ability to set tag values of enums

also remove support for enums with 0 values

closes #305

2 files changed, 103 insertions, 8 deletions

diff --git a/test/cases/enum.zig b/test/cases/enum.zig
index 6df858a48f..eda3cf6376 100644
--- a/test/cases/enum.zig
+++ b/test/cases/enum.zig
@@ -137,7 +137,6 @@ const AlignTestEnum = enum {
     B: u64,
 };
 
-const ValueCount0 = enum {};
 const ValueCount1 = enum { I0 };
 const ValueCount2 = enum { I0, I1 };
 const ValueCount256 = enum {
@@ -183,7 +182,6 @@ const ValueCount257 = enum {
 
 test "enum sizes" {
     comptime {
-        assert(@sizeOf(ValueCount0) == 0);
         assert(@sizeOf(ValueCount1) == 0);
         assert(@sizeOf(ValueCount2) == 1);
         assert(@sizeOf(ValueCount256) == 1);
@@ -292,3 +290,57 @@ test "casting enum to its tag type" {
 fn testCastEnumToTagType(value: Small2) {
     assert(u2(value) == 1);
 }
+
+const MultipleChoice = enum(u32) {
+    A = 20,
+    B = 40,
+    C = 60,
+    D = 1000,
+};
+
+test "enum with specified tag values" {
+    testEnumWithSpecifiedTagValues(MultipleChoice.C);
+    comptime testEnumWithSpecifiedTagValues(MultipleChoice.C);
+}
+
+fn testEnumWithSpecifiedTagValues(x: MultipleChoice) {
+    assert(u32(x) == 60);
+    assert(1234 == switch (x) {
+        MultipleChoice.A => 1,
+        MultipleChoice.B => 2,
+        MultipleChoice.C => u32(1234),
+        MultipleChoice.D => 4,
+    });
+}
+
+const MultipleChoice2 = enum(u32) {
+    Unspecified1,
+    A = 20,
+    Unspecified2,
+    B = 40,
+    Unspecified3,
+    C = 60,
+    Unspecified4,
+    D = 1000,
+    Unspecified5,
+};
+
+test "enum with specified and unspecified tag values" {
+    testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
+    comptime testEnumWithSpecifiedAndUnspecifiedTagValues(MultipleChoice2.D);
+}
+
+fn testEnumWithSpecifiedAndUnspecifiedTagValues(x: MultipleChoice2) {
+    assert(u32(x) == 1000);
+    assert(1234 == switch (x) {
+        MultipleChoice2.A => 1,
+        MultipleChoice2.B => 2,
+        MultipleChoice2.C => 3,
+        MultipleChoice2.D => u32(1234),
+        MultipleChoice2.Unspecified1 => 5,
+        MultipleChoice2.Unspecified2 => 6,
+        MultipleChoice2.Unspecified3 => 7,
+        MultipleChoice2.Unspecified4 => 8,
+        MultipleChoice2.Unspecified5 => 9,
+    });
+}
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 367dec08b3..e1de167ac5 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -2307,11 +2307,11 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
 
     cases.add("@memberType enum out of bounds",
         \\comptime {
-        \\    _ = @memberType(Foo, 0);
+        \\    _ = @memberType(Foo, 1);
         \\}
-        \\const Foo = enum {};
+        \\const Foo = enum {A,};
     ,
-        ".tmp_source.zig:2:26: error: member index 0 out of bounds; 'Foo' has 0 members");
+        ".tmp_source.zig:2:26: error: member index 1 out of bounds; 'Foo' has 1 members");
 
     cases.add("@memberName on unsupported type",
         \\comptime {
@@ -2330,11 +2330,11 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
 
     cases.add("@memberName enum out of bounds",
         \\comptime {
-        \\    _ = @memberName(Foo, 0);
+        \\    _ = @memberName(Foo, 1);
         \\}
-        \\const Foo = enum {};
+        \\const Foo = enum {A,};
     ,
-        ".tmp_source.zig:2:26: error: member index 0 out of bounds; 'Foo' has 0 members");
+        ".tmp_source.zig:2:26: error: member index 1 out of bounds; 'Foo' has 1 members");
 
     cases.add("calling var args extern function, passing array instead of pointer",
         \\export fn entry() {
@@ -2447,4 +2447,47 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
         \\}
     ,
         ".tmp_source.zig:1:19: error: expected unsigned integer, found 'i2'");
+
+    cases.add("struct fields with value assignments",
+        \\const MultipleChoice = struct {
+        \\    A: i32 = 20,
+        \\};
+        \\export fn entry() {
+        \\        var x: MultipleChoice = undefined;
+        \\}
+    ,
+        ".tmp_source.zig:2:14: error: enums, not structs, support field assignment");
+
+    cases.add("union fields with value assignments",
+        \\const MultipleChoice = union {
+        \\    A: i32 = 20,
+        \\};
+        \\export fn entry() {
+        \\        var x: MultipleChoice = undefined;
+        \\}
+    ,
+        ".tmp_source.zig:2:14: error: enums, not unions, support field assignment");
+
+    cases.add("enum with 0 fields",
+        \\const Foo = enum {};
+        \\export fn entry() -> usize {
+        \\    return @sizeOf(Foo);
+        \\}
+    ,
+        ".tmp_source.zig:1:13: error: enums must have 1 or more fields");
+
+    cases.add("enum value already taken",
+        \\const MultipleChoice = enum(u32) {
+        \\    A = 20,
+        \\    B = 40,
+        \\    C = 60,
+        \\    D = 1000,
+        \\    E = 60,
+        \\};
+        \\export fn entry() {
+        \\    var x = MultipleChoice.C;
+        \\}
+    ,
+        ".tmp_source.zig:6:9: error: enum tag value 60 already taken",
+        ".tmp_source.zig:4:9: note: other occurrence here");
 }