checker: error if cannot generic infer type from empty array ([])

vlang · Nov 17, 2024 · 1a2884c · 1a2884c
1 parent e6c6c24
commit 1a2884c
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diff --git a/vlib/v/checker/check_types.v b/vlib/v/checker/check_types.v
@@ -1044,6 +1044,10 @@ fn (mut c Checker) infer_fn_generic_types(func &ast.Fn, mut node ast.CallExpr) {
 							&& param_elem_sym.name !in c.table.cur_fn.generic_names {
 							arg_elem_typ, param_elem_typ = arg_elem_sym.info.elem_type, param_elem_sym.info.elem_type
 							arg_elem_sym, param_elem_sym = c.table.sym(arg_elem_typ), c.table.sym(param_elem_typ)
+						} else if arg.expr is ast.ArrayInit && arg.expr.exprs.len == 0 {
+							c.error('could not infer generic type `${gt_name}` in call to `${func.name}`',
+								node.pos)
+							return
 						} else {
 							if param_elem_sym.name == gt_name {
 								typ = arg_elem_typ

diff --git a/vlib/v/checker/tests/generic_fn_array_param_not_infer_type_err.out b/vlib/v/checker/tests/generic_fn_array_param_not_infer_type_err.out
@@ -0,0 +1,5 @@
+vlib/v/checker/tests/generic_fn_array_param_not_infer_type_err.vv:3:8: error: could not infer generic type `T` in call to `arrays.sum`
+    1 | import arrays
+    2 | 
+    3 | arrays.sum([]) or { panic(err) }
+      |        ~~~~~~~
diff --git a/vlib/v/checker/tests/generic_fn_array_param_not_infer_type_err.vv b/vlib/v/checker/tests/generic_fn_array_param_not_infer_type_err.vv
@@ -0,0 +1,3 @@
+import arrays
+
+arrays.sum([]) or { panic(err) }