diff --git a/vlib/builtin/string_interpolation.v b/vlib/builtin/string_interpolation.v
index c6176eec2d..2331956e6d 100644
--- a/vlib/builtin/string_interpolation.v
+++ b/vlib/builtin/string_interpolation.v
@@ -212,38 +212,45 @@ fn (data &StrIntpData) process_str_intp_data(mut sb strings.Builder) {
 	unsafe {
 		// strings
 		if typ == .si_s {
-			mut s := ''
 			if upper_case {
-				s = data.d.d_s.to_upper()
+				s := data.d.d_s.to_upper()
+				if width == 0 {
+					sb.write_string(s)
+				} else {
+					strconv.format_str_sb(s, bf, mut sb)
+				}
+				s.free()
 			} else {
-				s = data.d.d_s.clone()
+				if width == 0 {
+					sb.write_string(data.d.d_s)
+				} else {
+					strconv.format_str_sb(data.d.d_s, bf, mut sb)
+				}
 			}
-			if width == 0 {
-				sb.write_string(s)
-			} else {
-				strconv.format_str_sb(s, bf, mut sb)
-			}
-			s.free()
 			return
 		}
 
 		if typ == .si_r {
 			if width > 0 {
-				mut s := ''
 				if upper_case {
-					s = data.d.d_s.to_upper()
+					s := data.d.d_s.to_upper()
+					for _ in 1 .. (1 + (if width > 0 {
+						width
+					} else {
+						0
+					})) {
+						sb.write_string(s)
+					}
+					s.free()
 				} else {
-					s = data.d.d_s.clone()
+					for _ in 1 .. (1 + (if width > 0 {
+						width
+					} else {
+						0
+					})) {
+						sb.write_string(data.d.d_s)
+					}
 				}
-
-				for _ in 1 .. (1 + (if width > 0 {
-					width
-				} else {
-					0
-				})) {
-					sb.write_string(s)
-				}
-				s.free()
 			}
 			return
 		}
diff --git a/vlib/strings/builder.c.v b/vlib/strings/builder.c.v
index 93cbba8261..84f1af1f56 100644
--- a/vlib/strings/builder.c.v
+++ b/vlib/strings/builder.c.v
@@ -65,11 +65,13 @@ pub fn (mut b Builder) clear() {
 }
 
 // write_u8 appends a single `data` byte to the accumulated buffer
+@[inline]
 pub fn (mut b Builder) write_u8(data u8) {
 	b << data
 }
 
 // write_byte appends a single `data` byte to the accumulated buffer
+@[inline]
 pub fn (mut b Builder) write_byte(data u8) {
 	b << data
 }
diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index 60c6691aef..5cb41fef2f 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -676,9 +676,10 @@ pub fn (t &Table) sym_by_idx(idx int) &TypeSymbol {
 	return t.type_symbols[idx]
 }
 
+@[direct_array_access]
 pub fn (t &Table) sym(typ Type) &TypeSymbol {
 	idx := typ.idx()
-	if idx > 0 {
+	if idx > 0 && idx < t.type_symbols.len {
 		return t.type_symbols[idx]
 	}
 	// this should never happen
@@ -688,10 +689,10 @@ pub fn (t &Table) sym(typ Type) &TypeSymbol {
 }
 
 // final_sym follows aliases until it gets to a "real" Type
-@[inline]
+@[direct_array_access]
 pub fn (t &Table) final_sym(typ Type) &TypeSymbol {
 	mut idx := typ.idx()
-	if idx > 0 {
+	if idx > 0 && idx < t.type_symbols.len {
 		cur_sym := t.type_symbols[idx]
 		if cur_sym.info is Alias {
 			idx = cur_sym.info.parent_type.idx()
diff --git a/vlib/v/ast/types.v b/vlib/v/ast/types.v
index 79e2d6db06..9130e9995f 100644
--- a/vlib/v/ast/types.v
+++ b/vlib/v/ast/types.v
@@ -312,7 +312,7 @@ pub fn (t Type) nr_muls() int {
 pub fn (t Type) is_ptr() bool {
 	// any normal pointer, i.e. &Type, &&Type etc;
 	// Note: voidptr, charptr and byteptr are NOT included!
-	return (int(t) >> 16) & 0xff > 0
+	return (int(t) >> 16) & 0xff != 0
 }
 
 // is_pointer returns true if `typ` is any of the builtin pointer types (voidptr, byteptr, charptr)
@@ -331,7 +331,7 @@ pub fn (typ Type) is_voidptr() bool {
 // is_any_kind_of_pointer returns true if t is any type of pointer
 @[inline]
 pub fn (t Type) is_any_kind_of_pointer() bool {
-	return (int(t) >> 16) & 0xff > 0 || (u16(t) & 0xffff) in ast.pointer_type_idxs
+	return (int(t) >> 16) & 0xff != 0 || (u16(t) & 0xffff) in ast.pointer_type_idxs
 }
 
 // set nr_muls on `t` and return it
@@ -398,7 +398,7 @@ pub fn (t Type) clear_option_and_result() Type {
 // return true if `flag` is set on `t`
 @[inline]
 pub fn (t Type) has_flag(flag TypeFlag) bool {
-	return int(t) & (1 << (int(flag) + 24)) > 0
+	return int(t) & (1 << (int(flag) + 24)) != 0
 }
 
 @[inline]
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index bd02219e37..4d4f305a71 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -1437,8 +1437,10 @@ fn (mut c Checker) selector_expr(mut node ast.SelectorExpr) ast.Type {
 
 	using_new_err_struct_save := c.using_new_err_struct
 	// TODO: remove; this avoids a breaking change in syntax
-	if '${node.expr}' == 'err' {
-		c.using_new_err_struct = true
+	if node.expr is ast.Ident {
+		if node.expr.str() == 'err' {
+			c.using_new_err_struct = true
+		}
 	}
 
 	// T.name, typeof(expr).name
@@ -1545,7 +1547,7 @@ fn (mut c Checker) selector_expr(mut node ast.SelectorExpr) ast.Type {
 			return ast.u32_type
 		}
 	}
-	mut unknown_field_msg := 'type `${sym.name}` has no field named `${field_name}`'
+	mut unknown_field_msg := ''
 	mut has_field := false
 	mut field := ast.StructField{}
 	if field_name.len > 0 && field_name[0].is_capital() && sym.info is ast.Struct
@@ -1698,6 +1700,9 @@ fn (mut c Checker) selector_expr(mut node ast.SelectorExpr) ast.Type {
 			c.error('`${unwrapped_sym.name}` has no property `${node.field_name}`', node.pos)
 		}
 	} else {
+		if unknown_field_msg == '' {
+			unknown_field_msg = 'type `${sym.name}` has no field named `${field_name}`'
+		}
 		if sym.info is ast.Struct {
 			if c.smartcast_mut_pos != token.Pos{} {
 				c.note('smartcasting requires either an immutable value, or an explicit mut keyword before the value',
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index f4d3083e55..69a2081d49 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -2650,7 +2650,7 @@ fn cescape_nonascii(original string) string {
 			write_octal_escape(mut b, c)
 			continue
 		}
-		b.write_u8(c)
+		b << c
 	}
 	res := b.str()
 	return res
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index c8a6acb5af..c437bc54a9 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -890,7 +890,7 @@ fn (mut g Gen) call_expr(node ast.CallExpr) {
 		}
 	}
 	if node.is_method && !node.is_field {
-		if node.name == 'writeln' && g.pref.experimental && node.args.len > 0
+		if g.pref.experimental && node.args.len > 0 && node.name == 'writeln'
 			&& node.args[0].expr is ast.StringInterLiteral
 			&& g.table.sym(node.receiver_type).name == 'strings.Builder' {
 			g.string_inter_literal_sb_optimized(node)
diff --git a/vlib/v/gen/c/str.v b/vlib/v/gen/c/str.v
index 803ee873b9..4483b12e92 100644
--- a/vlib/v/gen/c/str.v
+++ b/vlib/v/gen/c/str.v
@@ -8,9 +8,13 @@ import v.util
 fn (mut g Gen) string_literal(node ast.StringLiteral) {
 	escaped_val := cescape_nonascii(util.smart_quote(node.val, node.is_raw))
 	if node.language == .c {
-		g.write('"${escaped_val}"')
+		g.write('"')
+		g.write(escaped_val)
+		g.write('"')
 	} else {
-		g.write('_SLIT("${escaped_val}")')
+		g.write('_SLIT("')
+		g.write(escaped_val)
+		g.write('")')
 	}
 }
 
@@ -149,7 +153,8 @@ fn (mut g Gen) gen_expr_to_string(expr ast.Expr, etype ast.Type) {
 				g.write(') ? _SLIT("nil") : ')
 			}
 		}
-		g.write('${str_fn_name}(')
+		g.write(str_fn_name)
+		g.write('(')
 		if str_method_expects_ptr && !is_ptr {
 			if is_dump_expr || (g.pref.ccompiler_type != .tinyc && expr is ast.CallExpr) {
 				g.write('ADDR(${g.typ(typ)}, ')
diff --git a/vlib/v/gen/c/str_intp.v b/vlib/v/gen/c/str_intp.v
index fb2323515a..bf74ef2be6 100644
--- a/vlib/v/gen/c/str_intp.v
+++ b/vlib/v/gen/c/str_intp.v
@@ -261,14 +261,18 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 			}
 		}
 	}
-	g.write(' str_intp(${node.vals.len}, ')
+	g.write(' str_intp(')
+	g.write(node.vals.len.str())
+	g.write(', ')
 	g.write('_MOV((StrIntpData[]){')
 	for i, val in node.vals {
 		mut escaped_val := cescape_nonascii(util.smart_quote(val, false))
 		escaped_val = escaped_val.replace('\0', '\\0')
 
 		if escaped_val.len > 0 {
-			g.write('{_SLIT("${escaped_val}"), ')
+			g.write('{_SLIT("')
+			g.write(escaped_val)
+			g.write('"), ')
 		} else {
 			g.write('{_SLIT0, ')
 		}
@@ -280,7 +284,11 @@ fn (mut g Gen) string_inter_literal(node ast.StringInterLiteral) {
 		}
 
 		ft_u64, ft_str := g.str_format(node, i, fmts)
-		g.write('0x${ft_u64.hex()}, {.d_${ft_str} = ')
+		g.write('0x')
+		g.write(ft_u64.hex())
+		g.write(', {.d_')
+		g.write(ft_str)
+		g.write(' = ')
 
 		// for pointers we need a void* cast
 		if unsafe { ft_str.str[0] } == `p` {
diff --git a/vlib/v/util/util.v b/vlib/v/util/util.v
index 8a16d11692..eb7f4be57b 100644
--- a/vlib/v/util/util.v
+++ b/vlib/v/util/util.v
@@ -16,7 +16,7 @@ import runtime
 // math.bits is needed by strconv.ftoa
 pub const builtin_module_parts = ['math.bits', 'strconv', 'dlmalloc', 'strconv.ftoa', 'strings',
 	'builtin']
-pub const bundle_modules = ['clipboard', 'fontstash', 'gg', 'gx', 'sokol', 'szip', 'ui']
+pub const bundle_modules = ['clipboard', 'fontstash', 'gg', 'gx', 'sokol', 'szip', 'ui']!
 
 pub const external_module_dependencies_for_tool = {
 	'vdoc': ['markdown']
@@ -34,7 +34,7 @@ const const_tabs = [
 	'\t\t\t\t\t\t\t\t',
 	'\t\t\t\t\t\t\t\t\t',
 	'\t\t\t\t\t\t\t\t\t\t',
-]
+]!
 
 pub const nr_jobs = runtime.nr_jobs()
 
@@ -42,8 +42,9 @@ pub fn module_is_builtin(mod string) bool {
 	return mod in util.builtin_module_parts
 }
 
+@[direct_array_access]
 pub fn tabs(n int) string {
-	return if n < util.const_tabs.len { util.const_tabs[n] } else { '\t'.repeat(n) }
+	return if n >= 0 && n < util.const_tabs.len { util.const_tabs[n] } else { '\t'.repeat(n) }
 }
 
 //