Merge pull request #2459 from LemonBoy/enum-num-um-m

Signed types for enum tags

3 files changed, 102 insertions, 70 deletions

diff --git a/src/analyze.cpp b/src/analyze.cpp
index c441676e77..57244aba6a 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -1908,6 +1908,18 @@ static Error resolve_union_type(CodeGen *g, ZigType *union_type) {
     return ErrorNone;
 }
 
+static bool type_is_valid_extern_enum_tag(CodeGen *g, ZigType *ty) {
+    // Only integer types are allowed by the C ABI
+    if(ty->id != ZigTypeIdInt)
+        return false;
+
+    // According to the ANSI C standard the enumeration type should be either a
+    // signed char, a signed integer or an unsigned one. But GCC/Clang allow
+    // other integral types as a compiler extension so let's accomodate them
+    // aswell.
+    return type_allowed_in_extern(g, ty);
+}
+
 static Error resolve_enum_zero_bits(CodeGen *g, ZigType *enum_type) {
     assert(enum_type->id == ZigTypeIdEnum);
 
@@ -1965,7 +1977,6 @@ static Error resolve_enum_zero_bits(CodeGen *g, ZigType *enum_type) {
     enum_type->abi_size = tag_int_type->abi_size;
     enum_type->abi_align = tag_int_type->abi_align;
 
-    // TODO: Are extern enums allowed to have an init_arg_expr?
     if (decl_node->data.container_decl.init_arg_expr != nullptr) {
         ZigType *wanted_tag_int_type = analyze_type_expr(g, scope, decl_node->data.container_decl.init_arg_expr);
         if (type_is_invalid(wanted_tag_int_type)) {
@@ -1974,24 +1985,29 @@ static Error resolve_enum_zero_bits(CodeGen *g, ZigType *enum_type) {
             enum_type->data.enumeration.is_invalid = true;
             add_node_error(g, decl_node->data.container_decl.init_arg_expr,
                 buf_sprintf("expected integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
-        } else if (wanted_tag_int_type->data.integral.is_signed) {
+        } else if (enum_type->data.enumeration.layout == ContainerLayoutExtern &&
+                   !type_is_valid_extern_enum_tag(g, wanted_tag_int_type)) {
             enum_type->data.enumeration.is_invalid = true;
-            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
-                buf_sprintf("expected unsigned integer, found '%s'", buf_ptr(&wanted_tag_int_type->name)));
-        } else if (wanted_tag_int_type->data.integral.bit_count < tag_int_type->data.integral.bit_count) {
-            enum_type->data.enumeration.is_invalid = true;
-            add_node_error(g, decl_node->data.container_decl.init_arg_expr,
-                buf_sprintf("'%s' too small to hold all bits; must be at least '%s'",
-                    buf_ptr(&wanted_tag_int_type->name), buf_ptr(&tag_int_type->name)));
+            ErrorMsg *msg = add_node_error(g, decl_node->data.container_decl.init_arg_expr,
+                buf_sprintf("'%s' is not a valid tag type for an extern enum",
+                            buf_ptr(&wanted_tag_int_type->name)));
+            add_error_note(g, msg, decl_node->data.container_decl.init_arg_expr,
+                buf_sprintf("any integral type of size 8, 16, 32, 64 or 128 bit is valid"));
         } else {
             tag_int_type = wanted_tag_int_type;
         }
     }
+
     enum_type->data.enumeration.tag_int_type = tag_int_type;
     enum_type->size_in_bits = tag_int_type->size_in_bits;
     enum_type->abi_size = tag_int_type->abi_size;
     enum_type->abi_align = tag_int_type->abi_align;
 
+    BigInt bi_one;
+    bigint_init_unsigned(&bi_one, 1);
+
+    TypeEnumField *last_enum_field = nullptr;
+
     for (uint32_t field_i = 0; field_i < field_count; field_i += 1) {
         AstNode *field_node = decl_node->data.container_decl.fields.at(field_i);
         TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_i];
@@ -2017,60 +2033,58 @@ static Error resolve_enum_zero_bits(CodeGen *g, ZigType *enum_type) {
 
         AstNode *tag_value = field_node->data.struct_field.value;
 
-        // In this first pass we resolve explicit tag values.
-        // In a second pass we will fill in the unspecified ones.
         if (tag_value != nullptr) {
+            // A user-specified value is available
             ConstExprValue *result = analyze_const_value(g, scope, tag_value, tag_int_type, nullptr);
             if (type_is_invalid(result->type)) {
                 enum_type->data.enumeration.is_invalid = true;
                 continue;
             }
+
             assert(result->special != ConstValSpecialRuntime);
-            assert(result->type->id == ZigTypeIdInt ||
-                   result->type->id == ZigTypeIdComptimeInt);
-            auto entry = occupied_tag_values.put_unique(result->data.x_bigint, tag_value);
-            if (entry == nullptr) {
-                bigint_init_bigint(&type_enum_field->value, &result->data.x_bigint);
+            assert(result->type->id == ZigTypeIdInt || result->type->id == ZigTypeIdComptimeInt);
+
+            bigint_init_bigint(&type_enum_field->value, &result->data.x_bigint);
+        } else {
+            // No value was explicitly specified: allocate the last value + 1
+            // or, if this is the first element, zero
+            if (last_enum_field != nullptr) {
+                bigint_add(&type_enum_field->value, &last_enum_field->value, &bi_one);
             } else {
-                Buf *val_buf = buf_alloc();
-                bigint_append_buf(val_buf, &result->data.x_bigint, 10);
+                bigint_init_unsigned(&type_enum_field->value, 0);
+            }
 
-                ErrorMsg *msg = add_node_error(g, tag_value,
-                        buf_sprintf("enum tag value %s already taken", buf_ptr(val_buf)));
-                add_error_note(g, msg, entry->value,
-                        buf_sprintf("other occurrence here"));
+            // Make sure we can represent this number with tag_int_type
+            if (!bigint_fits_in_bits(&type_enum_field->value,
+                                     tag_int_type->size_in_bits,
+                                     tag_int_type->data.integral.is_signed)) {
                 enum_type->data.enumeration.is_invalid = true;
-                continue;
+
+                Buf *val_buf = buf_alloc();
+                bigint_append_buf(val_buf, &type_enum_field->value, 10);
+                add_node_error(g, field_node,
+                    buf_sprintf("enumeration value %s too large for type '%s'",
+                        buf_ptr(val_buf), buf_ptr(&tag_int_type->name)));
+
+                break;
             }
         }
-    }
 
-    // Now iterate again and populate the unspecified tag values
-    uint32_t next_maybe_unoccupied_index = 0;
+        // Make sure the value is unique
+        auto entry = occupied_tag_values.put_unique(type_enum_field->value, field_node);
+        if (entry != nullptr) {
+            enum_type->data.enumeration.is_invalid = true;
 
-    for (uint32_t field_i = 0; field_i < field_count; field_i += 1) {
-        AstNode *field_node = decl_node->data.container_decl.fields.at(field_i);
-        TypeEnumField *type_enum_field = &enum_type->data.enumeration.fields[field_i];
-        AstNode *tag_value = field_node->data.struct_field.value;
+            Buf *val_buf = buf_alloc();
+            bigint_append_buf(val_buf, &type_enum_field->value, 10);
 
-        if (tag_value == nullptr) {
-            if (occupied_tag_values.size() == 0) {
-                bigint_init_unsigned(&type_enum_field->value, next_maybe_unoccupied_index);
-                next_maybe_unoccupied_index += 1;
-            } else {
-                BigInt proposed_value;
-                for (;;) {
-                    bigint_init_unsigned(&proposed_value, next_maybe_unoccupied_index);
-                    next_maybe_unoccupied_index += 1;
-                    auto entry = occupied_tag_values.put_unique(proposed_value, field_node);
-                    if (entry != nullptr) {
-                        continue;
-                    }
-                    break;
-                }
-                bigint_init_bigint(&type_enum_field->value, &proposed_value);
-            }
+            ErrorMsg *msg = add_node_error(g, field_node,
+                    buf_sprintf("enum tag value %s already taken", buf_ptr(val_buf)));
+            add_error_note(g, msg, entry->value,
+                    buf_sprintf("other occurrence here"));
         }
+
+        last_enum_field = type_enum_field;
     }
 
     enum_type->data.enumeration.zero_bits_loop_flag = false;
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index 6fc2fa65e7..297673235d 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -13,6 +13,19 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
     );
 
     cases.add(
+        "overflow in enum value allocation",
+        \\const Moo = enum(u8) {
+        \\    Last = 255,
+        \\    Over,
+        \\};
+        \\pub fn main() void {
+        \\  var y = Moo.Last;
+        \\}
+    ,
+        "tmp.zig:3:5: error: enumeration value 256 too large for type 'u8'",
+    );
+
+    cases.add(
         "attempt to cast enum literal to error",
         \\export fn entry() void {
         \\    switch (error.Hi) {
@@ -5383,8 +5396,7 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         "tmp.zig:12:20: note: referenced here",
     );
 
-    cases.add(
-        "specify enum tag type that is too small",
+    cases.add("specify enum tag type that is too small",
         \\const Small = enum (u2) {
         \\    One,
         \\    Two,
@@ -5396,9 +5408,7 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\export fn entry() void {
         \\    var x = Small.One;
         \\}
-    ,
-        "tmp.zig:1:21: error: 'u2' too small to hold all bits; must be at least 'u3'",
-    );
+    , "tmp.zig:6:5: error: enumeration value 4 too large for type 'u2'");
 
     cases.add(
         "specify non-integer enum tag type",
@@ -5449,22 +5459,6 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
     );
 
     cases.add(
-        "non unsigned integer enum tag type",
-        \\const Small = enum(i2) {
-        \\    One,
-        \\    Two,
-        \\    Three,
-        \\    Four,
-        \\};
-        \\
-        \\export fn entry() void {
-        \\    var y = Small.Two;
-        \\}
-    ,
-        "tmp.zig:1:20: error: expected unsigned integer, found 'i2'",
-    );
-
-    cases.add(
         "struct fields with value assignments",
         \\const MultipleChoice = struct {
         \\    A: i32 = 20,
@@ -5522,8 +5516,8 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         \\    var x = MultipleChoice.C;
         \\}
     ,
-        "tmp.zig:6:9: error: enum tag value 60 already taken",
-        "tmp.zig:4:9: note: other occurrence here",
+        "tmp.zig:6:5: error: enum tag value 60 already taken",
+        "tmp.zig:4:5: note: other occurrence here",
     );
 
     cases.add(
diff --git a/test/stage1/behavior/enum.zig b/test/stage1/behavior/enum.zig
index 70515ec35b..8a5edaa3dd 100644
--- a/test/stage1/behavior/enum.zig
+++ b/test/stage1/behavior/enum.zig
@@ -938,3 +938,27 @@ test "enum literal in array literal" {
     expect(array[0] == .one);
     expect(array[1] == .two);
 }
+
+test "signed integer as enum tag" {
+    const SignedEnum = enum(i2) {
+        A0 = -1,
+        A1 = 0,
+        A2 = 1,
+    };
+
+    expect(@enumToInt(SignedEnum.A0) == -1);
+    expect(@enumToInt(SignedEnum.A1) == 0);
+    expect(@enumToInt(SignedEnum.A2) == 1);
+}
+
+test "enum value allocation" {
+    const LargeEnum = enum(u32) {
+        A0 = 0x80000000,
+        A1,
+        A2,
+    };
+
+    expect(@enumToInt(LargeEnum.A0) == 0x80000000);
+    expect(@enumToInt(LargeEnum.A1) == 0x80000001);
+    expect(@enumToInt(LargeEnum.A2) == 0x80000002);
+}