checker: fix private symbol visibility checking

vlib/builtin/cfns.c.v

@@ -233,7 +233,7 @@ fn C.sysctl(name &int, namelen u32, oldp voidptr, oldlenp voidptr, newp voidptr,
 @[trusted]
 fn C._fileno(int) int
 
-type C.intptr_t = voidptr
+pub type C.intptr_t = voidptr
 
 fn C._get_osfhandle(fd int) C.intptr_t
 

vlib/builtin/int.v

@@ -7,7 +7,7 @@ pub struct VContext {
 	allocator int
 }
 
-type byte = u8
+pub type byte = u8
 
 // ptr_str returns the address of `ptr` as a `string`.
 pub fn ptr_str(ptr voidptr) string {

vlib/builtin/js/int.js.v

@@ -1,6 +1,6 @@
 module builtin
 
-type byte = u8
+pub type byte = u8
 
 pub const min_i8 = i8(-128)
 pub const max_i8 = i8(127)

vlib/builtin/wasm/wasi/int.v

@@ -1,6 +1,6 @@
 module builtin
 
-type byte = u8
+pub type byte = u8
 
 // type i32 = int
 

vlib/compress/szip/szip.c.v

@@ -14,7 +14,7 @@ pub:
 pub struct C.zip_t {
 }
 
-type Zip = C.zip_t
+pub type Zip = C.zip_t
 
 pub type Fn_on_extract_entry = fn (&&char, &&char) int
 

vlib/encoding/csv/csv_reader_random_access.v

@@ -421,7 +421,7 @@ pub fn (mut cr RandomAccessReader) get_cell(cfg GetCellConfig) !string {
 	return cr.default_cell
 }
 
-type CellValue = f32 | int | string
+pub type CellValue = f32 | int | string
 
 // get_cellt read a single cell and return a sum type CellValue
 pub fn (mut cr RandomAccessReader) get_cellt(cfg GetCellConfig) !CellValue {

vlib/v/checker/checker.v

@@ -5293,10 +5293,25 @@ fn (mut c Checker) ensure_type_exists(typ ast.Type, pos token.Pos) bool {
 		return false
 	}
 	sym := c.table.sym(typ)
-	if !c.is_builtin_mod && sym.kind == .struct && !sym.is_pub && sym.mod != c.mod {
-		c.error('struct `${sym.name}` was declared as private to module `${sym.mod}`, so it can not be used inside module `${c.mod}`',
-			pos)
-		return false
+	if !c.is_builtin_mod && sym.kind in [.struct, .alias, .sum_type, .function]! && !sym.is_pub
+		&& sym.mod != c.mod && sym.mod != 'main' {
+		if sym.kind == .function {
+			fn_info := sym.info as ast.FnType
+			// hack: recover fn mod from func name
+			mut fn_mod := fn_info.func.name.all_before_last('.')
+			if fn_mod == fn_info.func.name {
+				fn_mod = 'builtin'
+			}
+			if fn_mod != '' && fn_mod != c.mod && fn_info.func.name != '' && !fn_info.is_anon {
+				c.error('function type `${fn_info.func.name}` was declared as private to module `${fn_mod}`, so it can not be used inside module `${c.mod}`',
+					pos)
+				return false
+			}
+		} else {
+			c.error('${sym.kind} `${sym.name}` was declared as private to module `${sym.mod}`, so it can not be used inside module `${c.mod}`',
+				pos)
+			return false
+		}
 	}
 	match sym.kind {
 		.placeholder {

vlib/v/checker/tests/modules/private_symbol.out

@@ -0,0 +1,21 @@
+vlib/v/checker/tests/modules/private_symbol/main.v:10:11: error: function `priv_sym.priv` is private
+    8 | 
+    9 | fn main() {
+   10 |     priv_sym.priv()
+      |              ~~~~~~
+   11 |     a := priv_sym.Foo(0)
+   12 |     dump(a)
+vlib/v/checker/tests/modules/private_symbol/main.v:11:16: error: alias `priv_sym.Foo` was declared as private to module `priv_sym`, so it can not be used inside module `main`
+    9 | fn main() {
+   10 |     priv_sym.priv()
+   11 |     a := priv_sym.Foo(0)
+      |                   ~~~~~~
+   12 |     dump(a)
+   13 |     b := priv_sym.BarFn(t)
+vlib/v/checker/tests/modules/private_symbol/main.v:13:16: error: function type `priv_sym.BarFn` was declared as private to module `priv_sym`, so it can not be used inside module `main`
+   11 |     a := priv_sym.Foo(0)
+   12 |     dump(a)
+   13 |     b := priv_sym.BarFn(t)
+      |                   ~~~~~~~~
+   14 |     dump(b)
+   15 |     c := priv_sym.PubFoo(0)

vlib/v/checker/tests/modules/private_symbol/main.v

@@ -0,0 +1,19 @@
+module main
+
+import priv_sym
+
+fn t() int {
+	return 0
+}
+
+fn main() {
+	priv_sym.priv()
+	a := priv_sym.Foo(0)
+	dump(a)
+	b := priv_sym.BarFn(t)
+	dump(b)
+	c := priv_sym.PubFoo(0)
+	dump(c)
+	d := priv_sym.PubBarFn(t)
+	dump(d)
+}

vlib/v/checker/tests/modules/private_symbol/priv_sym.v

@@ -0,0 +1,12 @@
+// sub module
+module priv_sym
+
+type Foo = int
+pub type PubFoo = int
+
+type BarFn = fn () int
+
+pub type PubBarFn = fn () int
+
+fn priv() {
+}

vlib/x/templating/dtm/dynamic_template_manager.v

@@ -7,7 +7,7 @@ import time
 import regex
 
 // These are all the types of dynamic values that the DTM allows to be returned in the context of a map
-type DtmMultiTypeMap = f32 | f64 | i16 | i64 | i8 | int | string | u16 | u32 | u64 | u8
+pub type DtmMultiTypeMap = f32 | f64 | i16 | i64 | i8 | int | string | u16 | u32 | u64 | u8
 
 // type MiddlewareFn = fn (mut Context, string) bool