Fix arrays of strings and NULLs

bootstrap_compiler/typecheck.c

@@ -1014,6 +1014,16 @@ static const Type *cast_array_members_to_a_common_type(const FunctionOrMethodTyp
             Append(&compatible_with_all, *t);
     }
 
+    if (compatible_with_all.len > 1) {
+        // Remove void* if exists, so that type of ["hello", NULL] becomes byte*[2]
+        for (int i = 0; i < compatible_with_all.len; i++) {
+            if (compatible_with_all.ptr[i] == voidPtrType) {
+                compatible_with_all.ptr[i] = compatible_with_all.ptr[--compatible_with_all.len];
+                break;
+            }
+        }
+    }
+
     if (compatible_with_all.len != 1) {
         List(char) namestr = {0};
         for (const Type **t = distinct.ptr; t < End(distinct); t++) {

compiler/build_cfg.jou

@@ -113,7 +113,7 @@ def add_unary_op(
     target: LocalVariable*,
 ) -> None:
     ins = CfInstruction{location = location, kind = op, destvar = target}
-    operands = [arg, NULL as LocalVariable*]
+    operands = [arg, NULL]
     ins.set_operands(operands)
     add_instruction(st, ins)
 
@@ -128,7 +128,7 @@ def add_binary_op(
     target: LocalVariable*,
 ) -> None:
     ins = CfInstruction{location = location, kind = op, destvar = target}
-    operands = [lhs, rhs, NULL as LocalVariable*]
+    operands = [lhs, rhs, NULL]
     ins.set_operands(operands)
     add_instruction(st, ins)
 
@@ -330,7 +330,7 @@ def build_class_field_pointer(
             assert sizeof(ins.fieldname) == sizeof(f->name)
             strcpy(ins.fieldname, f->name)
 
-            operands = [instance, NULL as LocalVariable*]
+            operands = [instance, NULL]
             ins.set_operands(operands)
 
             add_instruction(st, ins)
@@ -916,7 +916,7 @@ def build_assert(st: State*, assert_location: Location, assertion: AstAssertion*
         add_local_var(st, argtypes[0]),
         add_local_var(st, argtypes[1]),
         add_local_var(st, argtypes[2]),
-        NULL as LocalVariable*,
+        NULL,
     ]
 
     add_constant(st, assert_location, Constant{kind = ConstantKind::String, str = assertion->condition_str}, args[0])

compiler/typecheck.jou

@@ -888,7 +888,7 @@ global nth_result_buffer: byte[100]
 def nth(n: int) -> byte*:
     assert n >= 1
 
-    first_few = [NULL as byte*, "first", "second", "third", "fourth", "fifth", "sixth"]
+    first_few = [NULL, "first", "second", "third", "fourth", "fifth", "sixth"]
     if n < sizeof(first_few) / sizeof(first_few[0]):
         return first_few[n]
 
@@ -1075,6 +1075,13 @@ def cast_array_members_to_a_common_type(fom: FunctionOrMethodTypes*, error_locat
             assert compatible_with_all != NULL
             compatible_with_all[n_compatible_with_all++] = *t
 
+    if n_compatible_with_all > 1:
+        # Remove void* if exists, so that type of ["hello", NULL] becomes byte*[2]
+        for i = 0; i < n_compatible_with_all; i++:
+            if compatible_with_all[i] == voidPtrType:
+                compatible_with_all[i] = compatible_with_all[--n_compatible_with_all]
+                break
+
     if n_compatible_with_all != 1:
         size = 500L
         for t = distinct; t < &distinct[ndistinct]; t++:

examples/aoc2024/day21/part2.jou

@@ -32,35 +32,35 @@ def init_tables() -> None:
 
     #   ^ A
     # < v >
-    arrow_keypad_table['^']['^'] = ["A", NULL as byte*]
-    arrow_keypad_table['^']['A'] = [">A", NULL as byte*]
-    arrow_keypad_table['^']['<'] = ["v<A", NULL as byte*]
-    arrow_keypad_table['^']['v'] = ["vA", NULL as byte*]
+    arrow_keypad_table['^']['^'] = ["A", NULL]
+    arrow_keypad_table['^']['A'] = [">A", NULL]
+    arrow_keypad_table['^']['<'] = ["v<A", NULL]
+    arrow_keypad_table['^']['v'] = ["vA", NULL]
     arrow_keypad_table['^']['>'] = ["v>A", ">vA"]
 
-    arrow_keypad_table['A']['^'] = ["<A", NULL as byte*]
-    arrow_keypad_table['A']['A'] = ["A", NULL as byte*]
-    arrow_keypad_table['A']['<'] = ["v<<A", NULL as byte*]
+    arrow_keypad_table['A']['^'] = ["<A", NULL]
+    arrow_keypad_table['A']['A'] = ["A", NULL]
+    arrow_keypad_table['A']['<'] = ["v<<A", NULL]
     arrow_keypad_table['A']['v'] = ["v<A", "<vA"]
-    arrow_keypad_table['A']['>'] = ["vA", NULL as byte*]
+    arrow_keypad_table['A']['>'] = ["vA", NULL]
 
-    arrow_keypad_table['<']['^'] = [">^A", NULL as byte*]
-    arrow_keypad_table['<']['A'] = [">>^A", NULL as byte*]
-    arrow_keypad_table['<']['<'] = ["A", NULL as byte*]
-    arrow_keypad_table['<']['v'] = [">A", NULL as byte*]
-    arrow_keypad_table['<']['>'] = [">>A", NULL as byte*]
+    arrow_keypad_table['<']['^'] = [">^A", NULL]
+    arrow_keypad_table['<']['A'] = [">>^A", NULL]
+    arrow_keypad_table['<']['<'] = ["A", NULL]
+    arrow_keypad_table['<']['v'] = [">A", NULL]
+    arrow_keypad_table['<']['>'] = [">>A", NULL]
 
-    arrow_keypad_table['v']['^'] = ["^A", NULL as byte*]
+    arrow_keypad_table['v']['^'] = ["^A", NULL]
     arrow_keypad_table['v']['A'] = [">^A", "^>A"]
-    arrow_keypad_table['v']['<'] = ["<A", NULL as byte*]
-    arrow_keypad_table['v']['v'] = ["A", NULL as byte*]
-    arrow_keypad_table['v']['>'] = [">A", NULL as byte*]
+    arrow_keypad_table['v']['<'] = ["<A", NULL]
+    arrow_keypad_table['v']['v'] = ["A", NULL]
+    arrow_keypad_table['v']['>'] = [">A", NULL]
 
     arrow_keypad_table['>']['^'] = ["<^A", "^<A"]
-    arrow_keypad_table['>']['A'] = ["^A", NULL as byte*]
-    arrow_keypad_table['>']['<'] = ["<<A", NULL as byte*]
-    arrow_keypad_table['>']['v'] = ["<A", NULL as byte*]
-    arrow_keypad_table['>']['>'] = ["A", NULL as byte*]
+    arrow_keypad_table['>']['A'] = ["^A", NULL]
+    arrow_keypad_table['>']['<'] = ["<<A", NULL]
+    arrow_keypad_table['>']['v'] = ["<A", NULL]
+    arrow_keypad_table['>']['>'] = ["A", NULL]
 
     # 7 8 9
     # 4 5 6

tests/should_succeed/array.jou

@@ -42,4 +42,13 @@ def main() -> int:
     increment(foo as int*)  # same cast explicitly
     printf("%d %d %d\n", foo[0], foo[1], foo[2])  # Output: 7 5 6
 
+    # corner case: byte* <--> void* can be converted both ways, use byte*
+    strings = ["hello", NULL, "world", NULL]
+    printf("%s %s\n", strings[0], strings[2])  # Output: hello world
+    # Output: strings[1] is NULL
+    # Output: strings[3] is NULL
+    for i = 0; i < 4; i++:
+        if strings[i] == NULL:
+            printf("strings[%d] is NULL\n", i)
+
     return 0

tests/wrong_type/array_mixed_types_ptr.jou

@@ -1,9 +1,3 @@
 def foo() -> None:
-    # When we make an array of int* and void*:
-    #   - we could cast int* to void*, and get an array of void*
-    #   - we could cast void* to int*, and get an array of int*
-    #
-    # Because the compiler cannot be sure what you want, it refuses to
-    # guess and instead errors.
     a = 1
-    x = [&a, &a as void*]  # Error: array items have different types (int*, void*)
+    x = [&a, "hello"]  # Error: array items have different types (int*, byte*)