type_has_one_possible_value takes comptime struct fields into account

Before, type_has_one_possible_value would return false for the value
`.{1}`. But actually, that type is a tuple with a single comptime field.
Such a type, in fact, has one possible value.

This plus the corresponding adjustment to get_the_one_possible_value
solves #3878.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/analyze.cpp b/src/analyze.cpp
index e627eaf91b..14b9c25c07 100644
--- a/src/analyze.cpp
+++ b/src/analyze.cpp
@@ -5769,6 +5769,10 @@ OnePossibleValue type_has_one_possible_value(CodeGen *g, ZigType *type_entry) {
             type_entry->one_possible_value = OnePossibleValueNo;
             for (size_t i = 0; i < type_entry->data.structure.src_field_count; i += 1) {
                 TypeStructField *field = type_entry->data.structure.fields[i];
+                if (field->is_comptime) {
+                    // If this field is comptime then the field can only be one possible value
+                    continue;
+                }
                 OnePossibleValue opv = (field->type_entry != nullptr) ?
                     type_has_one_possible_value(g, field->type_entry) :
                     type_val_resolve_has_one_possible_value(g, field->type_val);
@@ -5825,6 +5829,10 @@ ZigValue *get_the_one_possible_value(CodeGen *g, ZigType *type_entry) {
         result->data.x_struct.fields = alloc_const_vals_ptrs(g, field_count);
         for (size_t i = 0; i < field_count; i += 1) {
             TypeStructField *field = struct_type->data.structure.fields[i];
+            if (field->is_comptime) {
+                copy_const_val(g, result->data.x_struct.fields[i], field->init_val);
+                continue;
+            }
             ZigType *field_type = resolve_struct_field_type(g, field);
             assert(field_type != nullptr);
             result->data.x_struct.fields[i] = get_the_one_possible_value(g, field_type);