Merge branch 'impl-1107' of https://github.com/emekoi/zig into emekoi-impl-1107

doc/langref.html.in

@@ -3016,6 +3016,7 @@ test "switch on tagged union" {
         A: u32,
         C: Point,
         D,
+        E: u32,
     };
 
     var a = Item{ .C = Point{ .x = 1, .y = 2 } };
@@ -3023,8 +3024,9 @@ test "switch on tagged union" {
     // Switching on more complex enums is allowed.
     const b = switch (a) {
         // A capture group is allowed on a match, and will return the enum
-        // value matched.
-        Item.A => |item| item,
+        // value matched. If the payloads of both cases are the same
+        // they can be put into the same switch prong.
+        Item.A, Item.E => |item| item,
 
         // A reference to the matched value can be obtained using `*` syntax.
         Item.C => |*item| blk: {

src/ir.cpp

@@ -19230,10 +19230,6 @@ static IrInstruction *ir_analyze_instruction_switch_var(IrAnalyze *ira, IrInstru
         assert(enum_type != nullptr);
         assert(enum_type->id == ZigTypeIdEnum);
 
-        if (instruction->prongs_len != 1) {
-            return target_value_ptr;
-        }
-
         IrInstruction *prong_value = instruction->prongs_ptr[0]->child;
         if (type_is_invalid(prong_value->value.type))
             return ira->codegen->invalid_instruction;
@@ -19248,6 +19244,40 @@ static IrInstruction *ir_analyze_instruction_switch_var(IrAnalyze *ira, IrInstru
 
         TypeUnionField *field = find_union_field_by_tag(target_type, &prong_val->data.x_enum_tag);
 
+        if (instruction->prongs_len != 1) {
+            ErrorMsg *invalid_payload = nullptr;
+            Buf *invalid_payload_list = nullptr;
+
+            for (size_t i = 1; i < instruction->prongs_len; i++) {
+                IrInstruction *casted_prong_value = ir_implicit_cast(ira, instruction->prongs_ptr[i]->child, enum_type);
+                if (type_is_invalid(casted_prong_value->value.type))
+                    return ira->codegen->invalid_instruction;
+                
+                ConstExprValue *next_prong = ir_resolve_const(ira, casted_prong_value, UndefBad);
+                if (!next_prong)
+                    return ira->codegen->invalid_instruction;
+
+                ZigType *payload = find_union_field_by_tag(target_type, &next_prong->data.x_enum_tag)->type_entry;
+
+                if (field->type_entry != payload) {
+                    if (!invalid_payload) {
+                        invalid_payload = ir_add_error(ira, &instruction->base,
+                            buf_sprintf("switch prong contains cases with different payloads"));
+                        invalid_payload_list = buf_sprintf("payload types are %s", buf_ptr(&field->type_entry->name));
+                    }
+
+                    if (i == instruction->prongs_len - 1)
+                        buf_append_buf(invalid_payload_list, buf_sprintf(" and %s", buf_ptr(&payload->name)));
+                    else
+                        buf_append_buf(invalid_payload_list, buf_sprintf(", %s", buf_ptr(&payload->name)));
+                }
+            }
+
+            if (invalid_payload)
+                add_error_note(ira->codegen, invalid_payload,
+                    ((IrInstruction*)instruction)->source_node, invalid_payload_list);
+        }
+
         if (instr_is_comptime(target_value_ptr)) {
             ConstExprValue *target_val_ptr = ir_resolve_const(ira, target_value_ptr, UndefBad);
             if (!target_value_ptr)

test/compile_errors.zig

@@ -6073,4 +6073,21 @@ pub fn addCases(cases: *tests.CompileErrorContext) void {
         "tmp.zig:5:30: error: expression value is ignored",
         "tmp.zig:9:30: error: expression value is ignored",
     );
+
+    cases.add(
+        "capture group on switch prong with different payloads",
+        \\const Union = union(enum) {
+        \\    A: usize,
+        \\    B: isize,
+        \\};
+        \\comptime {
+        \\    var u = Union{ .A = 8 };
+        \\    switch (u) {
+        \\        .A, .B => |e| unreachable,
+        \\    }
+        \\}
+    ,
+        "tmp.zig:8:20: error: switch prong contains cases with different payloads",
+        "tmp.zig:8:20: note: payload types are usize and isize",
+    );
 }

test/stage1/behavior/switch.zig

@@ -391,3 +391,21 @@ test "switch with null and T peer types and inferred result location type" {
     S.doTheTest(1);
     comptime S.doTheTest(1);
 }
+
+test "switch prongs with cases with identical payloads" {
+    const Union = union(enum) {
+        A: usize,
+        B: isize,
+        C: usize,
+    };
+    const S = struct {
+        fn doTheTest(u: Union) void {
+            switch (u) {
+                .A, .C => |e| expect(@typeOf(e) == usize),
+                .B => |e| expect(@typeOf(e) == isize),
+            }
+        }
+    };
+    S.doTheTest(Union{ .A = 8 });
+    comptime S.doTheTest(Union{ .B = -8 });
+}