Incorrect subscript resolution #1519

releasenotes.md

@@ -11,6 +11,7 @@
 ### Fixes
 - `Unsupported int[*] $x = { 1, 2, 3, 4 }` #1489.
 - Unexpected compile error using a typed constant with `copysign` #1517
+- Incorrect subscript resolution #1519.
 
 ### Stdlib changes
 - Remove unintended print of `char[]` as String

src/compiler/sema_expr.c

@@ -2846,13 +2846,40 @@ static inline bool sema_expr_analyse_subscript(SemaContext *context, Expr *expr,
 	// 3. Check failability due to value.
 	bool optional = IS_OPTIONAL(subscripted);
 
-	Type *underlying_type = type_flatten(subscripted->type);
+	Decl *overload = NULL;
+	Type *index_type = NULL;
+	Expr *current_expr;
+	Type *current_type = subscripted->type->canonical;
+	if (current_type == type_untypedlist)
+	{
+		current_expr = subscripted;
+	}
+	else
+	{
+		current_expr = sema_expr_find_index_type_or_overload_for_subscript(context, subscripted, check, &index_type, &overload);
+		if (!overload && !index_type && is_eval_ref)
+		{
+			// Maybe there is a [] overload?
+			if (sema_expr_find_index_type_or_overload_for_subscript(context, subscripted, check, &index_type, &overload))
+			{
+				if (check_valid) goto VALID_FAIL_POISON;
+				RETURN_SEMA_ERROR(expr, "A function or macro with '@operator(&[])' is not defined for %s, "
+				                        "so you need && to take the address of the temporary.",
+				                  type_quoted_error_string(subscripted->type));
+			}
+		}
+		if (!index_type)
+		{
+			if (check_valid) goto VALID_FAIL_POISON;
+			RETURN_SEMA_ERROR(expr, "Indexing a value of type %s is not possible.", type_quoted_error_string(subscripted->type));
+		}
+		if (!overload) current_type = type_flatten(current_expr->type);
+	}
 
-	Type *current_type = underlying_type;
 	assert(current_type == current_type->canonical);
 	int64_t index_value = -1;
 	bool start_from_end = expr->subscript_expr.index.start_from_end;
-	if (start_from_end && (underlying_type->type_kind == TYPE_POINTER || underlying_type->type_kind == TYPE_FLEXIBLE_ARRAY))
+	if (start_from_end && (current_type->type_kind == TYPE_POINTER || current_type->type_kind == TYPE_FLEXIBLE_ARRAY))
 	{
 		if (check_valid) goto VALID_FAIL_POISON;
 		RETURN_SEMA_ERROR(index, "Indexing from the end is not allowed for pointers "
@@ -2897,16 +2924,16 @@ static inline bool sema_expr_analyse_subscript(SemaContext *context, Expr *expr,
 			                  (long long) size - 1);
 		}
 	}
+
 	// 4. If we are indexing into a complist
-	if (underlying_type == type_untypedlist)
+	if (current_type == type_untypedlist)
 	{
 		if (is_eval_ref)
 		{
 			if (check_valid) goto VALID_FAIL_POISON;
 			RETURN_SEMA_ERROR(subscripted, "You need to use && to take the address of a temporary.");
 		}
 		// 4a. This may either be an initializer list or a CT value
-		Expr *current_expr = subscripted;
 		while (subscripted->expr_kind == EXPR_CT_IDENT) current_expr = current_expr->ct_ident_expr.decl->var.init_expr;
 
 		// 4b. Now we need to check that we actually have a valid type.
@@ -2921,29 +2948,6 @@ static inline bool sema_expr_analyse_subscript(SemaContext *context, Expr *expr,
 	}
 	if (!sema_cast_rvalue(context, subscripted)) return false;
 
-	Decl *overload = NULL;
-	Type *index_type = NULL;
-	Expr *current_expr = sema_expr_find_index_type_or_overload_for_subscript(context, subscripted, check, &index_type, &overload);
-	if (!index_type)
-	{
-		if (!overload && is_eval_ref)
-		{
-			// Maybe there is a [] overload?
-			if (sema_expr_find_index_type_or_overload_for_subscript(context,
-			                                                        subscripted,
-																	check,
-			                                                        &index_type,
-			                                                        &overload))
-			{
-				if (check_valid) goto VALID_FAIL_POISON;
-				RETURN_SEMA_ERROR(expr, "A function or macro with '@operator(&[])' is not defined for %s, "
-										"so you need && to take the address of the temporary.",
-										type_quoted_error_string(subscripted->type));
-			}
-		}
-		if (check_valid) goto VALID_FAIL_POISON;
-		RETURN_SEMA_ERROR(subscripted, "Cannot index %s.", type_quoted_error_string(subscripted->type));
-	}
 	if (overload)
 	{
 		if (start_from_end)

src/compiler/types.c

@@ -1079,6 +1079,7 @@ bool type_is_user_defined(Type *type)
 Type *type_get_indexed_type(Type *type)
 {
 	RETRY:
+	if (type == type_voidptr) return NULL;
 	switch (type->type_kind)
 	{
 		case TYPE_POINTER:

test/test_suite/expressions/fail_index_usize.c3

@@ -1,5 +1,5 @@
 fn void test(int* array, usz n)
 {
     array[n] = 33;
-    n[array] = 33; // #error: Cannot index
+    n[array] = 33; // #error: Indexing a value of type
 }

test/test_suite/subarrays/slice_offset.c3t

@@ -1,3 +1,4 @@
+// #target: macos-x64
 fn void test()
 {
     int[3] x = { 1, 2, 3 };

test/test_suite/subarrays/slice_offset_neg_end.c3t

@@ -1,4 +1,4 @@
-
+// #target: macos-x64
 fn void test()
 {
     int[3] x = { 1, 2, 3 };

test/test_suite/subarrays/slice_offset_neg_start.c3t

@@ -1,3 +1,4 @@
+// #target: macos-x64
 fn void test()
 {
     int[3] x = { 1, 2, 3 };

test/test_suite/subarrays/slice_start.c3t

@@ -1,3 +1,4 @@
+// #target: macos-x64
 fn void test()
 {
     int[3] x = { 1, 2, 3 };

test/test_suite/subarrays/subscript_check_1519.c3t

@@ -0,0 +1,37 @@
+// #target: macos-x64
+module test;
+import std::collections::list;
+macro @test_list(a)
+{
+  var $Type = $typeof(a);
+  $if $defined(a[0]) &&& $Type.typeid == List(<$typeof(a[0])>).typeid:
+    return 1;
+  $else
+    return 0;
+  $endif
+}
+
+fn int main(String[] args)
+{
+  DString str = dstring::new("test");
+  return @test_list(str);
+}
+
+/* #expect: test.ll
+
+define i32 @test.main(ptr %0, i64 %1) #0 {
+entry:
+  %args = alloca %"char[][]", align 8
+  %str = alloca ptr, align 8
+  %a = alloca ptr, align 8
+  store ptr %0, ptr %args, align 8
+  %ptradd = getelementptr inbounds i8, ptr %args, i64 8
+  store i64 %1, ptr %ptradd, align 8
+  %lo = load i64, ptr @std.core.mem.allocator.thread_allocator, align 8
+  %hi = load ptr, ptr getelementptr inbounds (i8, ptr @std.core.mem.allocator.thread_allocator, i64 8), align 8
+  %2 = call ptr @std.core.dstring.new(ptr @.str, i64 4, i64 %lo, ptr %hi)
+  store ptr %2, ptr %str, align 8
+  %3 = load ptr, ptr %str, align 8
+  store ptr %3, ptr %a, align 8
+  ret i32 0
+}

test/unit/stdlib/string.c3

@@ -8,12 +8,12 @@ fn void! test_clear() @test
 	s.append_repeat('x', 63);
 	assert(s.capacity() == 64);
 	assert(s.len() == 63);
-	char* addr = &s[0];
+	char* addr = (char*)s.str_view();
 	s.clear();
 	assert(s.capacity() == 64);
 	assert(s.len() == 0);
 	s.append_repeat('x', 63);
 	assert(s.capacity() == 64);
 	assert(s.len() == 63);
-	assert(addr == &s[0]);
+	assert(addr == (char*)s.str_view());
 }