diff --git a/vlib/builtin/builtin_nix.c.v b/vlib/builtin/builtin_nix.c.v
index eb38d53b6b..6648e3e3f6 100644
--- a/vlib/builtin/builtin_nix.c.v
+++ b/vlib/builtin/builtin_nix.c.v
@@ -88,7 +88,7 @@ fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
 		return false
 	}
 	buffer := [100]byteptr{}
-	nr_ptrs := C.backtrace(buffer, 100)
+	nr_ptrs := C.backtrace(voidptr(buffer), 100)
 	if nr_ptrs < 2 {
 		eprintln('C.backtrace returned less than 2 frames')
 		return false
@@ -96,7 +96,7 @@ fn print_backtrace_skipping_top_frames_linux(skipframes int) bool {
 	nr_actual_frames := nr_ptrs - skipframes
 	mut sframes := []string{}
 	//////csymbols := backtrace_symbols(*voidptr(&buffer[skipframes]), nr_actual_frames)
-	csymbols := C.backtrace_symbols(&buffer[skipframes], nr_actual_frames)
+	csymbols := C.backtrace_symbols(voidptr(&buffer[skipframes]), nr_actual_frames)
 	for i in 0 .. nr_actual_frames {
 		sframes << unsafe {tos2( byteptr(csymbols[i]) )}
 	}
diff --git a/vlib/builtin/map.v b/vlib/builtin/map.v
index 89416b0c68..33bb510151 100644
--- a/vlib/builtin/map.v
+++ b/vlib/builtin/map.v
@@ -153,7 +153,7 @@ fn (d DenseArray) get(i int) voidptr {
 fn (mut d DenseArray) zeros_to_end() {
 	mut tmp_value := malloc(d.value_bytes)
 	mut count := u32(0)
-	for i in 0 .. d.len {
+	for i in 0 .. int(d.len) {
 		if unsafe {d.keys[i]}.str != 0 {
 			// swap keys
 			unsafe {
diff --git a/vlib/builtin/option.v b/vlib/builtin/option.v
index 3c33c850d3..95f0c01945 100644
--- a/vlib/builtin/option.v
+++ b/vlib/builtin/option.v
@@ -19,7 +19,7 @@ struct OptionBase {
 	ecode   int
 
 	// Data is trailing after ecode
-	// and is not included in here but in the 
+	// and is not included in here but in the
 	// derived Option_xxx types
 }
 
@@ -51,13 +51,11 @@ struct Option {
 	is_none bool
 	error   string
 	ecode   int
-
-	data    [400]byte
 }
 
 pub fn (o Option) str() string {
    if o.ok && !o.is_none {
-	  return 'Option{ data: ' + o.data[0..32].hex() + ' }'
+	  return 'Option{ ok }'
    }
    if o.is_none {
 	  return 'Option{ none }'
@@ -65,20 +63,6 @@ pub fn (o Option) str() string {
    return 'Option{ error: "${o.error}" }'
 }
 
-// `fn foo() ?Foo { return foo }` => `fn foo() ?Foo { return opt_ok(foo); }`
-fn opt_ok(data voidptr, size int) Option {
-	if size >= 400 {
-		panic('option size too big: $size (max is 400), this is a temporary limit')
-	}
-	res := Option{
-		ok: true
-	}
-	unsafe {
-		C.memcpy(res.data, data, size)
-	}
-	return res
-}
-
 // used internally when returning `none`
 fn opt_none() Option {
 	return Option{
diff --git a/vlib/os/file.v b/vlib/os/file.v
index 6ba940dcc0..08ac6a4970 100644
--- a/vlib/os/file.v
+++ b/vlib/os/file.v
@@ -142,7 +142,7 @@ pub fn (mut f File) get_line() ?string {
 		mut zblen := size_t(0)
 		mut zx := 0
 		unsafe {
-			zx = C.getline(&zbuf, &zblen, f.cfile)
+			zx = C.getline(&charptr(&zbuf), &zblen, f.cfile)
 			if zx == -1 {
 				C.free(zbuf)
 				if C.errno == 0 {
@@ -160,7 +160,7 @@ pub fn (mut f File) get_line() ?string {
 	//
 	buf := [4096]byte{}
 	mut res := strings.new_builder(1024)
-	mut x := 0
+	mut x := charptr(0)
 	for {
 		unsafe {
 			x = C.fgets(charptr(buf), 4096, f.cfile)
diff --git a/vlib/os/os_nix.c.v b/vlib/os/os_nix.c.v
index 97cbdd758d..7c44662ea6 100644
--- a/vlib/os/os_nix.c.v
+++ b/vlib/os/os_nix.c.v
@@ -252,7 +252,7 @@ pub fn is_writable_folder(folder string) ?bool {
 	}
 	tmp_perm_check := os.join_path(folder, 'XXXXXX')
 	unsafe {
-		x := C.mkstemp(tmp_perm_check.str)
+		x := C.mkstemp(charptr(tmp_perm_check.str))
 		if -1 == x {
 			return error('folder `$folder` is not writable')
 		}
diff --git a/vlib/strconv/format.v b/vlib/strconv/format.v
index 7af346a90b..2f2cffbccf 100644
--- a/vlib/strconv/format.v
+++ b/vlib/strconv/format.v
@@ -439,7 +439,6 @@ pub fn v_sprintf(str string, pt ... voidptr) string{
 	mut len1         := -1               // decimal part for floats
 	def_len1         := 6                // default value for len1
 	mut pad_ch       := byte(` `)              // pad char
-	mut th_separator := false            // thousands separator flag
 
 	// prefix chars for Length field
 	mut ch1 := `0`  // +1 char if present else `0`
@@ -453,7 +452,6 @@ pub fn v_sprintf(str string, pt ... voidptr) string{
 			len0         = -1
 			len1         = -1
 			pad_ch       = ` `
-			th_separator = false
 			status = .norm_char
 			ch1 = `0`
 			ch2 = `0`
@@ -518,7 +516,6 @@ pub fn v_sprintf(str string, pt ... voidptr) string{
 				i++
 				continue
 			} else if ch == `'` {
-				th_separator = true
 				i++
 				continue
 			} else if ch == `.` && fc_ch1 >= `1` && fc_ch1 <= `9` {
diff --git a/vlib/time/parse.v b/vlib/time/parse.v
index 55fba7c77c..1bdf74074e 100644
--- a/vlib/time/parse.v
+++ b/vlib/time/parse.v
@@ -66,7 +66,7 @@ pub fn parse_iso8601(s string) ?Time {
 	offset_hour := 0
 	offset_min := 0
 	count := unsafe {C.sscanf(charptr(s.str), '%4d-%2d-%2d%c%2d:%2d:%2d.%6d%c%2d:%2d',
-		&year, &month, &day, &time_char, &hour, &minute, &second, &mic_second, &plus_min, &offset_hour,
+		&year, &month, &day, charptr(&time_char), &hour, &minute, &second, &mic_second, charptr(&plus_min), &offset_hour,
 		&offset_min)}
 	if count != 11 {
 		return error('Invalid 8601 format')
diff --git a/vlib/v/builder/cc.v b/vlib/v/builder/cc.v
index b847a6999e..f23f8858b6 100644
--- a/vlib/v/builder/cc.v
+++ b/vlib/v/builder/cc.v
@@ -76,6 +76,12 @@ fn (mut v Builder) find_win_cc() ? {
 	v.pref.ccompiler_type = pref.cc_from_string(v.pref.ccompiler)
 }
 
+fn (mut v Builder) show_c_compiler_output(res os.Result) {
+	println('======== C Compiler output ========')
+	println(res.output)
+	println('=================================')
+}
+
 fn (mut v Builder) post_process_c_compiler_output(res os.Result) {
 	if res.exit_code == 0 {
 		if v.pref.reuse_tmpc {
@@ -545,6 +551,9 @@ fn (mut v Builder) cc() {
 	}
 	diff := time.ticks() - ticks
 	v.timing_message('C ${ccompiler:3}', diff)
+	if v.pref.show_c_output {
+		v.show_c_compiler_output(res)
+	}
 	if res.exit_code == 127 {
 		// the command could not be found by the system
 		$if linux {
@@ -559,7 +568,9 @@ fn (mut v Builder) cc() {
 			'-----------------------------------------------------------\n' + 'Probably your C compiler is missing. \n' +
 			'Please reinstall it, or make it available in your PATH.\n\n' + missing_compiler_info())
 	}
-	v.post_process_c_compiler_output(res)
+	if !v.pref.show_c_output {
+		v.post_process_c_compiler_output(res)
+	}
 	// Print the C command
 	if v.pref.is_verbose {
 		println('$ccompiler took $diff ms')
diff --git a/vlib/v/builder/msvc.v b/vlib/v/builder/msvc.v
index 0ffe671353..a7bcf1b239 100644
--- a/vlib/v/builder/msvc.v
+++ b/vlib/v/builder/msvc.v
@@ -303,7 +303,11 @@ pub fn (mut v Builder) cc_msvc() {
 	}
 	diff := time.ticks() - ticks
 	v.timing_message('C msvc', diff)
-	v.post_process_c_compiler_output(res)
+	if v.pref.show_c_output {
+		v.show_c_compiler_output(res)
+	} else {
+		v.post_process_c_compiler_output(res)
+	}
 	// println(res)
 	// println('C OUTPUT:')
 	// Always remove the object file - it is completely unnecessary
diff --git a/vlib/v/gen/cgen.v b/vlib/v/gen/cgen.v
index 976c4c6523..4eae5c7169 100644
--- a/vlib/v/gen/cgen.v
+++ b/vlib/v/gen/cgen.v
@@ -1440,7 +1440,6 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 	// return;
 	// }
 	// int pos = *(int*)_t190.data;
-	mut gen_or := false
 	mut tmp_opt := ''
 	is_optional := g.pref.autofree &&
 		(assign_stmt.op in [.decl_assign, .assign]) && assign_stmt.left_types.len == 1 && assign_stmt.right[0] is
@@ -1453,7 +1452,6 @@ fn (mut g Gen) gen_assign_stmt(assign_stmt ast.AssignStmt) {
 			tmp_opt = g.new_tmp_var()
 			g.write('/*AF opt*/$styp $tmp_opt = ')
 			g.expr(assign_stmt.right[0])
-			gen_or = true
 			g.or_block(tmp_opt, call_expr.or_block, call_expr.return_type)
 			g.writeln('/*=============ret*/')
 			// if af && is_optional {
@@ -2128,7 +2126,11 @@ fn (mut g Gen) expr(node ast.Expr) {
 			g.write('))')
 		}
 		ast.CharLiteral {
-			g.write("'$node.val'")
+			if node.val == r'\`' {
+				g.write("'`'")
+			} else {
+				g.write("'$node.val'")
+			}
 		}
 		ast.AtExpr {
 			g.comp_at(node)
@@ -4662,7 +4664,7 @@ fn (mut g Gen) gen_array_sort(node ast.CallExpr) {
 	g.expr(node.left)
 	g.write('${deref}len, ')
 	g.expr(node.left)
-	g.writeln('${deref}element_size, $compare_fn);')
+	g.writeln('${deref}element_size, (int (*)(const void *, const void *))&$compare_fn);')
 }
 
 // `nums.filter(it % 2 == 0)`
@@ -5060,7 +5062,15 @@ fn c_name(name_ string) string {
 	return name
 }
 
-fn (mut g Gen) type_default(typ table.Type) string {
+fn (mut g Gen) type_default(typ_ table.Type) string {
+	typ := g.unwrap_generic(typ_)
+	if typ.has_flag(.optional) {
+		return '{0}'
+	}
+	// Always set pointers to 0
+	if typ.is_ptr() {
+		return '0'
+	}
 	sym := g.table.get_type_symbol(typ)
 	if sym.kind == .array {
 		elem_sym := g.typ(sym.array_info().elem_type)
@@ -5074,10 +5084,6 @@ fn (mut g Gen) type_default(typ table.Type) string {
 		value_type_str := g.typ(sym.map_info().value_type)
 		return 'new_map_1(sizeof($value_type_str))'
 	}
-	// Always set pointers to 0
-	if typ.is_ptr() {
-		return '0'
-	}
 	// User struct defined in another module.
 	// if typ.contains('__') {
 	if sym.kind == .struct_ {
@@ -5105,7 +5111,8 @@ fn (mut g Gen) type_default(typ table.Type) string {
 		else {}
 	}
 	return match sym.kind {
-		.interface_, .sum_type, .array_fixed { '{0}' }
+		.interface_, .sum_type, .array_fixed, .multi_return { '{0}' }
+		.alias { g.type_default((sym.info as table.Alias).parent_type) }
 		else { '0' }
 	}
 	// TODO this results in
diff --git a/vlib/v/gen/cheaders.v b/vlib/v/gen/cheaders.v
index 135519fc52..c572d75229 100644
--- a/vlib/v/gen/cheaders.v
+++ b/vlib/v/gen/cheaders.v
@@ -67,6 +67,10 @@ const (
 	#undef TCCSKIP
 	#define TCCSKIP(x)
 	// #include <byteswap.h>
+	#ifndef _WIN32
+		#include <execinfo.h>
+		int tcc_backtrace(const char *fmt, ...);
+	#endif
 #endif
 
 // for __offset_of
@@ -431,20 +435,7 @@ typedef double any_float;
 typedef unsigned char* byteptr;
 typedef void* voidptr;
 typedef char* charptr;
-typedef struct array array;
-typedef struct map map;
-typedef array array_int;
-typedef array array_f32;
-typedef array array_f64;
-typedef array array_u16;
-typedef array array_u32;
-typedef array array_u64;
-//typedef map map_int;
-//typedef map map_string;
-//typedef array array_string;
-//typedef array array_byte;
 typedef byte array_fixed_byte_300 [300];
-typedef byte array_fixed_byte_400 [400];
 
 typedef struct sync__Channel* chan;
 
diff --git a/vlib/v/gen/fn.v b/vlib/v/gen/fn.v
index 56f9914ee0..317df8e33e 100644
--- a/vlib/v/gen/fn.v
+++ b/vlib/v/gen/fn.v
@@ -158,6 +158,15 @@ fn (mut g Gen) gen_fn_decl(it ast.FnDecl, skip bool) {
 		// TODO: remove this, when g.write_autofree_stmts_when_needed works properly
 		g.autofree_scope_vars(it.body_pos.pos)
 	}
+	if it.return_type != table.void_type {
+		mut default_expr := g.type_default(it.return_type)
+		// TODO: perf?
+		if default_expr == '{0}' {
+			g.writeln('\treturn ($type_name)$default_expr;')
+		} else {
+			g.writeln('\treturn $default_expr;')
+		}
+	}
 	g.writeln('}')
 	g.defer_stmts = []
 	if g.pref.printfn_list.len > 0 && g.last_fn_c_name in g.pref.printfn_list {
@@ -240,15 +249,7 @@ fn (mut g Gen) fn_args(args []table.Param, is_variadic bool) ([]string, []string
 				g.definitions.write(')')
 			}
 		} else {
-			mut nr_muls := arg.typ.nr_muls()
 			s := arg_type_name + ' ' + caname
-			if arg.is_mut {
-				// mut arg needs one *
-				nr_muls = 1
-			}
-			// if nr_muls > 0 && !is_varg {
-			// s = arg_type_name + strings.repeat(`*`, nr_muls) + ' ' + caname
-			// }
 			g.write(s)
 			g.definitions.write(s)
 			fargs << caname
diff --git a/vlib/v/gen/str.v b/vlib/v/gen/str.v
index 34d81abcde..b72185bbfd 100644
--- a/vlib/v/gen/str.v
+++ b/vlib/v/gen/str.v
@@ -6,6 +6,10 @@ import v.ast
 import v.table
 import strings
 
+const (
+	invalid_escapes = ['(', '{', '$', '`', '.']
+)
+
 fn smart_quote(str string, raw bool) string {
 	len := str.len
 	if len == 0 {
@@ -14,6 +18,7 @@ fn smart_quote(str string, raw bool) string {
 	mut result := strings.new_builder(0)
 	mut pos := -1
 	mut last := ''
+	// TODO: This should be a single char?
 	mut next := ''
 	mut skip_next := false
 	for {
@@ -43,45 +48,43 @@ fn smart_quote(str string, raw bool) string {
 			toadd = '\\"'
 			current = ''
 		}
-		if raw && current == '\\' {
-			toadd = '\\\\'
-		}
-		// keep newlines in string
-		if current == '\n' {
-			toadd = '\\n'
-			current = ''
-		}
-		if current == '\r' && next == '\n' {
-			toadd = '\r\n'
-			current = ''
-			skip_next = true
-		}
-		// backslash
-		if !raw && current == '\\' {
-			// escaped backslash - keep as is
-			if next == '\\' {
+		if current == '\\' {
+			if raw {
 				toadd = '\\\\'
-				skip_next = true
-			}
-			// keep raw escape squence
-			else {
-				if next != '' {
+			} else {
+				// escaped backslash - keep as is
+				if next == '\\' {
+					toadd = '\\\\'
+					skip_next = true
+				} else if next != '' {
 					if raw {
 						toadd = '\\\\' + next
 						skip_next = true
 					}
-					// escape it
-					else {
+					// keep all valid escape sequences
+					else if next !in invalid_escapes {
 						toadd = '\\' + next
 						skip_next = true
+					} else {
+						toadd = next
+						skip_next = true
 					}
 				}
 			}
 		}
+		// keep newlines in string
+		if current == '\n' {
+			toadd = '\\n'
+			current = ''
+		} else if current == '\r' && next == '\n' {
+			toadd = '\r\n'
+			current = ''
+			skip_next = true
+		}
 		// Dolar sign
 		if !raw && current == '$' {
 			if last == '\\' {
-				toadd = '\\$'
+				toadd = r'\$'
 			}
 		}
 		// Windows style new line \r\n
diff --git a/vlib/v/parser/parser.v b/vlib/v/parser/parser.v
index 4eee4d451d..5cb75b82bb 100644
--- a/vlib/v/parser/parser.v
+++ b/vlib/v/parser/parser.v
@@ -922,6 +922,7 @@ pub fn (mut p Parser) parse_ident(language table.Language) ast.Ident {
 	} else {
 		p.error('unexpected token `$p.tok.lit`')
 	}
+	return ast.Ident{}
 }
 
 pub fn (mut p Parser) name_expr() ast.Expr {
diff --git a/vlib/v/pref/pref.v b/vlib/v/pref/pref.v
index b110438003..419ad90b06 100644
--- a/vlib/v/pref/pref.v
+++ b/vlib/v/pref/pref.v
@@ -73,6 +73,7 @@ pub mut:
 	is_debug            bool // false by default, turned on by -g or -cg, it tells v to pass -g to the C backend compiler.
 	is_vlines           bool // turned on by -g, false by default (it slows down .tmp.c generation slightly).
 	show_cc             bool // -showcc, print cc command
+	show_c_output       bool // -show-c-output, print all cc output even if the code was compiled correctly
 	// NB: passing -cg instead of -g will set is_vlines to false and is_debug to true, thus making v generate cleaner C files,
 	// which are sometimes easier to debug / inspect manually than the .tmp.c files by plain -g (when/if v line number generation breaks).
 	use_cache           bool // turns on v usage of the module cache to speed up compilation.
@@ -243,6 +244,9 @@ pub fn parse_args(args []string) (&Preferences, string) {
 			'-showcc' {
 				res.show_cc = true
 			}
+			'-show-c-output' {
+				res.show_c_output = true
+			}
 			'-experimental' {
 				res.experimental = true
 			}
@@ -253,9 +257,6 @@ pub fn parse_args(args []string) (&Preferences, string) {
 				res.prealloc = true
 				res.build_options << arg
 			}
-			'-keepc' {
-				eprintln('-keepc is deprecated. V always keeps the generated .tmp.c files now.')
-			}
 			'-parallel' {
 				res.is_parallel = true
 			}
diff --git a/vlib/v/table/atypes.v b/vlib/v/table/atypes.v
index 83928c9482..5b2703d142 100644
--- a/vlib/v/table/atypes.v
+++ b/vlib/v/table/atypes.v
@@ -865,7 +865,6 @@ pub fn (table &Table) type_to_str(t Type) string {
 				res += table.type_to_str(typ)
 			}
 			res += ')'
-			res = res
 		}
 		.void {
 			if t.has_flag(.optional) {