From eb6cbeb28b808e833cf03da9061b086918cb18d7 Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Sun, 21 Jul 2024 07:45:57 -0300
Subject: [PATCH] checker,cgen: fix typeof(var.typ) with comptime $for
 variables (#21901)

---
 vlib/v/checker/tests/typeof_comptime_test.out | 14 +++++++++
 vlib/v/checker/tests/typeof_comptime_test.vv  | 30 +++++++++++++++++++
 vlib/v/comptime/comptimeinfo.v                | 26 +++++++++-------
 vlib/v/gen/c/cgen.v                           |  1 +
 vlib/v/gen/c/comptime.v                       |  3 ++
 5 files changed, 63 insertions(+), 11 deletions(-)
 create mode 100644 vlib/v/checker/tests/typeof_comptime_test.out
 create mode 100644 vlib/v/checker/tests/typeof_comptime_test.vv

diff --git a/vlib/v/checker/tests/typeof_comptime_test.out b/vlib/v/checker/tests/typeof_comptime_test.out
new file mode 100644
index 000000000..dade3d333
--- /dev/null
+++ b/vlib/v/checker/tests/typeof_comptime_test.out
@@ -0,0 +1,14 @@
+field> 8 int
+variant> 8 int
+SumType(123)
+field> 8 int
+field> 21 string
+variant> 8 int
+variant> 21 string
+SumType('foo')
+field> 8 int
+variant> 8 int
+field> 8 int
+field> 21 string
+variant> 8 int
+variant> 21 string
diff --git a/vlib/v/checker/tests/typeof_comptime_test.vv b/vlib/v/checker/tests/typeof_comptime_test.vv
new file mode 100644
index 000000000..082f08a3d
--- /dev/null
+++ b/vlib/v/checker/tests/typeof_comptime_test.vv
@@ -0,0 +1,30 @@
+type SumType = int | string
+
+struct Test {
+	a int
+	b string
+}
+
+fn get_as_sumtype[T, R](struct_ T, name string, typname string) R {
+	$for f2 in T.fields {
+		println('field> ${f2.typ} ${typeof(f2.typ).name}')
+		if f2.name == name {
+			val := struct_.$(f2.name)
+			$for f in R.variants {
+				println('variant> ${f.typ} ${typeof(f.typ).name}')
+				if typeof(f.typ).name == typname {
+					return R(val)
+				}
+			}
+		}
+	}
+	return R{}
+}
+
+fn test_main() {
+	println(get_as_sumtype[Test, SumType](Test{ a: 123 }, 'a', 'int'))
+	println(get_as_sumtype[Test, SumType](Test{ b: 'foo' }, 'b', 'string'))
+
+	assert get_as_sumtype[Test, SumType](Test{ a: 123 }, 'a', 'int') == SumType(123)
+	assert get_as_sumtype[Test, SumType](Test{ b: 'foo' }, 'b', 'string') == SumType('foo')
+}
diff --git a/vlib/v/comptime/comptimeinfo.v b/vlib/v/comptime/comptimeinfo.v
index 86388a513..bc1edf3e6 100644
--- a/vlib/v/comptime/comptimeinfo.v
+++ b/vlib/v/comptime/comptimeinfo.v
@@ -93,17 +93,7 @@ pub fn (mut ct ComptimeInfo) get_comptime_var_type(node ast.Expr) ast.Type {
 		// val.$(field.name)
 		return ct.get_comptime_selector_type(node, ast.void_type)
 	} else if node is ast.SelectorExpr && ct.is_comptime_selector_type(node) {
-		if node.expr is ast.Ident {
-			match node.expr.name {
-				ct.comptime_for_variant_var {
-					return ct.type_map['${ct.comptime_for_variant_var}.typ']
-				}
-				else {
-					// field_var.typ from $for field
-					return ct.comptime_for_field_type
-				}
-			}
-		}
+		return ct.get_type_from_comptime_var(node.expr as ast.Ident)
 	} else if node is ast.ComptimeCall {
 		method_name := ct.comptime_for_method
 		left_sym := ct.table.sym(ct.resolver.unwrap_generic(node.left_type))
@@ -117,6 +107,20 @@ pub fn (mut ct ComptimeInfo) get_comptime_var_type(node ast.Expr) ast.Type {
 	return ast.void_type
 }
 
+// get_type_from_comptime_var retrives the comptime type related to $for variable
+@[inline]
+pub fn (mut ct ComptimeInfo) get_type_from_comptime_var(var ast.Ident) ast.Type {
+	return match var.name {
+		ct.comptime_for_variant_var {
+			ct.type_map['${ct.comptime_for_variant_var}.typ']
+		}
+		else {
+			// field_var.typ from $for field
+			ct.comptime_for_field_type
+		}
+	}
+}
+
 pub fn (mut ct ComptimeInfo) get_comptime_selector_var_type(node ast.ComptimeSelector) (ast.StructField, string) {
 	field_name := ct.comptime_for_field_value.name
 	left_sym := ct.table.sym(ct.resolver.unwrap_generic(node.left_type))
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index 2ed076824..b4255d23e 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -324,6 +324,7 @@ pub fn gen(files []&ast.File, mut table ast.Table, pref_ &pref.Preferences) (str
 		inner_loop: unsafe { &ast.empty_stmt }
 		field_data_type: ast.Type(table.find_type_idx('FieldData'))
 		enum_data_type: ast.Type(table.find_type_idx('EnumData'))
+		variant_data_type: ast.Type(table.find_type_idx('VariantData'))
 		is_cc_msvc: pref_.ccompiler == 'msvc'
 		use_segfault_handler: !('no_segfault_handler' in pref_.compile_defines
 			|| pref_.os in [.wasm32, .wasm32_emscripten])
diff --git a/vlib/v/gen/c/comptime.v b/vlib/v/gen/c/comptime.v
index ed222ecaf..23b4a1a91 100644
--- a/vlib/v/gen/c/comptime.v
+++ b/vlib/v/gen/c/comptime.v
@@ -767,6 +767,9 @@ fn (mut g Gen) resolve_comptime_type(node ast.Expr, default_type ast.Type) ast.T
 	if (node is ast.Ident && g.comptime.is_comptime_var(node)) || node is ast.ComptimeSelector {
 		return g.comptime.get_comptime_var_type(node)
 	} else if node is ast.SelectorExpr && node.expr_type != 0 {
+		if node.expr is ast.Ident && g.comptime.is_comptime_selector_type(node) {
+			return g.comptime.get_type_from_comptime_var(node.expr)
+		}
 		sym := g.table.sym(g.unwrap_generic(node.expr_type))
 		if f := g.table.find_field_with_embeds(sym, node.field_name) {
 			return f.typ
-- 
2.39.5