comptime: fix embed file with variable argument (fix #16360) (#16375)

vlib/v/ast/ast.v

@@ -712,10 +712,10 @@ pub mut:
 [minify]
 pub struct EmbeddedFile {
 pub:
-	rpath            string // used in the source code, as an ID/key to the embed
-	apath            string // absolute path during compilation to the resource
 	compression_type string
 pub mut:
+	rpath string // used in the source code, as an ID/key to the embed
+	apath string // absolute path during compilation to the resource
 	// these are set by gen_embed_file_init in v/gen/c/embed
 	is_compressed bool
 	bytes         []u8
@@ -1683,7 +1683,6 @@ pub:
 	method_pos  token.Pos
 	scope       &Scope = unsafe { nil }
 	left        Expr
-	args_var    string
 	//
 	is_vweb   bool
 	vweb_tmpl File
@@ -1698,6 +1697,7 @@ pub mut:
 	left_type   Type
 	result_type Type
 	env_value   string
+	args_var    string
 	args        []CallArg
 	embed_file  EmbeddedFile
 }

vlib/v/checker/comptime.v

@@ -2,6 +2,7 @@
 // Use of this source code is governed by an MIT license that can be found in the LICENSE file.
 module checker
 
+import os
 import v.ast
 import v.pref
 import v.token
@@ -29,6 +30,46 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) ast.Type {
 		return ast.string_type
 	}
 	if node.is_embed {
+		if node.args.len == 1 {
+			embed_arg := node.args[0]
+			mut raw_path := ''
+			if embed_arg.expr is ast.StringLiteral {
+				raw_path = embed_arg.expr.val
+			} else if embed_arg.expr is ast.Ident {
+				if var := c.fn_scope.find_var(embed_arg.expr.name) {
+					if var.expr is ast.StringLiteral {
+						raw_path = var.expr.val
+					}
+				}
+			}
+			mut escaped_path := raw_path.replace('/', os.path_separator)
+			// Validate that the epath exists, and that it is actually a file.
+			if escaped_path == '' {
+				c.error('supply a valid relative or absolute file path to the file to embed, that is known at compile time',
+					node.pos)
+				return ast.string_type
+			}
+			abs_path := os.real_path(escaped_path)
+			// check absolute path first
+			if !os.exists(abs_path) {
+				// ... look relative to the source file:
+				escaped_path = os.real_path(os.join_path_single(os.dir(c.file.path), escaped_path))
+				if !os.exists(escaped_path) {
+					c.error('"$escaped_path" does not exist so it cannot be embedded',
+						node.pos)
+					return ast.string_type
+				}
+				if !os.is_file(escaped_path) {
+					c.error('"$escaped_path" is not a file so it cannot be embedded',
+						node.pos)
+					return ast.string_type
+				}
+			} else {
+				escaped_path = abs_path
+			}
+			node.embed_file.rpath = raw_path
+			node.embed_file.apath = escaped_path
+		}
 		// c.file.embedded_files << node.embed_file
 		if node.embed_file.compression_type !in constants.valid_comptime_compression_types {
 			supported := constants.valid_comptime_compression_types.map('.$it').join(', ')

vlib/v/embed_file/tests/embed_file_with_variable_arg_test.v

@@ -0,0 +1,6 @@
+fn test_embed_file_with_variable_arg() {
+	path := './a.txt'
+	s := $embed_file(path).to_string()
+	println(s)
+	assert s.trim_space() == 'test'
+}

vlib/v/fmt/fmt.v

@@ -1882,9 +1882,9 @@ pub fn (mut f Fmt) comptime_call(node ast.ComptimeCall) {
 	} else {
 		if node.is_embed {
 			if node.embed_file.compression_type == 'none' {
-				f.write("\$embed_file('$node.embed_file.rpath')")
+				f.write('\$embed_file(${node.args[0].expr})')
 			} else {
-				f.write("\$embed_file('$node.embed_file.rpath', .$node.embed_file.compression_type)")
+				f.write('\$embed_file(${node.args[0].expr}, .$node.embed_file.compression_type)')
 			}
 		} else if node.is_env {
 			f.write("\$env('$node.args_var')")

vlib/v/parser/comptime.v

@@ -123,8 +123,12 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	}
 	literal_string_param := if is_html { '' } else { p.tok.lit }
 	path_of_literal_string_param := literal_string_param.replace('/', os.path_separator)
+	mut arg := ast.CallArg{}
 	if !is_html {
-		p.check(.string)
+		arg_expr := p.expr(0)
+		arg = ast.CallArg{
+			expr: arg_expr
+		}
 	}
 	mut embed_compression_type := 'none'
 	if is_embed_file {
@@ -137,33 +141,6 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 	p.check(.rpar)
 	// $embed_file('/path/to/file')
 	if is_embed_file {
-		mut epath := path_of_literal_string_param
-		// Validate that the epath exists, and that it is actually a file.
-		if epath == '' {
-			p.error_with_pos('supply a valid relative or absolute file path to the file to embed',
-				start_pos)
-			return err_node
-		}
-		if !p.pref.is_fmt {
-			abs_path := os.real_path(epath)
-			// check absolute path first
-			if !os.exists(abs_path) {
-				// ... look relative to the source file:
-				epath = os.real_path(os.join_path_single(os.dir(p.file_name), epath))
-				if !os.exists(epath) {
-					p.error_with_pos('"$epath" does not exist so it cannot be embedded',
-						start_pos)
-					return err_node
-				}
-				if !os.is_file(epath) {
-					p.error_with_pos('"$epath" is not a file so it cannot be embedded',
-						start_pos)
-					return err_node
-				}
-			} else {
-				epath = abs_path
-			}
-		}
 		p.register_auto_import('v.preludes.embed_file')
 		if embed_compression_type == 'zlib' {
 			p.register_auto_import('v.preludes.embed_file.zlib')
@@ -172,10 +149,9 @@ fn (mut p Parser) comptime_call() ast.ComptimeCall {
 			scope: 0
 			is_embed: true
 			embed_file: ast.EmbeddedFile{
-				rpath: literal_string_param
-				apath: epath
 				compression_type: embed_compression_type
 			}
+			args: [arg]
 			pos: start_pos.extend(p.prev_tok.pos())
 		}
 	}