v: support @DIR (as a comptime equivalent to os.dir(@FILE)) at runtime) (#24742)

doc/docs.md

@@ -6052,6 +6052,7 @@ that are substituted at compile time:
 - `@MOD` => replaced with the name of the current V module.
 - `@STRUCT` => replaced with the name of the current V struct.
 - `@FILE` => replaced with the absolute path of the V source file.
+- `@DIR` => replaced with the absolute path of the *folder*, where the V source file is.
 - `@LINE` => replaced with the V line number where it appears (as a string).
 - `@FILE_LINE` => like `@FILE:@LINE`, but the file part is a relative path.
 - `@LOCATION` => file, line and name of the current type + method; suitable for logging.

vlib/v/checker/checker.v

@@ -2636,6 +2636,13 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 		'include', 'insert', 'preinclude', 'postinclude' {
 			original_flag := node.main
 			mut flag := node.main
+			if flag.contains('@DIR') {
+				vdir := c.dir_path()
+				val := flag.replace('@DIR', vdir)
+				node.val = '${node.kind} ${val}'
+				node.main = val
+				flag = val
+			}
 			if flag.contains('@VROOT') {
 				// c.note(checker.vroot_is_deprecated_message, node.pos)
 				vroot := util.resolve_vmodroot(flag.replace('@VROOT', '@VMODROOT'), c.file.path) or {
@@ -2742,6 +2749,10 @@ fn (mut c Checker) hash_stmt(mut node ast.HashStmt) {
 					return
 				}
 			}
+			if flag.contains('@DIR') {
+				// expand `@DIR` to its absolute path
+				flag = flag.replace('@DIR', c.dir_path())
+			}
 			if flag.contains('@VEXEROOT') {
 				// expand `@VEXEROOT` to its absolute path
 				flag = flag.replace('@VEXEROOT', c.pref.vroot)
@@ -3914,6 +3925,9 @@ fn (mut c Checker) at_expr(mut node ast.AtExpr) ast.Type {
 		.file_path {
 			node.val = os.real_path(c.file.path)
 		}
+		.file_dir {
+			node.val = os.real_path(os.dir(c.file.path))
+		}
 		.line_nr {
 			node.val = (node.pos.line_nr + 1).str()
 		}
@@ -5733,3 +5747,7 @@ pub fn (mut c Checker) update_unresolved_fixed_sizes() {
 		}
 	}
 }
+
+fn (mut c Checker) dir_path() string {
+	return os.real_path(os.dir(c.file.path))
+}

vlib/v/parser/comptime.v

@@ -466,6 +466,7 @@ fn (mut p Parser) at() ast.AtExpr {
 		'@MOD' { token.AtKind.mod_name }
 		'@STRUCT' { token.AtKind.struct_name }
 		'@FILE' { token.AtKind.file_path }
+		'@DIR' { token.AtKind.file_dir }
 		'@LINE' { token.AtKind.line_nr }
 		'@FILE_LINE' { token.AtKind.file_path_line_nr }
 		'@LOCATION' { token.AtKind.location }

vlib/v/scanner/tests/unknown_comptime_var_err.out

@@ -4,5 +4,5 @@ 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, @LINE, @COLUMN, @VHASH, @VCURRENTHASH, @VMOD_FILE, @VMODHASH,
+@STRUCT, @VEXE, @FILE, @DIR, @LINE, @COLUMN, @VHASH, @VCURRENTHASH, @VMOD_FILE, @VMODHASH,
 @FILE_LINE, @LOCATION, @BUILD_DATE, @BUILD_TIME, @BUILD_TIMESTAMP

vlib/v/tests/comptime/comptime_at_test.v

@@ -83,6 +83,16 @@ fn test_at_file() {
 	assert f == 'comptime_at_test.v'
 }
 
+fn test_at_dir() {
+	// Test @DIR
+	f := os.file_name(@DIR)
+	assert f == 'comptime'
+	assert os.dir(@FILE) == @DIR
+	d := @DIR
+	assert d.len > 0
+	assert !d.ends_with('.v')
+}
+
 fn test_at_file_len() {
 	// Test @FILE_LINE
 	line1, line2 := '${@LINE}', '${@FILE_LINE}'

vlib/v/tests/project_with_c_code/main.v

@@ -2,8 +2,15 @@ module main
 
 import v.tests.project_with_c_code.mod1
 
+#include "@DIR/relative.h"
+
+fn C.abc() int
+
 fn main() {
 	res := mod1.vadd(1, 2)
 	println(res)
 	assert res == 1003
+	res2 := C.abc()
+	assert res2 == 142
+	dump(res2)
 }

vlib/v/tests/project_with_c_code/main1_test.v

@@ -2,6 +2,11 @@
 // vtest retry: 3
 import v.tests.project_with_c_code.mod1
 
+#include "@DIR/relative.h"
+
+fn C.abc() int
+
 fn test_using_c_code_in_the_same_module_works() {
 	assert 1003 == mod1.vadd(1, 2)
+	assert 142 == C.abc()
 }

vlib/v/tests/project_with_c_code/relative.h

@@ -0,0 +1,5 @@
+int abc() {
+   return 142;
+}
+
+	 

vlib/v/token/token.v

@@ -174,6 +174,7 @@ pub enum AtKind {
 	struct_name
 	vexe_path
 	file_path
+	file_dir
 	line_nr
 	column_nr
 	vhash
@@ -195,8 +196,8 @@ pub const assign_tokens = [Kind.assign, .decl_assign, .plus_assign, .minus_assig
 	.left_shift_assign, .unsigned_right_shift_assign, .boolean_and_assign, .boolean_or_assign]
 
 pub const valid_at_tokens = ['@VROOT', '@VMODROOT', '@VEXEROOT', '@FN', '@METHOD', '@MOD', '@STRUCT',
-	'@VEXE', '@FILE', '@LINE', '@COLUMN', '@VHASH', '@VCURRENTHASH', '@VMOD_FILE', '@VMODHASH',
-	'@FILE_LINE', '@LOCATION', '@BUILD_DATE', '@BUILD_TIME', '@BUILD_TIMESTAMP']
+	'@VEXE', '@FILE', '@DIR', '@LINE', '@COLUMN', '@VHASH', '@VCURRENTHASH', '@VMOD_FILE',
+	'@VMODHASH', '@FILE_LINE', '@LOCATION', '@BUILD_DATE', '@BUILD_TIME', '@BUILD_TIMESTAMP']
 
 pub const token_str = build_token_str()