a44 100644
--- a/compiler/jsgen.v
+++ b/compiler/jsgen.v
@@ -115,8 +115,8 @@ fn is_js_prim(typ string) bool {
 	typ == 'i8' || typ == 'i16' || typ == 'i32' || typ == 'i64'
 }
 
-fn (p mut Parser) decode_array(typ string) string {
-	typ = typ.replace('array_', '')
+fn (p mut Parser) decode_array(array_type string) string {
+	typ := array_type.replace('array_', '')
 	t := p.table.find_type(typ)
 	fn_name := js_dec_name(typ)
 	// If we have `[]Profile`, have to register a Profile en(de)coder first
@@ -149,8 +149,8 @@ fn js_dec_name(typ string) string {
 	return name
 }
 
-fn (p &Parser) encode_array(typ string) string {
-	typ = typ.replace('array_', '')
+fn (p &Parser) encode_array(array_type string) string {
+	typ := array_type.replace('array_', '')
 	fn_name := js_enc_name(typ)
 	return '
 o = cJSON_CreateArray();
diff --git a/compiler/main.v b/compiler/main.v
index 81891f7eac..4b2851e07e 100644
--- a/compiler/main.v
+++ b/compiler/main.v
@@ -669,7 +669,7 @@ fn (v V) run_compiled_executable_and_exit() {
 	exit(0)
 }
 
-fn (c &V) cc_windows_cross() {
+fn (c mut V) cc_windows_cross() {
        if !c.out_name.ends_with('.exe') {
                c.out_name = c.out_name + '.exe'
        }
diff --git a/compiler/parser.v b/compiler/parser.v
index 08c2adb6b0..f267d50e9c 100644
--- a/compiler/parser.v
+++ b/compiler/parser.v
@@ -1192,7 +1192,8 @@ fn (p mut Parser) statement(add_semi bool) string {
 fn (p mut Parser) assign_statement(v Var, ph int, is_map bool) {
 	p.log('assign_statement() name=$v.name tok=')
 	tok := p.tok
-	if !v.is_mut && !v.is_arg && !p.pref.translated && !v.is_global{
+	//if !v.is_mut && !v.is_arg && !p.pref.translated && !v.is_global{
+	if !v.is_mut && !p.pref.translated && !v.is_global{
 		p.error('`$v.name` is immutable')
 	}
 	if !v.is_changed {
@@ -1799,7 +1800,8 @@ fn (p mut Parser) dot(str_typ string, method_ph int) string {
 	return method.typ
 }
 
-fn (p mut Parser) index_expr(typ string, fn_ph int) string {
+fn (p mut Parser) index_expr(typ_ string, fn_ph int) string {
+	mut typ := typ_ 
 	// a[0]
 	v := p.expr_var
 	//if p.fileis('fn_test.v') {
@@ -2361,8 +2363,8 @@ fn (p mut Parser) char_expr() {
 }
 
 
-fn format_str(str string) string {
-	str = str.replace('"', '\\"')
+fn format_str(_str string) string {
+	mut str := _str.replace('"', '\\"')
 	$if windows {
 		str = str.replace('\r\n', '\\n')
 	} 
@@ -3298,9 +3300,11 @@ fn (p mut Parser) go_statement() {
 
 fn (p mut Parser) register_var(v Var) {
 	if v.line_nr == 0 {
-		v.line_nr = p.scanner.line_nr
-	}
-	p.cur_fn.register_var(v)
+		//v.line_nr = p.scanner.line_nr
+		p.cur_fn.register_var({ v | line_nr: p.scanner.line_nr }) 
+	} else { 
+		p.cur_fn.register_var(v)
+	} 
 }
 
 // user:=jsdecode(User, user_json_string)
diff --git a/compiler/scanner.v b/compiler/scanner.v
index c1c15ce6ec..24d423cf0a 100644
--- a/compiler/scanner.v
+++ b/compiler/scanner.v
@@ -550,7 +550,7 @@ fn (s mut Scanner) scan() ScanRes {
 
 fn (s &Scanner) error(msg string) {
 	file := s.file_path.all_after('/')
-	println('$file:${s.line_nr + 1} panic: $msg')
+	println('$file:${s.line_nr + 1} $msg')
 	exit(1)
 }
 
diff --git a/compiler/table.v b/compiler/table.v
index ea9a53d9d1..118a8bcaaf 100644
--- a/compiler/table.v
+++ b/compiler/table.v
@@ -242,7 +242,8 @@ fn (t mut Table) register_fn(new_fn Fn) {
 	t.fns[new_fn.name] = new_fn 
 }
 
-fn (table &Table) known_type(typ string) bool {
+fn (table &Table) known_type(typ_ string) bool {
+	mut typ := typ_ 
 	// 'byte*' => look up 'byte', but don't mess up fns
 	if typ.ends_with('*') && !typ.contains(' ') {
 		typ = typ.left(typ.len - 1)
@@ -441,7 +442,8 @@ fn (p &Parser) find_type(name string) *Type {
 	return typ
 }
 
-fn (t &Table) find_type(name string) *Type {
+fn (t &Table) find_type(name_ string) *Type {
+	mut name := name_ 
 	if name.ends_with('*') && !name.contains(' ') {
 		name = name.left(name.len - 1)
 	}
@@ -454,7 +456,9 @@ fn (t &Table) find_type(name string) *Type {
 	return &Type{}
 }
 
-fn (p mut Parser) _check_types(got, expected string, throw bool) bool {
+fn (p mut Parser) _check_types(got_, expected_ string, throw bool) bool {
+	mut got := got_ 
+	mut expected := expected_ 
 	p.log('check types got="$got" exp="$expected"  ')
 	if p.pref.translated {
 		return true
@@ -582,8 +586,7 @@ fn (p mut Parser) satisfies_interface(interface_name, _typ string, throw bool) b
 
 fn type_default(typ string) string {
 	if typ.starts_with('array_') {
-		typ = typ.right(6)
-		return 'new_array(0, 1, sizeof($typ))'
+		return 'new_array(0, 1, sizeof( ${typ.right(6)} ))'
 	}
 	// Always set pointers to 0
 	if typ.ends_with('*') {
@@ -776,8 +779,8 @@ fn (p mut Parser) typ_to_fmt(typ string, level int) string {
 	return ''
 }
 
-fn is_compile_time_const(s string) bool {
-	s = s.trim_space()
+fn is_compile_time_const(s_ string) bool {
+	s := s_.trim_space()
 	if s == '' {
 		return false
 	}
diff --git a/compiler/vfmt.v b/compiler/vfmt.v
index 7f2129607b..a1c7a79e53 100644
--- a/compiler/vfmt.v
+++ b/compiler/vfmt.v
@@ -7,7 +7,8 @@ module main
 import strings 
 
 // fmt helpers
-fn (scanner mut Scanner) fgen(s string) {
+fn (scanner mut Scanner) fgen(s_ string) {
+	mut s := s_ 
 	if scanner.fmt_line_empty {
 		s = strings.repeat(`\t`, scanner.fmt_indent) + s
 	}
@@ -15,7 +16,8 @@ fn (scanner mut Scanner) fgen(s string) {
 	scanner.fmt_line_empty = false
 }
 
-fn (scanner mut Scanner) fgenln(s string) {
+fn (scanner mut Scanner) fgenln(s_ string) {
+	mut s := s_ 
 	if scanner.fmt_line_empty {
 		s = strings.repeat(`\t`, scanner.fmt_indent) + s
 	}
diff --git a/vlib/crypto/cipher/xor_generic.v b/vlib/crypto/cipher/xor_generic.v
index bdd976f6ff..12d6a497c9 100644
--- a/vlib/crypto/cipher/xor_generic.v
+++ b/vlib/crypto/cipher/xor_generic.v
@@ -8,7 +8,7 @@ module cipher
 
 // xor_bytes xors the bytes in a and b. The destination should have enough
 // space, otherwise xor_bytes will panic. Returns the number of bytes xor'd.
-pub fn xor_bytes(dst, a, b []byte) int {
+pub fn xor_bytes(dst mut []byte, a, b []byte) int {
 	mut n := a.len
 	if b.len < n {
 		n = b.len
@@ -17,13 +17,13 @@ pub fn xor_bytes(dst, a, b []byte) int {
 		return 0
 	}
 
-	safe_xor_bytes(dst, a, b, n)
+	safe_xor_bytes(mut dst, a, b, n)
 
 	return n
 }
 
 // n needs to be smaller or equal than the length of a and b.
-pub fn safe_xor_bytes(dst, a, b []byte, n int) {
+pub fn safe_xor_bytes(dst mut []byte, a, b []byte, n int) {
 	for i := 0; i < n; i++ {
 		dst[i] = a[i] ^ b[i]
 	}
@@ -32,5 +32,5 @@ pub fn safe_xor_bytes(dst, a, b []byte, n int) {
 // fast_xor_words XORs multiples of 4 or 8 bytes (depending on architecture.)
 // The slice arguments a and b are assumed to be of equal length.
 pub fn xor_words(dst, a, b []byte) {
-	safe_xor_bytes(dst, a, b, b.len)
+	safe_xor_bytes(mut dst, a, b, b.len)
 }
diff --git a/vlib/crypto/md5/md5.v b/vlib/crypto/md5/md5.v
index d263fa3c2b..62c541924e 100644
--- a/vlib/crypto/md5/md5.v
+++ b/vlib/crypto/md5/md5.v
@@ -55,7 +55,7 @@ pub fn new() *Digest {
 	return d
 }
 
-pub fn (d mut Digest) write(p []byte) ?int {
+pub fn (d mut Digest) write(p mut []byte) ?int {
 	nn := p.len
 	d.len += u64(nn)
 	if d.nx > 0 {
@@ -106,8 +106,8 @@ pub fn (d mut Digest) checksum() []byte {
     mut tmp := [byte(0); 1 + 63 + 8]
 	tmp[0] = 0x80
 	pad := (55 - int(d.len)) % 64 // calculate number of padding bytes
-	binary.little_endian_put_u64(tmp.right(1+pad), u64(d.len<<u64(3))) // append length in bits
-    d.write(tmp.left(1+pad+8))
+	binary.little_endian_put_u64(mut tmp.right(1+pad), u64(d.len<<u64(3))) // append length in bits
+    d.write(mut tmp.left(1+pad+8))
 
 	// The previous write ensures that a whole number of
 	// blocks (i.e. a multiple of 64 bytes) have been hashed.
@@ -117,10 +117,10 @@ pub fn (d mut Digest) checksum() []byte {
 
     digest := [byte(0); Size]
 
-	binary.little_endian_put_u32(digest, d.s[0])
-	binary.little_endian_put_u32(digest.right(4), d.s[1])
-	binary.little_endian_put_u32(digest.right(8), d.s[2])
-	binary.little_endian_put_u32(digest.right(12), d.s[3])
+	binary.little_endian_put_u32(mut digest, d.s[0])
+	binary.little_endian_put_u32(mut digest.right(4), d.s[1])
+	binary.little_endian_put_u32(mut digest.right(8), d.s[2])
+	binary.little_endian_put_u32(mut digest.right(12), d.s[3])
 	return digest
 }
 
diff --git a/vlib/crypto/md5/md5block_generic.v b/vlib/crypto/md5/md5block_generic.v
index 48d7a1ad66..65f88ba858 100644
--- a/vlib/crypto/md5/md5block_generic.v
+++ b/vlib/crypto/md5/md5block_generic.v
@@ -13,7 +13,7 @@ import (
 	encoding.binary
 )
 
-fn block_generic(dig &Digest, p []byte) {
+fn block_generic(dig mut Digest, p []byte) {
 	// load state
 	mut a := dig.s[0]
 	mut b := dig.s[1]
diff --git a/vlib/crypto/sha1/sha1.v b/vlib/crypto/sha1/sha1.v
index d9e672e06e..131224f34a 100644
--- a/vlib/crypto/sha1/sha1.v
+++ b/vlib/crypto/sha1/sha1.v
@@ -58,7 +58,7 @@ pub fn new() &Digest {
 	return d
 }
 
-pub fn (d mut Digest) write(p []byte) ?int {
+pub fn (d mut Digest) write(p mut []byte) ?int {
 	nn := p.len
 	d.len += u64(nn)
 
@@ -108,9 +108,9 @@ fn (d mut Digest) checksum() []byte {
 	tmp[0] = 0x80
 
 	if int(len)%64 < 56 {
-		d.write(tmp.left(56-int(len)%64))
+		d.write(mut tmp.left(56-int(len)%64))
 	} else {
-		d.write(tmp.left(64+56-int(len)%64))
+		d.write(mut tmp.left(64+56-int(len)%64))
 	}
 
 	// Length in bits.
diff --git a/vlib/crypto/sha1/sha1block_generic.v b/vlib/crypto/sha1/sha1block_generic.v
index 48cee2cd77..ae88423b86 100644
--- a/vlib/crypto/sha1/sha1block_generic.v
+++ b/vlib/crypto/sha1/sha1block_generic.v
@@ -17,7 +17,7 @@ const (
 	_K3 = 0xCA62C1D6
 )
 
-fn block_generic(dig &Digest, p []byte) {
+fn block_generic(dig mut Digest, p []byte) {
 	mut w := [u32(0); 16]
 	mut h0 := dig.h[0]
 	mut h1 := dig.h[1]
diff --git a/vlib/crypto/sha256/sha256.v b/vlib/crypto/sha256/sha256.v
index cc65096af8..083796b5aa 100644
--- a/vlib/crypto/sha256/sha256.v
+++ b/vlib/crypto/sha256/sha256.v
@@ -51,7 +51,7 @@ mut:
 	is224 bool // mark if this digest is SHA-224
 }
 
-fn (d &Digest) reset() {
+fn (d mut Digest) reset() {
 	d.h = [u32(0); 8]
 	d.x = [byte(0); Chunk]
 	if !d.is224 {
@@ -92,7 +92,7 @@ pub fn new224() *Digest {
 	return d
 }
 
-fn (d mut Digest) write(p []byte) ?int {
+fn (d mut Digest) write(p mut []byte) ?int {
 	nn := p.len
 	d.len += u64(nn)
 	if d.nx > 0 {
@@ -145,14 +145,14 @@ fn (d mut Digest) checksum() []byte {
 	mut tmp := [byte(0); 64]
 	tmp[0] = 0x80
 	if int(len)%64 < 56 {
-		d.write(tmp.left(56-int(len)%64))
+		d.write(mut tmp.left(56-int(len)%64))
 	} else {
-		d.write(tmp.left(64+56-int(len)%64))
+		d.write(mut tmp.left(64+56-int(len)%64))
 	}
 
 	// Length in bits.
 	len <<= u64(3)
-	binary.big_endian_put_u64(tmp, len)
+	binary.big_endian_put_u64(mut tmp, len)
 	d.write(tmp.left(8))
 
 	if d.nx != 0 {
@@ -161,13 +161,13 @@ fn (d mut Digest) checksum() []byte {
 
 	digest := [byte(0); Size]
 
-	binary.big_endian_put_u32(digest, d.h[0])
-	binary.big_endian_put_u32(digest.right(4), d.h[1])
-	binary.big_endian_put_u32(digest.right(8), d.h[2])
-	binary.big_endian_put_u32(digest.right(12), d.h[3])
-	binary.big_endian_put_u32(digest.right(16), d.h[4])
-	binary.big_endian_put_u32(digest.right(20), d.h[5])
-	binary.big_endian_put_u32(digest.right(24), d.h[6])
+	binary.big_endian_put_u32(mut digest, d.h[0])
+	binary.big_endian_put_u32(mut digest.right(4), d.h[1])
+	binary.big_endian_put_u32(mut digest.right(8), d.h[2])
+	binary.big_endian_put_u32(mut digest.right(12), d.h[3])
+	binary.big_endian_put_u32(mut digest.right(16), d.h[4])
+	binary.big_endian_put_u32(mut digest.right(20), d.h[5])
+	binary.big_endian_put_u32(mut digest.right(24), d.h[6])
 	if !d.is224 {
 		binary.big_endian_put_u32(digest.right(28), d.h[7])
 	}
diff --git a/vlib/crypto/sha256/sha256block_generic.v b/vlib/crypto/sha256/sha256block_generic.v
index c31923f5cb..c5bebef24e 100644
--- a/vlib/crypto/sha256/sha256block_generic.v
+++ b/vlib/crypto/sha256/sha256block_generic.v
@@ -80,7 +80,7 @@ const (
 	]
 )
 
-fn block_generic(dig &Digest, p []byte) {
+fn block_generic(dig mut Digest, p []byte) {
 	mut w := [u32(0); 64]
 	
 	mut h0 := dig.h[0]
diff --git a/vlib/crypto/sha512/sha512.v b/vlib/crypto/sha512/sha512.v
index 5b92600e01..7dd80b473a 100644
--- a/vlib/crypto/sha512/sha512.v
+++ b/vlib/crypto/sha512/sha512.v
@@ -146,14 +146,15 @@ fn new384() *Digest {
 	return _new(crypto.Hash.SHA384)
 }
 
-fn (d mut Digest) write(p []byte) ?int {
+fn (d mut Digest) write(p_ []byte) ?int {
+	mut p := p_ 
 	nn := p.len
 	d.len += u64(nn)
 	if d.nx > 0 {
 		n := copy(d.x.right(d.nx), p)
 		d.nx += n
 		if d.nx == Chunk {
-			block(d, d.x)
+			block(mut d, d.x)
 			d.nx = 0
 		}
 		if n >= p.len {
@@ -164,7 +165,7 @@ fn (d mut Digest) write(p []byte) ?int {
 	}
 	if p.len >= Chunk {
 		n := p.len &~ (Chunk - 1)
-		block(d, p.left(n))
+		block(mut d, p.left(n))
 		if n >= p.len {
 			p = []byte
 		} else {
@@ -217,8 +218,8 @@ fn (d mut Digest) checksum() []byte {
 	// Length in bits.
 	len <<= u64(3)
 
-	binary.big_endian_put_u64(tmp, u64(0)) // upper 64 bits are always zero, because len variable has type u64
-	binary.big_endian_put_u64(tmp.right(8), len)
+	binary.big_endian_put_u64(mut tmp, u64(0)) // upper 64 bits are always zero, because len variable has type u64
+	binary.big_endian_put_u64(mut tmp.right(8), len)
 	d.write(tmp.left(16))
 
 	if d.nx != 0 {
@@ -227,15 +228,15 @@ fn (d mut Digest) checksum() []byte {
 
 	mut digest := [byte(0); Size]
 	
-	binary.big_endian_put_u64(digest, d.h[0])
-	binary.big_endian_put_u64(digest.right(8), d.h[1])
-	binary.big_endian_put_u64(digest.right(16), d.h[2])
-	binary.big_endian_put_u64(digest.right(24), d.h[3])
-	binary.big_endian_put_u64(digest.right(32), d.h[4])
-	binary.big_endian_put_u64(digest.right(40), d.h[5])
+	binary.big_endian_put_u64(mut digest, d.h[0])
+	binary.big_endian_put_u64(mut digest.right(8), d.h[1])
+	binary.big_endian_put_u64(mut digest.right(16), d.h[2])
+	binary.big_endian_put_u64(mut digest.right(24), d.h[3])
+	binary.big_endian_put_u64(mut digest.right(32), d.h[4])
+	binary.big_endian_put_u64(mut digest.right(40), d.h[5])
 	if d.function != crypto.Hash.SHA384 {
-		binary.big_endian_put_u64(digest.right(48), d.h[6])
-		binary.big_endian_put_u64(digest.right(56), d.h[7])
+		binary.big_endian_put_u64(mut digest.right(48), d.h[6])
+		binary.big_endian_put_u64(mut digest.right(56), d.h[7])
 	}
 
 	return digest
@@ -278,10 +279,10 @@ pub fn sum512_256(data []byte) []byte {
 	return sum256
 }
 
-fn block(dig &Digest, p []byte) {
+fn block(dig mut Digest, p []byte) {
 	// For now just use block_generic until we have specific
 	// architecture optimized versions
-	block_generic(dig, p)
+	block_generic(mut dig, p)
 }
 
 pub fn (d &Digest) size() int {
diff --git a/vlib/crypto/sha512/sha512block_generic.v b/vlib/crypto/sha512/sha512block_generic.v
index e1d692342d..dd9ede3e0c 100644
--- a/vlib/crypto/sha512/sha512block_generic.v
+++ b/vlib/crypto/sha512/sha512block_generic.v
@@ -94,7 +94,7 @@ const(
 	]
 )
 
-fn block_generic(dig &Digest, p []byte) {
+fn block_generic(dig mut Digest, p []byte) {
 	mut w := [u64(0); 80]
 	
 	mut h0 := dig.h[0]
diff --git a/vlib/encoding/binary/binary.v b/vlib/encoding/binary/binary.v
index 69790d514f..440ce2e7c3 100644
--- a/vlib/encoding/binary/binary.v
+++ b/vlib/encoding/binary/binary.v
@@ -12,7 +12,7 @@ pub fn little_endian_endian_u16(b []byte) u16 {
 }
 
 
-pub fn little_endian_put_u16(b []byte, v u16) {
+pub fn little_endian_put_u16(b mut []byte, v u16) {
 	_ := b[1] // bounds check
 	b[0] = byte(v)
 	b[1] = byte(v >> u16(8))
@@ -23,7 +23,7 @@ pub fn little_endian_u32(b []byte) u32 {
 	return u32(b[0]) | u32(u32(b[1])<<u32(8)) | u32(u32(b[2])<<u32(16)) | u32(u32(b[3])<<u32(24))
 }
 
-pub fn little_endian_put_u32(b []byte, v u32) {
+pub fn little_endian_put_u32(b mut []byte, v u32) {
 	_ := b[3] // bounds check
 	b[0] = byte(v)
 	b[1] = byte(v >> u32(8))
@@ -31,13 +31,13 @@ pub fn little_endian_put_u32(b []byte, v u32) {
 	b[3] = byte(v >> u32(24))
 }
 
-pub fn little_endian_u64(b []byte) u64 {
+pub fn little_endian_u64(b mut []byte) u64 {
 	_ := b[7] // bounds check
 	return u64(b[0]) | u64(u64(b[1])<<u64(8)) | u64(u64(b[2])<<u64(16)) | u64(u64(b[3])<<u64(24)) |
 		u64(u64(b[4])<<u64(32)) | u64(u64(b[5])<<u64(40)) | u64(u64(b[6])<<u64(48)) | u64(u64(b[7])<<u64(56))
 }
 
-pub fn little_endian_put_u64(b []byte, v u64) {
+pub fn little_endian_put_u64(b mut []byte, v u64) {
 	_ := b[7] // bounds check
 	b[0] = byte(v)
 	b[1] = byte(v >> u64(8))
@@ -55,18 +55,18 @@ pub fn big_endian_u16(b []byte) u16 {
 	return u16(b[1]) | u16(u16(b[0])<<u16(8))
 }
 
-pub fn big_endian_put_u16(b []byte, v u16) {
+pub fn big_endian_put_u16(b mut []byte, v u16) {
 	_ := b[1] // bounds check
 	b[0] = byte(v >> u16(8))
 	b[1] = byte(v)
 }
 
-pub fn big_endian_u32(b []byte) u32 {
+pub fn big_endian_u32(b  []byte) u32 {
 	_ := b[3] // bounds check
 	return u32(b[3]) | u32(u32(b[2])<<u32(8)) | u32(u32(b[1])<<u32(16)) | u32(u32(b[0])<<u32(24))
 }
 
-pub fn big_endian_put_u32(b []byte, v u32) {
+pub fn big_endian_put_u32(b mut []byte, v u32) {
 	_ := b[3] // bounds check
 	b[0] = byte(v >> u32(24))
 	b[1] = byte(v >> u32(16))
@@ -80,7 +80,7 @@ pub fn big_endian_u64(b []byte) u64 {
 		u64(u64(b[3])<<u64(32)) | u64(u64(b[2])<<u64(40)) | u64(u64(b[1])<<u64(48)) | u64(u64(b[0])<<u64(56))
 }
 
-pub fn big_endian_put_u64(b []byte, v u64) {
+pub fn big_endian_put_u64(b mut []byte, v u64) {
 	_ := b[7] // bounds check
 	b[0] = byte(v >> u64(56))
 	b[1] = byte(v >> u64(48))
diff --git a/vlib/gl/gl.v b/vlib/gl/gl.v
index 7dec8432d1..e7bbd6a105 100644
--- a/vlib/gl/gl.v
+++ b/vlib/gl/gl.v
@@ -179,7 +179,9 @@ pub fn gen_buffer() u32 {
 	return vbo 
 }
 
-pub fn vertex_attrib_pointer(index, size int, typ int, normalized bool, stride int, ptr int) {
+pub fn vertex_attrib_pointer(index, size int, typ int, normalized bool, _stride int, _ptr int) { 
+	mut stride := _stride 
+	mut ptr := _ptr 
 	if typ == GL_FLOAT {
 		stride *= sizeof(f32)
 		ptr *= sizeof(f32)
diff --git a/vlib/math/math.v b/vlib/math/math.v
index 3ffce42e6d..8d28530de9 100644
--- a/vlib/math/math.v
+++ b/vlib/math/math.v
@@ -134,6 +134,7 @@ pub fn exp2(a f64) f64 {
 
 // factorial calculates the factorial of the provided value.
 // TODO bring back once multiple value functions are implemented 
+/* 
 fn recursive_product( n int, current_number_ptr &int) int{
     mut m := n / 2
     if (m == 0){
@@ -174,6 +175,7 @@ pub fn factorial(n int) i64 {
     }
     return i64((r << shift))
 }
+*/ 
 
 // floor returns the nearest integer lower or equal of the provided value.
 pub fn floor(a f64) f64 {
@@ -191,7 +193,9 @@ pub fn gamma(a f64) f64 {
 }
 
 // gcd calculates greatest common (positive) divisor (or zero if a and b are both zero).
-pub fn gcd(a, b i64) i64 {
+pub fn gcd(a_, b_ i64) i64 {
+	mut a := a_ 
+	mut b := b_ 
 	if a < 0 {
 		a = -a
 	}
diff --git a/vlib/math/math_test.v b/vlib/math/math_test.v
index de45a0eda4..a76d187e44 100644
--- a/vlib/math/math_test.v
+++ b/vlib/math/math_test.v
@@ -27,11 +27,13 @@ fn test_digits() {
 	assert negative_digits[2] == -1
 }
 
+/* 
 fn test_factorial() {
 	assert math.factorial(12) == 479001600
 	assert math.factorial(5) == 120
 	assert math.factorial(0) == 1
 }
+*/ 
 
 fn test_erf() {
 	assert math.erf(0) == 0
diff --git a/vlib/net/urllib/urllib.v b/vlib/net/urllib/urllib.v
index 35f4c725c0..573d57f8aa 100644
--- a/vlib/net/urllib/urllib.v
+++ b/vlib/net/urllib/urllib.v
@@ -142,7 +142,8 @@ pub fn path_unescape(s string) ?string {
 
 // unescape unescapes a string; the mode specifies
 // which section of the URL string is being unescaped.
-fn unescape(s string, mode EncodingMode) ?string {
+fn unescape(s_ string, mode EncodingMode) ?string {
+	mut s := s_ 
 	// Count %, check that they're well-formed.
 	mut n := 0
 	mut has_plus := false
@@ -628,8 +629,9 @@ fn parse_host(host string) ?string {
 	h := unescape(host, .encode_host) or {
 		return err
 	}
-	host = h
-	return host
+	return h 
+	//host = h
+	//return host
 }
 
 // set_path sets the path and raw_path fields of the URL based on the provided
@@ -640,7 +642,7 @@ fn parse_host(host string) ?string {
 // - set_path('/foo%2fbar') will set path='/foo/bar' and raw_path='/foo%2fbar'
 // set_path will return an error only if the provided path contains an invalid
 // escaping.
-fn (u &URL) set_path(p string) ?bool {
+fn (u mut URL) set_path(p string) ?bool {
 	path := unescape(p, .encode_path) or {
 		return error(err)
 	}