checker: fix compile-time call with string identifier expression (#8415)

vlib/v/ast/ast.v

@@ -1130,6 +1130,8 @@ pub struct ComptimeCall {
 pub:
 	has_parens  bool // if $() is used, for vfmt
 	method_name string
+	method_pos  token.Position
+	scope       &Scope
 	left        Expr
 	is_vweb     bool
 	vweb_tmpl   File
@@ -1137,7 +1139,8 @@ pub:
 	is_embed    bool
 	embed_file  EmbeddedFile
 pub mut:
-	sym table.TypeSymbol
+	sym         table.TypeSymbol
+	result_type table.Type
 }
 
 pub struct None {

vlib/v/checker/checker.v

@@ -3677,14 +3677,39 @@ fn (mut c Checker) comptime_call(mut node ast.ComptimeCall) table.Type {
 		c.nr_errors += c2.nr_errors
 	}
 	if node.method_name == 'html' {
-		return c.table.find_type_idx('vweb.Result')
+		rtyp := c.table.find_type_idx('vweb.Result')
+		node.result_type = rtyp
+		return rtyp
 	}
-	mut var := c.fn_scope.objects[node.method_name]
+	if node.is_vweb || node.method_name == 'method' {
-	if mut var is ast.Var {
+		return table.string_type
-		var.is_used = true
-		c.fn_scope.objects[node.method_name] = var
 	}
-	return table.string_type
+	// s.$my_str()
+	v := node.scope.find_var(node.method_name) or {
+		c.error('unknown identifier `$node.method_name`', node.method_pos)
+		return table.void_type
+	}
+	if v.typ != table.string_type {
+		s := c.expected_msg(v.typ, table.string_type)
+		c.error('invalid string method call: $s', node.method_pos)
+		return table.void_type
+	}
+	// note: we should use a compile-time evaluation function rather than handle here
+	// mut variables will not work after init
+	mut method_name := ''
+	if v.expr is ast.StringLiteral {
+		method_name = v.expr.val
+	} else {
+		c.add_error_detail(v.expr.type_name())
+		c.error('todo: not a string literal', node.method_pos)
+	}
+	f := node.sym.find_method(method_name) or {
+		c.error('could not find method `$method_name`', node.method_pos)
+		return table.void_type
+	}
+	println(f.name + ' ' + c.table.type_to_str(f.return_type))
+	node.result_type = f.return_type
+	return f.return_type
 }
 
 fn (mut c Checker) at_expr(mut node ast.AtExpr) table.Type {

vlib/v/checker/tests/comptime_call_no_unused_var.out

@@ -1 +1,29 @@
-
+print void
+vlib/v/checker/tests/comptime_call_no_unused_var.vv:11:8: error: unknown identifier `w`
+    9 |     abc := 'print'
+   10 |     test.$abc() // OK
+   11 |     test.$w()
+      |           ^
+   12 |     v := 4
+   13 |     test.$v()
+vlib/v/checker/tests/comptime_call_no_unused_var.vv:13:8: error: invalid string method call: expected `string`, not `int`
+   11 |     test.$w()
+   12 |     v := 4
+   13 |     test.$v()
+      |           ^
+   14 |     s := 'x' + 'y'
+   15 |     test.$s()
+vlib/v/checker/tests/comptime_call_no_unused_var.vv:15:8: error: todo: not a string literal
+   13 |     test.$v()
+   14 |     s := 'x' + 'y'
+   15 |     test.$s()
+      |           ^
+   16 |     s2 := 'x'
+   17 |     test.$s2()
+details: v.ast.InfixExpr
+vlib/v/checker/tests/comptime_call_no_unused_var.vv:17:8: error: could not find method `x`
+   15 |     test.$s()
+   16 |     s2 := 'x'
+   17 |     test.$s2()
+      |           ~~
+   18 | }

vlib/v/checker/tests/comptime_call_no_unused_var.vv

@@ -7,5 +7,12 @@ fn (test Test) print() {
 fn main() {
 	test := Test{}
 	abc := 'print'
-	test.$abc()
+	test.$abc() // OK
+	test.$w()
+	v := 4
+	test.$v()
+	s := 'x' + 'y'
+	test.$s()
+	s2 := 'x'
+	test.$s2()
 }

vlib/v/gen/comptime.v

@@ -57,9 +57,7 @@ fn (mut g Gen) comptime_call(node ast.ComptimeCall) {
 		}
 		return
 	}
-	g.writeln('// $' + 'method call. sym="$node.sym.name"')
+	g.writeln('// \$method call. sym="$node.sym.name"')
-	mut j := 0
-	result_type := g.table.find_type_idx('vweb.Result') // TODO not just vweb
 	if node.method_name == 'method' {
 		// `app.$method()`
 		m := node.sym.find_method(g.comp_for_method) or { return }
@@ -95,9 +93,10 @@ fn (mut g Gen) comptime_call(node ast.ComptimeCall) {
 		g.write(' ); // vweb action call with args')
 		return
 	}
+	mut j := 0
 	for method in node.sym.methods {
 		// if method.return_type != table.void_type {
-		if method.return_type != result_type {
+		if method.return_type != node.result_type {
 			continue
 		}
 		if method.params.len != 1 {
@@ -108,10 +107,12 @@ fn (mut g Gen) comptime_call(node ast.ComptimeCall) {
 		// p.error('`$p.expr_var.name` needs to be a reference')
 		// }
 		amp := '' // if receiver.is_mut && !p.expr_var.ptr { '&' } else { '' }
-		if j > 0 {
+		if node.is_vweb {
-			g.write(' else ')
+			if j > 0 {
+				g.write(' else ')
+			}
+			g.write('if (string_eq($node.method_name, _SLIT("$method.name"))) ')
 		}
-		g.write('if (string_eq($node.method_name, _SLIT("$method.name"))) ')
 		g.write('${util.no_dots(node.sym.name)}_${method.name}($amp ')
 		g.expr(node.left)
 		g.writeln(');')

vlib/v/gen/embed.v

@@ -27,7 +27,7 @@ fn (mut g Gen) gen_embed_file_init(node ast.ComptimeCall) {
 	g.writeln('\t\t.free_compressed = 0,')
 	g.writeln('\t\t.free_uncompressed = 0,')
 	g.writeln('\t\t.len = $file_size')
-	g.writeln('} // $' + 'embed_file("$node.embed_file.apath")')
+	g.writeln('} // \$embed_file("$node.embed_file.apath")')
 }
 
 // gen_embedded_data embeds data into the V target executable.

vlib/v/parser/comptime.v

@@ -43,20 +43,23 @@ fn (mut p Parser) hash() ast.HashStmt {
 }
 
 fn (mut p Parser) comp_call() ast.ComptimeCall {
+	err_node := ast.ComptimeCall{
+		scope: 0
+	}
 	p.check(.dollar)
 	error_msg := 'only `\$tmpl()`, `\$embed_file()` and `\$vweb.html()` comptime functions are supported right now'
 	if p.peek_tok.kind == .dot {
 		n := p.check_name() // skip `vweb.html()` TODO
 		if n != 'vweb' {
 			p.error(error_msg)
-			return ast.ComptimeCall{}
+			return err_node
 		}
 		p.check(.dot)
 	}
 	n := p.check_name() // (.name)
 	if n !in parser.supported_comptime_calls {
 		p.error(error_msg)
-		return ast.ComptimeCall{}
+		return err_node
 	}
 	is_embed_file := n == 'embed_file'
 	is_html := n == 'html'
@@ -74,7 +77,7 @@ fn (mut p Parser) comp_call() ast.ComptimeCall {
 		if epath == '' {
 			p.error_with_pos('please supply a valid relative or absolute file path to the file to embed',
 				spos)
-			return ast.ComptimeCall{}
+			return err_node
 		}
 		if !p.pref.is_fmt {
 			abs_path := os.real_path(epath)
@@ -85,12 +88,12 @@ fn (mut p Parser) comp_call() ast.ComptimeCall {
 				if !os.exists(epath) {
 					p.error_with_pos('"$epath" does not exist so it cannot be embedded',
 						spos)
-					return ast.ComptimeCall{}
+					return err_node
 				}
 				if !os.is_file(epath) {
 					p.error_with_pos('"$epath" is not a file so it cannot be embedded',
 						spos)
-					return ast.ComptimeCall{}
+					return err_node
 				}
 			} else {
 				epath = abs_path
@@ -98,6 +101,7 @@ fn (mut p Parser) comp_call() ast.ComptimeCall {
 		}
 		p.register_auto_import('v.embed_file')
 		return ast.ComptimeCall{
+			scope: 0
 			is_embed: true
 			embed_file: ast.EmbeddedFile{
 				rpath: s
@@ -126,11 +130,10 @@ fn (mut p Parser) comp_call() ast.ComptimeCall {
 		if !os.exists(path) {
 			if is_html {
 				p.error('vweb HTML template "$path" not found')
-				return ast.ComptimeCall{}
 			} else {
 				p.error('template file "$path" not found')
-				return ast.ComptimeCall{}
 			}
+			return err_node
 		}
 		// println('path is now "$path"')
 	}
@@ -185,6 +188,7 @@ fn (mut p Parser) comp_call() ast.ComptimeCall {
 		}
 	}
 	return ast.ComptimeCall{
+		scope: 0
 		is_vweb: true
 		vweb_tmpl: file
 		method_name: n
@@ -257,7 +261,9 @@ fn (mut p Parser) at() ast.AtExpr {
 fn (mut p Parser) comptime_selector(left ast.Expr) ast.Expr {
 	p.check(.dollar)
 	if p.peek_tok.kind == .lpar {
+		method_pos := p.tok.position()
 		method_name := p.check_name()
+		p.mark_var_as_used(method_name)
 		// `app.$action()` (`action` is a string)
 		p.check(.lpar)
 		mut args_var := ''
@@ -273,6 +279,8 @@ fn (mut p Parser) comptime_selector(left ast.Expr) ast.Expr {
 		return ast.ComptimeCall{
 			left: left
 			method_name: method_name
+			method_pos: method_pos
+			scope: p.scope
 			args_var: args_var
 		}
 	}

vlib/v/tests/comptime_call_test.v

@@ -0,0 +1,26 @@
+struct Test {}
+
+fn (test Test) v() {
+	println('in v()')
+}
+fn (test Test) i() int {
+	return 4
+}
+fn (test Test) s() string {
+	return 'test'
+}
+fn (test Test) s2() string {
+	return 'Two'
+}
+
+fn test_call() {
+	test := Test{}
+	sv := 'v'
+	test.$sv()
+	si := 'i'
+	ri := test.$si()
+	assert ri == 4
+	ss := 's'
+	rs := test.$ss()
+	assert rs == 'test'
+}