Commit 65016dff32

@@ -50,6 +50,47 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         "tmp.zig:2:20: error: TypeInfo.Enum.tag_type must be an integer type, not 'bool'",
     });
 
+    cases.add("extern struct with extern-compatible but inferred integer tag type",
+        \\pub const E = enum {
+        \\@"0",@"1",@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12",
+        \\@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"20",@"21",@"22",@"23",
+        \\@"24",@"25",@"26",@"27",@"28",@"29",@"30",@"31",@"32",@"33",@"34",
+        \\@"35",@"36",@"37",@"38",@"39",@"40",@"41",@"42",@"43",@"44",@"45",
+        \\@"46",@"47",@"48",@"49",@"50",@"51",@"52",@"53",@"54",@"55",@"56",
+        \\@"57",@"58",@"59",@"60",@"61",@"62",@"63",@"64",@"65",@"66",@"67",
+        \\@"68",@"69",@"70",@"71",@"72",@"73",@"74",@"75",@"76",@"77",@"78",
+        \\@"79",@"80",@"81",@"82",@"83",@"84",@"85",@"86",@"87",@"88",@"89",
+        \\@"90",@"91",@"92",@"93",@"94",@"95",@"96",@"97",@"98",@"99",@"100",
+        \\@"101",@"102",@"103",@"104",@"105",@"106",@"107",@"108",@"109",
+        \\@"110",@"111",@"112",@"113",@"114",@"115",@"116",@"117",@"118",
+        \\@"119",@"120",@"121",@"122",@"123",@"124",@"125",@"126",@"127",
+        \\@"128",@"129",@"130",@"131",@"132",@"133",@"134",@"135",@"136",
+        \\@"137",@"138",@"139",@"140",@"141",@"142",@"143",@"144",@"145",
+        \\@"146",@"147",@"148",@"149",@"150",@"151",@"152",@"153",@"154",
+        \\@"155",@"156",@"157",@"158",@"159",@"160",@"161",@"162",@"163",
+        \\@"164",@"165",@"166",@"167",@"168",@"169",@"170",@"171",@"172",
+        \\@"173",@"174",@"175",@"176",@"177",@"178",@"179",@"180",@"181",
+        \\@"182",@"183",@"184",@"185",@"186",@"187",@"188",@"189",@"190",
+        \\@"191",@"192",@"193",@"194",@"195",@"196",@"197",@"198",@"199",
+        \\@"200",@"201",@"202",@"203",@"204",@"205",@"206",@"207",@"208",
+        \\@"209",@"210",@"211",@"212",@"213",@"214",@"215",@"216",@"217",
+        \\@"218",@"219",@"220",@"221",@"222",@"223",@"224",@"225",@"226",
+        \\@"227",@"228",@"229",@"230",@"231",@"232",@"233",@"234",@"235",
+        \\@"236",@"237",@"238",@"239",@"240",@"241",@"242",@"243",@"244",
+        \\@"245",@"246",@"247",@"248",@"249",@"250",@"251",@"252",@"253",
+        \\@"254",@"255"
+        \\};
+        \\pub const S = extern struct {
+        \\    e: E,
+        \\};
+        \\export fn entry() void {
+        \\    if (@TagType(E) != u8) @compileError("did not infer u8 tag type");
+        \\    const s: S = undefined;
+        \\}
+    , &[_][]const u8{
+        "tmp.zig:31:5: error: extern structs cannot contain fields of type 'E'",
+    });
+
     cases.add("@Type for tagged union with extra enum field",
         \\const TypeInfo = @import("builtin").TypeInfo;
         \\const Tag = @Type(.{