v.eval: lookup constants in builtin, when they are not found in the…

… current module; add test (#23745)

vlib/v/eval/eval.v

@@ -86,7 +86,11 @@ pub fn (mut e Eval) eval(mut files []&ast.File) {
 
 // first arg is receiver (if method)
 pub fn (mut e Eval) run_func(func ast.FnDecl, _args ...Object) {
-	e.back_trace << EvalTrace{func.idx, func.source_file.idx, func.pos.line_nr}
+	e.back_trace << EvalTrace{func.idx, if unsafe { func.source_file != 0 } {
+		func.source_file.idx
+	} else {
+		0
+	}, func.pos.line_nr}
 	old_mod := e.cur_mod
 	old_file := e.cur_file
 	e.cur_mod = func.mod

vlib/v/eval/expr.c.v

@@ -222,11 +222,18 @@ pub fn (mut e Eval) expr(expr ast.Expr, expecting ast.Type) Object {
 					return e.local_vars[expr.name].val
 				}
 				.constant {
+					key := expr.name.all_after_last('.')
 					return if expr.name.contains('.') {
 						e.mods[expr.name.all_before_last('.')]
 					} else {
 						e.mods[e.cur_mod]
-					}[expr.name.all_after_last('.')] or { ast.EmptyStmt{} } as Object
+					}[key] or {
+						if builtin_constant := e.mods['builtin'][key] {
+							builtin_constant
+						} else {
+							e.error('unknown constant `${key}`')
+						}
+					} as Object
 				}
 				else {
 					e.error('unknown ident kind for `${expr.name}`: ${expr.kind}')

vlib/v/eval/testdata/constants_and_casts.out

@@ -0,0 +1,4 @@
+-2147483648
+2147483647
+2147483647
+-2147483648

vlib/v/eval/testdata/constants_and_casts.vv

@@ -0,0 +1,11 @@
+const local_max_int = int(2147483647)
+const local_min_int = int(-2147483648)
+const i64_min_int32 = i64(local_min_int + 1) - 1
+const i64_max_int32 = i64(local_max_int - 1) + 1
+const abc = i64(max_int)
+const def = i64(min_int)
+
+println(i64_min_int32)
+println(i64_max_int32)
+println(abc)
+println(def)