From bd9bc118db1996f7be359de87fc8303d4048f698 Mon Sep 17 00:00:00 2001
From: Christoffer Lerno <christoffer@aegik.com>
Date: Sat, 6 Sep 2025 16:18:33 +0200
Subject: [PATCH] Allow doc comments on individual struct members, faultdefs
 and enum values #2427.

---
 releasenotes.md                             |  1 +
 src/compiler/parse_global.c                 | 20 +++++++++-
 test/test_suite/errors/contracts_in_defs.c3 | 41 +++++++++++++++++++++
 3 files changed, 61 insertions(+), 1 deletion(-)
 create mode 100644 test/test_suite/errors/contracts_in_defs.c3

diff --git a/releasenotes.md b/releasenotes.md
index caeca685c..e7c75aab5 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -56,6 +56,7 @@
 - `$defined(#hash)` will not check the internal expression, just that `#hash` exists. Use `$defined((void)#hash)` for the old behaviour.
 - Added optional macro arguments using `macro foo(int x = ...)` which can be checked using `$defined(x)`.
 - Add compile time ternary `$val ??? <expr> : <expr>`.
+- Allow doc comments on individual struct members, faultdefs and enum values #2427.
 
 ### Fixes
 - List.remove_at would incorrectly trigger ASAN.
diff --git a/src/compiler/parse_global.c b/src/compiler/parse_global.c
index b65a8ee2c..fd3728b19 100644
--- a/src/compiler/parse_global.c
+++ b/src/compiler/parse_global.c
@@ -1728,7 +1728,22 @@ static inline bool parse_fn_parameter_list(ParseContext *c, Signature *signature
 
 // --- Parse types
 
-
+static bool parse_element_contract(ParseContext *c, const char *error)
+{
+	AstId contracts = 0;
+	if (!parse_contracts(c, &contracts)) return false;
+	if (!contracts) return true;
+	Ast *ast = astptr(contracts);
+	while (ast)
+	{
+		if (ast->ast_kind != AST_CONTRACT || ast->contract_stmt.kind != CONTRACT_COMMENT)
+		{
+			RETURN_PRINT_ERROR_AT(false, ast, "No constraints are allowed on %s.", error);
+		}
+		ast = astptrzero(ast->next);
+	}
+	return true;
+}
 /**
  * Expect pointer to after '{'
  *
@@ -1754,6 +1769,7 @@ static bool parse_struct_body(ParseContext *c, Decl *parent)
 	ArrayIndex index = 0;
 	while (!tok_is(c, TOKEN_RBRACE))
 	{
+		if (!parse_element_contract(c, "struct/union members")) return decl_poison(parent);
 		TokenType token_type = c->tok;
 		if (token_type == TOKEN_STRUCT || token_type == TOKEN_UNION || token_type == TOKEN_BITSTRUCT)
 		{
@@ -2476,6 +2492,7 @@ static inline Decl *parse_macro_declaration(ParseContext *c, AstId docs)
 
 static inline Decl *parse_fault(ParseContext *c)
 {
+	if (!parse_element_contract(c, "faults")) return poisoned_decl;
 	Decl *decl = decl_new(DECL_FAULT, symstr(c), c->span);
 	if (!consume_const_name(c, "fault")) return poisoned_decl;
 	if (!parse_attributes_for_global(c, decl)) return poisoned_decl;
@@ -2556,6 +2573,7 @@ static bool parse_enum_values(ParseContext *c, Decl*** values_ref, Visibility vi
 	Decl **values = NULL;
 	while (!try_consume(c, TOKEN_RBRACE))
 	{
+		if (!parse_element_contract(c, "enum values")) return false;
 		Decl *enum_const = decl_new(DECL_ENUM_CONSTANT, symstr(c), c->span);
 		if (is_const_enum) enum_const->enum_constant.is_raw = is_const_enum;
 		enum_const->visibility = visibility;
diff --git a/test/test_suite/errors/contracts_in_defs.c3 b/test/test_suite/errors/contracts_in_defs.c3
new file mode 100644
index 000000000..510d0234f
--- /dev/null
+++ b/test/test_suite/errors/contracts_in_defs.c3
@@ -0,0 +1,41 @@
+module test;
+import std;
+
+struct Foo
+{
+	<* hello *>
+	int a;
+	<* test *>
+	union
+	{
+		<* test2 *>
+		int b;
+	}
+	struct foo
+	{
+		<* baz *>
+		int g;
+	}
+}
+
+faultdef <* hello *> FOO;
+enum Abc
+{
+	<* test *>
+	XYZ
+}
+
+faultdef <* @require a > 0 *> FOO2; // #error: No constraints are allowed on faults
+enum Abc2
+{
+	<* @require a > 0 *> // #error: No constraints are allowed on enum values
+	XYZ
+}
+struct Test
+{
+	<* @require a > 0 *> // #error: No constraints are allowed on struct/union members
+	int a;
+}
+
+fn void main()
+{}
\ No newline at end of file