diff --git a/cmd/tools/vtimeout_test.v b/cmd/tools/vtimeout_test.v
index c8704a9e5e..2e252d982e 100644
--- a/cmd/tools/vtimeout_test.v
+++ b/cmd/tools/vtimeout_test.v
@@ -1,3 +1,4 @@
+// vtest retry: 3
 import os
 import time
 
diff --git a/doc/docs.md b/doc/docs.md
index 24e98f1fab..f0bb2ae461 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -6138,6 +6138,10 @@ that are substituted at compile time:
 - `@BUILD_DATE` => replaced with the build date, for example '2024-09-13' .
 - `@BUILD_TIME` => replaced with the build time, for example '12:32:07' .
 - `@BUILD_TIMESTAMP` => replaced with the build timestamp, for example '1726219885' .
+- `@OS` => replaced with the OS type, for example 'linux' .
+- `@CCOMPILER` => replaced with the C compiler type, for example 'gcc' .
+- `@BACKEND` => replaced with current language backend, for example 'c' or 'golang' .
+- `@PLATFORM` => replaced with the platform type, for example 'amd64' .
 Note: `@BUILD_DATE`, `@BUILD_TIME`, `@BUILD_TIMESTAMP` represent times in the UTC timezone.
 By default, they are based on the current time of the compilation/build. They can be overridden
 by setting the environment variable `SOURCE_DATE_EPOCH`. That is also useful while making
diff --git a/vlib/flag/flag_to.v b/vlib/flag/flag_to.v
index 876d65d995..6baa1992d3 100644
--- a/vlib/flag/flag_to.v
+++ b/vlib/flag/flag_to.v
@@ -934,9 +934,7 @@ pub fn (fm FlagMapper) to_struct[T](defaults ?T) !T {
 						.f64()
 				} $else $if field.typ is bool {
 					if arg := f.arg {
-						if arg != '' {
-							return error('can not assign `${arg}` to bool field `${field.name}`')
-						}
+						return error('can not assign `${arg}` to bool field `${field.name}`')
 					}
 					result.$(field.name) = !the_default.$(field.name)
 				} $else $if field.typ is string {
@@ -1037,7 +1035,7 @@ fn (mut fm FlagMapper) map_v(flag_ctx FlagContext, field StructField) !bool {
 	next := flag_ctx.next
 
 	if field.hints.has(.is_bool) {
-		if flag_name == field.match_name {
+		if flag_name == field.match_name || flag_name == field.short {
 			arg := if flag_raw.contains('=') { flag_raw.all_after('=') } else { '' }
 			if arg != '' {
 				return error('flag `${flag_raw}` can not be assigned to bool field "${field.name}"')
diff --git a/vlib/flag/flag_to_tail_bool_test.v b/vlib/flag/flag_to_tail_bool_test.v
index a67e923f44..d28176c2ea 100644
--- a/vlib/flag/flag_to_tail_bool_test.v
+++ b/vlib/flag/flag_to_tail_bool_test.v
@@ -1,14 +1,16 @@
 import flag
 
-const args_bool_short = ['some.exe', '-h']
-const args_bool_long = ['some.exe', '-help']
-
 struct CliOptions {
 	show_help bool @[long: 'help'; short: h]
 }
 
-fn test_short_tail_bool() {
-	cli_options, unmatched := flag.to_struct[CliOptions](args_bool_short,
+struct CliOptions2 {
+	show_help bool @[long: 'help'; short: h]
+	long      string
+}
+
+fn test_v_style_short_tail_bool() {
+	cli_options, unmatched := flag.to_struct[CliOptions](['some.exe', '-h'],
 		skip:  1
 		style: .v
 		mode:  .relaxed
@@ -24,8 +26,8 @@ fn test_short_tail_bool() {
 	}
 }
 
-fn test_long_tail_bool() {
-	cli_options, unmatched := flag.to_struct[CliOptions](args_bool_long,
+fn test_v_style_long_tail_bool() {
+	cli_options, unmatched := flag.to_struct[CliOptions](['some.exe', '-help'],
 		skip:  1
 		style: .v
 		mode:  .relaxed
@@ -40,3 +42,39 @@ fn test_long_tail_bool() {
 		assert false
 	}
 }
+
+fn test_v_style_short_bool() {
+	cli_options, unmatched := flag.to_struct[CliOptions2](['some.exe', '-h', '-long', 'val'],
+		skip:  1
+		style: .v
+		mode:  .relaxed
+	)!
+
+	if unmatched.len > 0 {
+		assert false
+	}
+	if cli_options.show_help {
+		assert true
+	} else {
+		assert false
+	}
+	assert cli_options.long == 'val'
+}
+
+fn test_v_style_long_bool() {
+	cli_options, unmatched := flag.to_struct[CliOptions2](['some.exe', '-help', '-long', 'val'],
+		skip:  1
+		style: .v
+		mode:  .relaxed
+	)!
+
+	if unmatched.len > 0 {
+		assert false
+	}
+	if cli_options.show_help {
+		assert true
+	} else {
+		assert false
+	}
+	assert cli_options.long == 'val'
+}
diff --git a/vlib/net/tcp.c.v b/vlib/net/tcp.c.v
index 10dd28c54d..ca24b81b86 100644
--- a/vlib/net/tcp.c.v
+++ b/vlib/net/tcp.c.v
@@ -158,10 +158,13 @@ pub fn (c TcpConn) read_ptr(buf_ptr &u8, len int) !int {
 			-1
 		}
 	}
-	$if trace_tcp ? {
-		eprintln('<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} len: ${len} | res: ${res}')
-	}
+	ecode := error_code()
 	if res > 0 {
+		$if trace_tcp ? {
+			eprintln(
+				'<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} | len: ${len} | res: ${res} |\n' +
+				unsafe { buf_ptr.vstring_with_len(len) })
+		}
 		$if trace_tcp_data_read ? {
 			eprintln(
 				'<<< TcpConn.read_ptr  | 1 data.len: ${res:6} | hex: ${unsafe { buf_ptr.vbytes(res) }.hex()} | data: ' +
@@ -169,7 +172,7 @@ pub fn (c TcpConn) read_ptr(buf_ptr &u8, len int) !int {
 		}
 		return res
 	}
-	code := if should_ewouldblock { int(error_ewouldblock) } else { error_code() }
+	code := if should_ewouldblock { int(error_ewouldblock) } else { ecode }
 	if code in [int(error_ewouldblock), int(error_eagain), C.EINTR] {
 		c.wait_for_read()!
 		res = $if is_coroutine ? {
@@ -178,7 +181,9 @@ pub fn (c TcpConn) read_ptr(buf_ptr &u8, len int) !int {
 			C.recv(c.sock.handle, voidptr(buf_ptr), len, msg_dontwait)
 		}
 		$if trace_tcp ? {
-			eprintln('<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} len: ${len} | res: ${res}')
+			eprintln(
+				'<<< TcpConn.read_ptr  | c.sock.handle: ${c.sock.handle} | buf_ptr: ${ptr_str(buf_ptr)} | len: ${len} | res: ${res} | code: ${code} |\n' +
+				unsafe { buf_ptr.vstring_with_len(len) })
 		}
 		$if trace_tcp_data_read ? {
 			if res > 0 {
@@ -234,11 +239,11 @@ pub fn (mut c TcpConn) write_ptr(b &u8, len int) !int {
 			} $else {
 				C.send(c.sock.handle, ptr, remaining, msg_nosignal)
 			}
+			code := error_code()
 			$if trace_tcp_data_write ? {
 				eprintln('>>> TcpConn.write_ptr | data chunk, total_sent: ${total_sent:6}, remaining: ${remaining:6}, ptr: ${voidptr(ptr):x} => sent: ${sent:6}')
 			}
 			if sent < 0 {
-				code := error_code()
 				$if trace_tcp_send_failures ? {
 					eprintln('>>> TcpConn.write_ptr | send_failure, data.len: ${len:6}, total_sent: ${total_sent:6}, remaining: ${remaining:6}, ptr: ${voidptr(ptr):x}, c.write_timeout: ${c.write_timeout:3} => sent: ${sent:6}, error code: ${code:3}')
 				}
@@ -456,9 +461,8 @@ pub fn (mut l TcpListener) accept_only() !&TcpConn {
 	} $else {
 		C.accept(l.sock.handle, 0, 0)
 	}
-
+	code := error_code()
 	if !l.is_blocking && new_handle <= 0 {
-		code := error_code()
 		if code in [int(error_einprogress), int(error_ewouldblock), int(error_eagain), C.EINTR] {
 			l.wait_for_accept()!
 			new_handle = $if is_coroutine ? {
@@ -642,10 +646,10 @@ fn (mut s TcpSocket) connect(a Addr) ! {
 		} $else {
 			C.connect(s.handle, voidptr(&a), a.len())
 		}
+		ecode := error_code()
 		if res == 0 {
 			return
 		}
-		ecode := error_code()
 		// On nix non-blocking sockets we expect einprogress
 		// On windows we expect res == -1 && error_code() == ewouldblock
 		if (is_windows && ecode == int(error_ewouldblock)) || (!is_windows && res == -1
diff --git a/vlib/v/ast/table.v b/vlib/v/ast/table.v
index e6858794d9..3d01708eed 100644
--- a/vlib/v/ast/table.v
+++ b/vlib/v/ast/table.v
@@ -2190,16 +2190,15 @@ pub fn (mut t Table) unwrap_generic_type_ex(typ Type, generic_names []string, co
 		Interface {
 			// resolve generic types inside methods
 			mut imethods := ts.info.methods.clone()
+			gn_names := t.get_real_generic_names(typ, generic_names)
 			for mut method in imethods {
-				if unwrap_typ := t.convert_generic_type(method.return_type, generic_names,
-					concrete_types)
+				if unwrap_typ := t.convert_generic_type(method.return_type, gn_names,
+					concrete_types[..gn_names.len])
 				{
 					method.return_type = unwrap_typ
 				}
 				for mut param in method.params {
-					if unwrap_typ := t.convert_generic_type(param.typ, generic_names,
-						concrete_types)
-					{
+					if unwrap_typ := t.convert_generic_type(param.typ, gn_names, concrete_types) {
 						param.typ = unwrap_typ
 					}
 				}
@@ -2289,6 +2288,7 @@ pub fn (mut t Table) generic_insts_to_concrete() {
 									fields[i].typ = t.unwrap_generic_type(fields[i].typ,
 										generic_names, info.concrete_types)
 								}
+
 								if t_typ := t.convert_generic_type(fields[i].typ, generic_names,
 									info.concrete_types)
 								{
@@ -2464,6 +2464,18 @@ pub fn (mut t Table) generic_insts_to_concrete() {
 	}
 }
 
+// Extracts all generic names from Type<A>[B] => B when <A>[B] is present
+// otherwise generic_names is returned
+pub fn (t &Table) get_real_generic_names(typ Type, generic_names []string) []string {
+	if typ.has_flag(.generic) {
+		typ_name := t.type_to_str(typ)
+		if typ_name.contains('>[') {
+			return typ_name.split('>[')[1].all_before_last(']').split(',')
+		}
+	}
+	return generic_names
+}
+
 // Extracts all type names from given types, notice that MultiReturn will be decompose
 // and will not included in returned string
 pub fn (t &Table) get_generic_names(generic_types []Type) []string {
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index 0233816cef..3fccd9661b 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -4030,6 +4030,18 @@ fn (mut c Checker) at_expr(mut node ast.AtExpr) ast.Type {
 		.build_timestamp {
 			node.val = util.stable_build_time.unix().str()
 		}
+		.os {
+			node.val = pref.get_host_os().lower()
+		}
+		.ccompiler {
+			node.val = c.pref.ccompiler_type.str()
+		}
+		.backend {
+			node.val = c.pref.backend.str()
+		}
+		.platform {
+			node.val = c.pref.arch.str()
+		}
 		.unknown {
 			c.error('unknown @ identifier: ${node.name}. Available identifiers: ${token.valid_at_tokens}',
 				node.pos)
diff --git a/vlib/v/checker/fn.v b/vlib/v/checker/fn.v
index 69eff4fead..3b2b3aa245 100644
--- a/vlib/v/checker/fn.v
+++ b/vlib/v/checker/fn.v
@@ -1472,6 +1472,7 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 			node.pos)
 	}
 	mut has_decompose := false
+	mut nr_multi_values := 0
 	for i, mut call_arg in node.args {
 		if func.params.len == 0 {
 			continue
@@ -1482,21 +1483,22 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 		if !func.is_variadic && has_decompose {
 			c.error('cannot have parameter after array decompose', node.pos)
 		}
+		param_i := i + nr_multi_values
 		param := if func.is_variadic && i >= func.params.len - 1 {
 			func.params.last()
 		} else {
-			func.params[i]
+			func.params[param_i]
 		}
 		// registers if the arg must be passed by ref to disable auto deref args
 		call_arg.should_be_ptr = param.typ.is_ptr() && !param.is_mut
 		if func.is_variadic && call_arg.expr is ast.ArrayDecompose {
-			if i > func.params.len - 1 {
+			if param_i > func.params.len - 1 {
 				c.error('too many arguments in call to `${func.name}`', node.pos)
 			}
 		}
 		has_decompose = call_arg.expr is ast.ArrayDecompose
 		already_checked := node.language != .js && call_arg.expr is ast.CallExpr
-		if func.is_variadic && i >= func.params.len - 1 {
+		if func.is_variadic && param_i >= func.params.len - 1 {
 			param_sym := c.table.sym(param.typ)
 			mut expected_type := param.typ
 			if param_sym.info is ast.Array {
@@ -1688,15 +1690,16 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 					multi_param := if func.is_variadic && i >= func.params.len - 1 {
 						func.params.last()
 					} else {
-						func.params[n + i]
+						func.params[n + param_i]
 					}
 					c.check_expected_call_arg(curr_arg, c.unwrap_generic(multi_param.typ),
 						node.language, call_arg) or {
-						c.error('${err.msg()} in argument ${i + n + 1} to `${fn_name}` from ${c.table.type_to_str(arg_typ)}',
+						c.error('${err.msg()} in argument ${param_i + n + 1} to `${fn_name}` from ${c.table.type_to_str(arg_typ)}',
 							call_arg.pos)
 						continue out
 					}
 				}
+				nr_multi_values += arg_typ_sym.info.types.len - 1
 				continue
 			} else if param_typ_sym.info is ast.Struct && arg_typ_sym.info is ast.Struct
 				&& param_typ_sym.info.is_anon {
@@ -1788,13 +1791,14 @@ fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool) ast.
 				continue
 			}
 			*/
-			c.error('${err.msg()} in argument ${i + 1} to `${fn_name}`', call_arg.pos)
+			c.error('${err.msg()} in argument ${i + nr_multi_values + 1} to `${fn_name}`',
+				call_arg.pos)
 		}
 		if final_param_sym.kind == .struct && arg_typ !in [ast.voidptr_type, ast.nil_type]
 			&& !c.check_multiple_ptr_match(arg_typ, param.typ, param, call_arg) {
 			got_typ_str, expected_typ_str := c.get_string_names_of(arg_typ, param.typ)
-			c.error('cannot use `${got_typ_str}` as `${expected_typ_str}` in argument ${i + 1} to `${fn_name}`',
-				call_arg.pos)
+			c.error('cannot use `${got_typ_str}` as `${expected_typ_str}` in argument ${i +
+				nr_multi_values + 1} to `${fn_name}`', call_arg.pos)
 		}
 		// Warn about automatic (de)referencing, which will be removed soon.
 		if func.language != .c && !c.inside_unsafe && !(call_arg.is_mut && param.is_mut) {
@@ -2924,6 +2928,17 @@ fn (mut c Checker) check_expected_arg_count(mut node ast.CallExpr, f &ast.Fn) !
 				return error('')
 			}
 		}
+	} else if node.args.len > 1 && node.args.any(it.expr is ast.CallExpr
+		&& it.expr.nr_ret_values > 1) {
+		mut check_args := 0
+		for arg in node.args {
+			if arg.expr is ast.CallExpr && arg.expr.nr_ret_values > 0 {
+				check_args += arg.expr.nr_ret_values
+			} else {
+				check_args += 1
+			}
+		}
+		nr_args = check_args
 	}
 	if min_required_params < 0 {
 		min_required_params = 0
@@ -2966,7 +2981,7 @@ fn (mut c Checker) check_expected_arg_count(mut node ast.CallExpr, f &ast.Fn) !
 		)
 		return error('')
 	} else if !f.is_variadic && nr_args > nr_params {
-		unexpected_args_pos := node.args[min_required_params].pos.extend(node.args.last().pos)
+		unexpected_args_pos := node.args[int_min(min_required_params, node.args.len - 1)].pos.extend(node.args.last().pos)
 		// c.error('3expected ${min_required_params} arguments, but got ${nr_args}', unexpected_args_pos)
 		c.fn_call_error_have_want(
 			nr_params: min_required_params
diff --git a/vlib/v/checker/tests/multi_return_arg_missing_err.out b/vlib/v/checker/tests/multi_return_arg_missing_err.out
new file mode 100644
index 0000000000..bf1936a620
--- /dev/null
+++ b/vlib/v/checker/tests/multi_return_arg_missing_err.out
@@ -0,0 +1,18 @@
+vlib/v/checker/tests/multi_return_arg_missing_err.vv:12:14: error: expected 2 arguments, but got 3
+   10 | 
+   11 | fn main() {
+   12 |     expect_2(1, returning_2())
+      |                 ~~~~~~~~~~~~~
+   13 |     expect_2(returning_2(), 1)
+   14 |     expect_4(returning_2(), returning_2())
+Details: have (int literal, (int, int))
+         want (int, int)
+vlib/v/checker/tests/multi_return_arg_missing_err.vv:13:26: error: expected 2 arguments, but got 3
+   11 | fn main() {
+   12 |     expect_2(1, returning_2())
+   13 |     expect_2(returning_2(), 1)
+      |                             ^
+   14 |     expect_4(returning_2(), returning_2())
+   15 | }
+Details: have ((int, int), int literal)
+         want (int, int)
diff --git a/vlib/v/checker/tests/multi_return_arg_missing_err.vv b/vlib/v/checker/tests/multi_return_arg_missing_err.vv
new file mode 100644
index 0000000000..64a8db1a9f
--- /dev/null
+++ b/vlib/v/checker/tests/multi_return_arg_missing_err.vv
@@ -0,0 +1,15 @@
+fn expect_2(a int, b int) {
+}
+
+fn expect_4(a int, b int, c int, d int) {
+}
+
+fn returning_2() (int, int) {
+	return 1, 1
+}
+
+fn main() {
+	expect_2(1, returning_2())
+	expect_2(returning_2(), 1)
+	expect_4(returning_2(), returning_2())
+}
diff --git a/vlib/v/checker/tests/multi_return_err.out b/vlib/v/checker/tests/multi_return_err.out
index 86848492be..a16e11e40c 100644
--- a/vlib/v/checker/tests/multi_return_err.out
+++ b/vlib/v/checker/tests/multi_return_err.out
@@ -5,24 +5,20 @@ vlib/v/checker/tests/multi_return_err.vv:18:10: error: cannot use `f64` as `int`
       |             ~~~~~~~~~~
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
-vlib/v/checker/tests/multi_return_err.vv:19:2: error: expected 3 arguments, but got 2
+vlib/v/checker/tests/multi_return_err.vv:19:11: error: cannot use `f64` as `int` in argument 2 to `my_func3` from (int, f64)
    17 | fn main() {
    18 |     my_func(my_func2())
    19 |     my_func3(my_func2(), 'foo')
-      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+      |              ~~~~~~~~~~
    20 |     my_func4('foo', my_func2())
    21 |     my_func(my_func5())
-Details: have ((int, f64), string)
-         want (int, int, string)
-vlib/v/checker/tests/multi_return_err.vv:20:2: error: expected 3 arguments, but got 2
+vlib/v/checker/tests/multi_return_err.vv:20:18: error: cannot use `f64` as `int` in argument 3 to `my_func4` from (int, f64)
    18 |     my_func(my_func2())
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
-      |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+      |                     ~~~~~~~~~~
    21 |     my_func(my_func5())
    22 |     my_func(my_func6())
-Details: have (string, (int, f64))
-         want (string, int, int)
 vlib/v/checker/tests/multi_return_err.vv:21:2: error: expected 2 arguments, but got 1
    19 |     my_func3(my_func2(), 'foo')
    20 |     my_func4('foo', my_func2())
diff --git a/vlib/v/fmt/tests/import_duplicate_input.vv b/vlib/v/fmt/tests/import_duplicate_input.vv
deleted file mode 100644
index 2d248cb482..0000000000
--- a/vlib/v/fmt/tests/import_duplicate_input.vv
+++ /dev/null
@@ -1,18 +0,0 @@
-import math
-import os
-import math
-// keep comment
-import gg
-import gg { MouseButton }
-import time { Duration }
-import time { Duration }
-import math.complex { Complex }
-import math.complex { Complex }
-
-const mypi = math.pi
-const mb = MouseButton{}
-const complex = Complex{}
-
-fn main() {
-	println(os.path_separator)
-}
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index e03e10d3a0..79cd19c325 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -1107,6 +1107,7 @@ pub fn (mut g Gen) get_sumtype_variant_name(typ ast.Type, sym ast.TypeSymbol) st
 pub fn (mut g Gen) write_typeof_functions() {
 	g.writeln('')
 	g.writeln('// >> typeof() support for sum types / interfaces')
+	mut already_generated_ifaces := map[string]bool{}
 	for ityp, sym in g.table.type_symbols {
 		if sym.kind == .sum_type {
 			if g.pref.skip_unused && sym.idx !in g.table.used_features.used_syms {
@@ -1177,6 +1178,10 @@ pub fn (mut g Gen) write_typeof_functions() {
 			if g.pref.skip_unused && sym.idx !in g.table.used_features.used_syms {
 				continue
 			}
+			if sym.cname in already_generated_ifaces {
+				continue
+			}
+			already_generated_ifaces[sym.cname] = true
 			g.definitions.writeln('${g.static_non_parallel}char * v_typeof_interface_${sym.cname}(int sidx);')
 			if g.pref.parallel_cc {
 				g.extern_out.writeln('extern char * v_typeof_interface_${sym.cname}(int sidx);')
@@ -1805,11 +1810,15 @@ static inline void __${sym.cname}_pushval(${sym.cname} ch, ${push_arg} val) {
 			interface_non_generic_syms << sym
 		}
 	}
+	mut already_generated_ifaces := map[string]bool{}
 	for sym in interface_non_generic_syms {
 		if g.pref.skip_unused && sym.idx !in g.table.used_features.used_syms {
 			continue
 		}
-		g.write_interface_typesymbol_declaration(sym)
+		if sym.cname !in already_generated_ifaces {
+			g.write_interface_typesymbol_declaration(sym)
+			already_generated_ifaces[sym.cname] = true
+		}
 	}
 }
 
@@ -7859,6 +7868,7 @@ fn (mut g Gen) interface_table() string {
 	}
 	mut sb := strings.new_builder(100)
 	mut conversion_functions := strings.new_builder(100)
+	mut already_generated_ifaces := map[string]bool{}
 	interfaces := g.table.type_symbols.filter(it.kind == .interface && it.info is ast.Interface)
 	for isym in interfaces {
 		inter_info := isym.info as ast.Interface
@@ -7868,6 +7878,10 @@ fn (mut g Gen) interface_table() string {
 		if g.pref.skip_unused && isym.idx !in g.table.used_features.used_syms {
 			continue
 		}
+		if isym.cname in already_generated_ifaces {
+			continue
+		}
+		already_generated_ifaces[isym.cname] = true
 		// interface_name is for example Speaker
 		interface_name := isym.cname
 		// generate a struct that references interface methods
diff --git a/vlib/v/markused/walker.v b/vlib/v/markused/walker.v
index a2156e7a49..a7a286a72b 100644
--- a/vlib/v/markused/walker.v
+++ b/vlib/v/markused/walker.v
@@ -432,6 +432,9 @@ fn (mut w Walker) expr(node_ ast.Expr) {
 			if !w.uses_array && !w.is_direct_array_access {
 				w.uses_array = true
 			}
+			if node.elem_type.has_flag(.option) {
+				w.used_option++
+			}
 		}
 		ast.Assoc {
 			w.exprs(node.exprs)
@@ -1180,6 +1183,9 @@ pub fn (mut w Walker) mark_by_sym(isym ast.TypeSymbol) {
 			w.mark_by_type(isym.info.key_type)
 			w.mark_by_type(isym.info.value_type)
 			w.features.used_maps++
+			if isym.info.value_type.has_flag(.option) {
+				w.used_option++
+			}
 		}
 		ast.Alias {
 			w.mark_by_type(isym.info.parent_type)
@@ -1295,9 +1301,6 @@ fn (mut w Walker) mark_resource_dependencies() {
 		w.fn_by_name('strings.new_builder')
 		w.uses_free[ast.string_type] = true
 	}
-	if w.uses_eq {
-		w.fn_by_name('fast_string_eq')
-	}
 	if w.features.auto_str_ptr {
 		w.fn_by_name('isnil')
 		w.fn_by_name('tos4')
@@ -1594,6 +1597,9 @@ pub fn (mut w Walker) finalize(include_panic_deps bool) {
 		w.mark_by_sym_name('StrIntpData')
 		w.mark_by_sym_name('StrIntpMem')
 	}
+	if w.uses_eq {
+		w.fn_by_name('fast_string_eq')
+	}
 
 	// remove unused symbols
 	w.remove_unused_fn_generic_types()
diff --git a/vlib/v/parser/comptime.v b/vlib/v/parser/comptime.v
index 33e2bc2207..67ca8dfd4f 100644
--- a/vlib/v/parser/comptime.v
+++ b/vlib/v/parser/comptime.v
@@ -511,6 +511,10 @@ fn (mut p Parser) at() ast.AtExpr {
 		'@BUILD_DATE' { token.AtKind.build_date }
 		'@BUILD_TIME' { token.AtKind.build_time }
 		'@BUILD_TIMESTAMP' { token.AtKind.build_timestamp }
+		'@OS' { token.AtKind.os }
+		'@CCOMPILER' { token.AtKind.ccompiler }
+		'@BACKEND' { token.AtKind.backend }
+		'@PLATFORM' { token.AtKind.platform }
 		else { token.AtKind.unknown }
 	}
 	expr := ast.AtExpr{
diff --git a/vlib/v/parser/module.v b/vlib/v/parser/module.v
index 69df3d099f..472b7e7c2e 100644
--- a/vlib/v/parser/module.v
+++ b/vlib/v/parser/module.v
@@ -310,6 +310,11 @@ fn (mut p Parser) import_syms(mut parent ast.Import) {
 	for p.tok.kind == .name {
 		pos := p.tok.pos()
 		alias := p.check_name()
+		if alias in p.imported_symbols {
+			p.error_with_pos('cannot register symbol `${alias}`, it was already imported',
+				pos)
+			return
+		}
 		p.imported_symbols[alias] = parent.mod + '.' + alias
 		// so we can work with this in fmt+checker
 		parent.syms << ast.ImportSymbol{
diff --git a/vlib/v/parser/tests/module_import_same_symbol2_err.out b/vlib/v/parser/tests/module_import_same_symbol2_err.out
new file mode 100644
index 0000000000..db6ba12a74
--- /dev/null
+++ b/vlib/v/parser/tests/module_import_same_symbol2_err.out
@@ -0,0 +1,3 @@
+vlib/v/parser/tests/module_import_same_symbol2_err.vv:1:20: error: cannot register symbol `max`, it was already imported
+    1 | import math { max, max }
+      |                    ~~~
diff --git a/vlib/v/parser/tests/module_import_same_symbol2_err.vv b/vlib/v/parser/tests/module_import_same_symbol2_err.vv
new file mode 100644
index 0000000000..9a6c870663
--- /dev/null
+++ b/vlib/v/parser/tests/module_import_same_symbol2_err.vv
@@ -0,0 +1 @@
+import math { max, max }
diff --git a/vlib/v/parser/tests/module_import_same_symbol_err.out b/vlib/v/parser/tests/module_import_same_symbol_err.out
new file mode 100644
index 0000000000..1f2a754a02
--- /dev/null
+++ b/vlib/v/parser/tests/module_import_same_symbol_err.out
@@ -0,0 +1,4 @@
+vlib/v/parser/tests/module_import_same_symbol_err.vv:2:17: error: cannot register symbol `max`, it was already imported
+    1 | import math { max }
+    2 | import arrays { max }
+      |                 ~~~
diff --git a/vlib/v/parser/tests/module_import_same_symbol_err.vv b/vlib/v/parser/tests/module_import_same_symbol_err.vv
new file mode 100644
index 0000000000..88bcf786e9
--- /dev/null
+++ b/vlib/v/parser/tests/module_import_same_symbol_err.vv
@@ -0,0 +1,2 @@
+import math { max }
+import arrays { max }
diff --git a/vlib/v/scanner/tests/unknown_comptime_var_err.out b/vlib/v/scanner/tests/unknown_comptime_var_err.out
index 3c2f9df3da..861ea2e093 100644
--- a/vlib/v/scanner/tests/unknown_comptime_var_err.out
+++ b/vlib/v/scanner/tests/unknown_comptime_var_err.out
@@ -5,4 +5,5 @@ vlib/v/scanner/tests/unknown_comptime_var_err.vv:2:9: error: @ must be used befo
     3 | }
 Details: available compile time variables: @VROOT, @VMODROOT, @VEXEROOT, @FN, @METHOD, @MOD,
 @STRUCT, @VEXE, @FILE, @DIR, @LINE, @COLUMN, @VHASH, @VCURRENTHASH, @VMOD_FILE, @VMODHASH,
-@FILE_LINE, @LOCATION, @BUILD_DATE, @BUILD_TIME, @BUILD_TIMESTAMP
+@FILE_LINE, @LOCATION, @BUILD_DATE, @BUILD_TIME, @BUILD_TIMESTAMP, @OS, @CCOMPILER,
+@BACKEND, @PLATFORM
diff --git a/vlib/v/tests/comptime/comptime_at_test.v b/vlib/v/tests/comptime/comptime_at_test.v
index a6a761bc39..eb680717c8 100644
--- a/vlib/v/tests/comptime/comptime_at_test.v
+++ b/vlib/v/tests/comptime/comptime_at_test.v
@@ -198,3 +198,27 @@ fn test_at_build_date_time_timestamp() {
 	now_utc := dump(time.utc().unix())
 	assert now_utc >= bts.i64()
 }
+
+fn test_at_os() {
+	println('Current OS is ${@OS}')
+	assert @OS in ['termux', 'android', 'wasm32_emscripten', 'linux', 'ios', 'macos', 'windows',
+		'freebsd', 'openbsd', 'netbsd', 'dragonfly', 'serenity', 'plan9', 'vinix', 'solaris', 'haiku',
+		'js_node', 'js_freestanding', 'js_browser']
+}
+
+fn test_at_ccompiler() {
+	println('Current C Compiler is ${@CCOMPILER}')
+	assert @CCOMPILER in ['gcc', 'tinyc', 'clang', 'emcc', 'mingw', 'msvc', 'cplusplus']
+}
+
+fn test_at_backend() {
+	println('Current language backend is ${@BACKEND}')
+	assert @BACKEND in ['c', 'golang', 'interpret', 'js_node', 'js_browser', 'js_freestanding',
+		'native', 'wasm']
+}
+
+fn test_at_platform() {
+	println('Current Platform is ${@PLATFORM}')
+	assert @PLATFORM in ['amd64', 'arm64', 'arm32', 'rv64', 'rv32', 'i386', 's390x', 'ppc64le',
+		'loongarch64', 'js_node', 'js_browser', 'js_freestanding', 'wasm32']
+}
diff --git a/vlib/v/tests/generics/generic_interface_field_test.v b/vlib/v/tests/generics/generic_interface_field_test.v
new file mode 100644
index 0000000000..752a6acb28
--- /dev/null
+++ b/vlib/v/tests/generics/generic_interface_field_test.v
@@ -0,0 +1,79 @@
+pub struct Range[T] {
+pub:
+	from      T
+	to        T
+	inclusive bool
+pub mut:
+	step T = T(1)
+	i    T
+mut:
+	started bool
+}
+
+pub fn (mut r Range[T]) next[T]() ?T {
+	if !r.started {
+		r.started = true
+		assert r.step > 0
+		if r.from > r.to {
+			r.step = -r.step
+		}
+		r.i = r.from
+	}
+	i := r.i
+	next_i := i + r.step
+	if r.inclusive {
+		if r.step < 0 && i < r.to {
+			return none
+		}
+		if r.step > 0 && i > r.to {
+			return none
+		}
+	} else {
+		if r.step < 0 && i <= r.to {
+			return none
+		}
+		if r.step > 0 && i >= r.to {
+			return none
+		}
+	}
+	r.i = next_i
+	return i
+}
+
+pub interface Iterator[T] {
+mut:
+	next() ?T
+}
+
+pub struct Zip[A, B] {
+mut:
+	a Iterator[A]
+	b Iterator[B]
+}
+
+pub struct Pair[A, B] {
+	a A
+	b B
+}
+
+pub fn (mut z Zip[A, B]) next[A, B]() ?Pair[A, B] {
+	a := z.a.next()?
+	b := z.b.next()?
+	return Pair[A, B]{a, b}
+}
+
+fn test_main() {
+	mut r1 := Range{
+		from: 5
+		to:   10
+	}
+	_ := Iterator[int](r1)
+
+	mut r2 := Range{
+		from: 10
+		to:   5
+	}
+	_ := Iterator[int](r2)
+
+	_ := Zip[int, int]{}
+}
diff --git a/vlib/v/tests/options/option_map_val_test.v b/vlib/v/tests/options/option_map_val_test.v
new file mode 100644
index 0000000000..fb045bba90
--- /dev/null
+++ b/vlib/v/tests/options/option_map_val_test.v
@@ -0,0 +1,6 @@
+fn test_main() {
+	mut m := map[int]?u32{}
+	if c := m[0] {
+		println('c:  ${c} not none!')
+	}
+}
diff --git a/vlib/v/tests/skip_unused/option_array_init.run.out b/vlib/v/tests/skip_unused/option_array_init.run.out
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/vlib/v/tests/skip_unused/option_array_init.skip_unused.run.out b/vlib/v/tests/skip_unused/option_array_init.skip_unused.run.out
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/vlib/v/tests/skip_unused/option_array_init.vv b/vlib/v/tests/skip_unused/option_array_init.vv
new file mode 100644
index 0000000000..d63fbd543a
--- /dev/null
+++ b/vlib/v/tests/skip_unused/option_array_init.vv
@@ -0,0 +1,6 @@
+fn main() {
+	mut a := []?u32{len: 0xFF}
+	if c := a[0] {
+		println('c:  ${c} not none!')
+	}
+}
diff --git a/vlib/v/token/token.v b/vlib/v/token/token.v
index 386d874cd6..f8fcad1c47 100644
--- a/vlib/v/token/token.v
+++ b/vlib/v/token/token.v
@@ -189,6 +189,10 @@ pub enum AtKind {
 	build_date
 	build_time
 	build_timestamp
+	os
+	ccompiler
+	backend
+	platform
 }
 
 pub const assign_tokens = [Kind.assign, .decl_assign, .plus_assign, .minus_assign, .mult_assign,
@@ -197,7 +201,8 @@ pub const assign_tokens = [Kind.assign, .decl_assign, .plus_assign, .minus_assig
 
 pub const valid_at_tokens = ['@VROOT', '@VMODROOT', '@VEXEROOT', '@FN', '@METHOD', '@MOD', '@STRUCT',
 	'@VEXE', '@FILE', '@DIR', '@LINE', '@COLUMN', '@VHASH', '@VCURRENTHASH', '@VMOD_FILE',
-	'@VMODHASH', '@FILE_LINE', '@LOCATION', '@BUILD_DATE', '@BUILD_TIME', '@BUILD_TIMESTAMP']
+	'@VMODHASH', '@FILE_LINE', '@LOCATION', '@BUILD_DATE', '@BUILD_TIME', '@BUILD_TIMESTAMP', '@OS',
+	'@CCOMPILER', '@BACKEND', '@PLATFORM']
 
 pub const token_str = build_token_str()