cgen: use *char in all functions with *char args to avoid warnings

compiler/fn.v

@@ -746,14 +746,17 @@ fn (p mut Parser) fn_args(f mut Fn) {
 
 // foo *(1, 2, 3, mut bar)*
 fn (p mut Parser) fn_call_args(f mut Fn) &Fn {
-	// p.gen('(')
 	// println('fn_call_args() name=$f.name args.len=$f.args.len')
 	// C func. # of args is not known
-	// if f.name.starts_with('c_') {
 	p.check(.lpar)
 	if f.is_c {
 		for p.tok != .rpar {
-			p.bool_expression()
+			ph := p.cgen.add_placeholder()
+			typ := p.bool_expression()
+			// Cast V byteptr to C char* (byte is unsigned in V, that led to C warnings)
+			if typ == 'byte*' {
+				p.cgen.set_placeholder(ph, '(char*)')
+			}	
 			if p.tok == .comma {
 				p.gen(', ')
 				p.check(.comma)

compiler/parser.v

@@ -3171,6 +3171,7 @@ fn (p mut Parser) switch_statement() {
 	}
 	p.cgen.start_tmp()
 	typ := p.bool_expression()
+	is_str := typ == 'string'
 	expr := p.cgen.end_tmp()
 	p.check(.lcbr)
 	mut i := 0
@@ -3198,13 +3199,16 @@ fn (p mut Parser) switch_statement() {
 		mut got_comma := false
 		for {
 			if got_comma {
-				p.gen(') ||  ')
+				if is_str {
+					p.gen(')')
+				}	
+				p.gen(' || ')
 			}
 			if typ == 'string' {
 				p.gen('string_eq($expr, ')
 			}
 			else {
-				p.gen('($expr == ')
+				p.gen('$expr == ')
 			}
 			if p.tok == .key_case || p.tok == .key_default {
 				p.check(p.tok)
@@ -3222,7 +3226,10 @@ fn (p mut Parser) switch_statement() {
 		else {
 			p.check(.arrow)
 		}
-		p.gen(')) {')
+		if is_str {
+			p.gen(')')
+		}
+		p.gen(') {')
 		p.genln('/* case */')
 		p.statements()
 		all_cases_return = all_cases_return && p.returns