allow integer and float literals to be passed to var params

closes #623

src/ir.cpp

@@ -11804,7 +11804,8 @@ static bool ir_analyze_fn_call_generic_arg(IrAnalyze *ira, AstNode *fn_proto_nod
         }
     }
 
-    bool comptime_arg = param_decl_node->data.param_decl.is_inline;
+    bool comptime_arg = param_decl_node->data.param_decl.is_inline ||
+        casted_arg->value.type->id == TypeTableEntryIdNumLitInt || casted_arg->value.type->id == TypeTableEntryIdNumLitFloat;
 
     ConstExprValue *arg_val;
 
@@ -11829,6 +11830,12 @@ static bool ir_analyze_fn_call_generic_arg(IrAnalyze *ira, AstNode *fn_proto_nod
         var->shadowable = !comptime_arg;
 
         *next_proto_i += 1;
+    } else if (casted_arg->value.type->id == TypeTableEntryIdNumLitInt ||
+            casted_arg->value.type->id == TypeTableEntryIdNumLitFloat)
+    {
+        ir_add_error(ira, casted_arg,
+            buf_sprintf("compiler bug: integer and float literals in var args function must be casted. https://github.com/zig-lang/zig/issues/557"));
+        return false;
     }
 
     if (!comptime_arg) {

test/cases/fn.zig

@@ -94,3 +94,13 @@ test "inline function call" {
 }
 
 fn add(a: i32, b: i32) i32 { return a + b; }
+
+
+test "number literal as an argument" {
+    numberLiteralArg(3);
+    comptime numberLiteralArg(3);
+}
+
+fn numberLiteralArg(a: var) void {
+    assert(a == 3);
+}

test/compile_errors.zig

@@ -1723,7 +1723,7 @@ pub fn addCases(cases: &tests.CompileErrorContext) void {
         \\}
         \\
         \\export fn entry() usize { return @sizeOf(@typeOf(bar)); }
-    , ".tmp_source.zig:10:16: error: parameter of type '(integer literal)' requires comptime");
+    , ".tmp_source.zig:10:16: error: compiler bug: integer and float literals in var args function must be casted");
 
     cases.add("assign too big number to u16",
         \\export fn foo() void {