- Add a.$eval($field) as a variant of a.$field.

lerno · lerno · commit 10025bdcb720 · 2026-05-26T23:22:11.000+02:00
diff --git a/releasenotes.md b/releasenotes.md
@@ -5,6 +5,7 @@
 ### Changes / improvements
 - Add `$$PROJECT_PATH`, accessible through `env::PROJECT_PATH`.
 - Deprecate `$field.get(a)` and `$field.set(a, b)`. Replaced by `a.$field` and `a.$field = b`.
+- Add `a.$eval($field)` as a variant of `a.$field`.
 
 ### Stdlib changes
 - Add math::TAU / math::TWO_PI
diff --git a/src/compiler/sema_expr.c b/src/compiler/sema_expr.c
@@ -370,22 +370,27 @@ Expr *sema_resolve_string_ident(SemaContext *context, Expr *inner, bool report_m
 	return NULL;
 }
 
-Expr *sema_ct_eval_expr(SemaContext *context, CtEvalKind eval_kind, Expr *inner, bool report_missing)
+Expr *sema_ct_eval_expr(SemaContext *context, CtEvalKind eval_kind, Expr *inner, bool report_missing, bool* was_reflect)
 {
 	if (!sema_analyse_ct_expr(context, inner)) return NULL;
 	if (!expr_is_const_string(inner))
 	{
+		if (was_reflect && inner->resolve_status == RESOLVE_DONE && expr_is_const_reflection(inner))
+		{
+			*was_reflect = true;
+			return inner;
+		}
 		switch (eval_kind)
 		{
 			case CT_EVAL_IDENTIFIER:
 				RETURN_VAL_SEMA_ERROR(poisoned_expr, inner, "'$eval' expects a constant string as the argument.");
 			case CT_EVAL_IMPLICIT_IDENTIFIER:
-				if (inner->resolve_status == RESOLVE_DONE && expr_is_const_reflection(inner)) return inner;
 				RETURN_VAL_SEMA_ERROR(poisoned_expr, inner, "A constant string was expected as the argument.");
 			default:
 				UNREACHABLE
 		}
 	}
+	if (was_reflect) *was_reflect = false;
 	return sema_resolve_string_ident(context, inner, report_missing);
 }
 
@@ -3646,7 +3651,7 @@ INLINE bool sema_expr_analyse_lookup(SemaContext *context, Expr *expr, Expr *tag
 	if (!sema_analyse_expr_rvalue(context, key)) return false;
 	ArrayIndex index;
 
-	Expr *ident = sema_expr_resolve_access_child(context, args[0], NULL, false);
+	Expr *ident = sema_expr_resolve_access_child(context, args[0], NULL, NULL);
 	if (!ident) return false;
 	if (ident->expr_kind != EXPR_UNRESOLVED_IDENTIFIER) RETURN_SEMA_ERROR(expr, "This is not a field.");
 	const char *child = ident->unresolved_ident_expr.ident;
@@ -4987,7 +4992,7 @@ static inline bool sema_expr_analyse_slice(SemaContext *context, Expr *expr)
  * 5. .$ident -> resolve as `$eval($ident)`
  * 6. .$Type -> It is a child to resolve as CT type param
  */
- Expr *sema_expr_resolve_access_child(SemaContext *context, Expr *child, bool *missing, bool allow_reflect)
+ Expr *sema_expr_resolve_access_child(SemaContext *context, Expr *child, bool *missing, bool *was_reflect)
 {
 	 SourceLocId loc = child->loc;
 	 bool in_hash = false;
@@ -5009,15 +5014,15 @@ static inline bool sema_expr_analyse_slice(SemaContext *context, Expr *expr)
 			return child;
 		case EXPR_CT_IDENT:
 		{
-			Expr *result = sema_ct_eval_expr(context, CT_EVAL_IMPLICIT_IDENTIFIER, child, missing == NULL);
+			Expr *result = sema_ct_eval_expr(context, CT_EVAL_IMPLICIT_IDENTIFIER, child, missing == NULL, was_reflect);
 			if (!expr_ok(result)) return NULL;
 			if (!result)
 			{
 				if (missing) *missing = true;
 				return NULL;
 			}
 			expr_replace(child, result);
-			if (result->resolve_status == RESOLVE_DONE && expr_is_const_reflection(result)) return child;
+			if (was_reflect && *was_reflect) return child;
 			goto RETRY;
 		}
 		case EXPR_TYPEINFO:
@@ -5027,14 +5032,15 @@ static inline bool sema_expr_analyse_slice(SemaContext *context, Expr *expr)
 		{
 			ASSERT_SPAN(child, child->resolve_status != RESOLVE_DONE);
 			// Only report missing if missing var is NULL
-			Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, child->inner_expr, missing == NULL);
+			Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, child->inner_expr, missing == NULL, was_reflect);
 			if (!expr_ok(result)) return NULL;
 			if (!result)
 			{
 				if (missing) *missing = true;
 				return NULL;
 			}
 			expr_replace(child, result);
+			if (was_reflect && *was_reflect) return child;
 			goto RETRY;
 		}
 		default:
@@ -6718,15 +6724,16 @@ static inline bool sema_expr_analyse_access(SemaContext *context, Expr *expr, bo
 	if (child->expr_kind == EXPR_TYPEINFO) RETURN_SEMA_ERROR(child, "A type can't appear here.");
 
 	// 3. Find the actual token.
-	Expr *identifier = sema_expr_resolve_access_child(context, child, missing_ref, true);
+	bool is_reflect = false;
+	Expr *identifier = sema_expr_resolve_access_child(context, child, missing_ref, &is_reflect);
 	if (!identifier) return false;
 	Decl *member;
 	Decl *decl;
 	Expr *current_parent;
 	bool optional;
 	const char *kw;
 	Type *underlying_type;
-	if (identifier->resolve_status == RESOLVE_DONE && expr_is_const_reflection(identifier))
+	if (is_reflect)
 	{
 		Expr *reflect = identifier->const_expr.reflection;
 		if (!expr_is_const_member(reflect)) RETURN_SEMA_ERROR(identifier, "Expected a member reference.");
@@ -10717,7 +10724,7 @@ static inline bool sema_expr_analyse_decl_element(SemaContext *context, Designat
 		*member_ref = NULL;
 		return true;
 	}
-	Expr *field = sema_expr_resolve_access_child(context, element->field_expr, is_missing, false);
+	Expr *field = sema_expr_resolve_access_child(context, element->field_expr, is_missing, NULL);
 	if (!field) return false;
 	if (field->expr_kind != EXPR_UNRESOLVED_IDENTIFIER) RETURN_SEMA_ERROR(field, "Expected an identifier here.");
 	const char *kw = field->unresolved_ident_expr.ident;
@@ -11480,7 +11487,7 @@ static inline bool sema_expr_analyse_ct_defined(SemaContext *context, Expr *expr
 			}
 			case EXPR_CT_EVAL:
 			{
-				Expr *eval = sema_ct_eval_expr(active_context, CT_EVAL_IDENTIFIER, main_expr->inner_expr, false);
+				Expr *eval = sema_ct_eval_expr(active_context, CT_EVAL_IDENTIFIER, main_expr->inner_expr, false, NULL);
 				if (!expr_ok(eval)) return false;
 				if (eval)
 				{
@@ -11785,7 +11792,7 @@ static inline bool sema_expr_analyse_ct_stringify(SemaContext *context, Expr *ex
 
 static inline bool sema_expr_resolve_ct_eval(SemaContext *context, Expr *expr)
 {
-	Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, expr->inner_expr, true);
+	Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, expr->inner_expr, true, NULL);
 	if (!result) return false;
 	if (result->expr_kind == EXPR_TYPEINFO)
 	{
diff --git a/src/compiler/sema_initializers.c b/src/compiler/sema_initializers.c
@@ -1416,7 +1416,7 @@ static Decl *sema_resolve_element_for_name(SemaContext *context, Decl **decls, D
 {
 	DesignatorElement *element = (*elements_ref)[*index];
 
-	Expr *field = sema_expr_resolve_access_child(context, element->field_expr, NULL, false);
+	Expr *field = sema_expr_resolve_access_child(context, element->field_expr, NULL, NULL);
 	if (!field) return poisoned_decl;
 
 	if (field->expr_kind != EXPR_UNRESOLVED_IDENTIFIER)
diff --git a/src/compiler/sema_internal.h b/src/compiler/sema_internal.h
@@ -88,7 +88,7 @@ void sema_analysis_pass_lambda(Module *module);
 void sema_analyze_stage(Module *module, AnalysisStage stage);
 void sema_trace_liveness(void);
 
-Expr *sema_expr_resolve_access_child(SemaContext *context, Expr *child, bool *missing, bool allow_reflect);
+Expr *sema_expr_resolve_access_child(SemaContext *context, Expr *child, bool *missing, bool *was_reflect);
 
 bool sema_analyse_expr_lvalue(SemaContext *context, Expr *expr, bool *failed_ref);
 
@@ -110,7 +110,7 @@ void sema_add_methods_to_decl_stack(SemaContext *context, Decl *decl);
 bool sema_expr_analyse_macro_call(SemaContext *context, Expr *call_expr, Expr *struct_var, Decl *decl, bool call_var_optional, bool *no_match_ref);
 Expr *sema_expr_analyse_ct_arg_index(SemaContext *context, Expr *index_expr);
 
-Expr *sema_ct_eval_expr(SemaContext *context, CtEvalKind eval_kind, Expr *inner, bool report_missing);
+Expr *sema_ct_eval_expr(SemaContext *context, CtEvalKind eval_kind, Expr *inner, bool report_missing, bool *was_reflect);
 Expr *sema_resolve_string_ident(SemaContext *context, Expr *inner, bool report_missing);
 bool sema_analyse_asm(SemaContext *context, AsmInlineBlock *block, Ast *asm_stmt);
 bool sema_expr_analyse_sprintf(SemaContext *context, Expr *expr, Expr *format_string, Expr **args, unsigned num_args);
diff --git a/test/test_suite/bitstruct/bitstruct_with_get_set.c3t b/test/test_suite/bitstruct/bitstruct_with_get_set.c3t
@@ -11,8 +11,7 @@ fn sz? Foo.to_format(&self, Formatter *f) @dynamic => io::struct_to_format(*self
 fn int main()
 {
 	Foo d = { 1, 11 };
-	var $member = Foo::members[0];
-	d.$member = 3;
+	d.$eval(Foo::members[0]) = 3;
 	return 0;
 }
 
diff --git a/test/test_suite/compile_time_introspection/membersof_enum.c3t b/test/test_suite/compile_time_introspection/membersof_enum.c3t
@@ -13,7 +13,7 @@ fn int main()
 	var $member0 = Foo::members[0];
 	var $member1 = Foo::members[1];
 	$assert Foo.ABC.$member0 == "Hello";
-	$assert Foo.DEF.$member0 == "World";
+	$assert Foo.DEF.$eval(Foo::members[0]) == "World";
 	$assert Foo.ABC.$member1 == 3;
 	$assert Foo.DEF.$member1 == -100;
 	$assert Foo::members[0].type == String;

Original file line number	Diff line number	Diff line change
`@@ -370,22 +370,27 @@ Expr sema_resolve_string_ident(SemaContext context, Expr *inner, bool report_m`
`370`	`370`	`return NULL;`
`371`	`371`	`}`
`372`	`372`
`373`		`-Expr sema_ct_eval_expr(SemaContext context, CtEvalKind eval_kind, Expr *inner, bool report_missing)`
	`373`	`+Expr sema_ct_eval_expr(SemaContext context, CtEvalKind eval_kind, Expr inner, bool report_missing, bool was_reflect)`
`374`	`374`	`{`
`375`	`375`	`if (!sema_analyse_ct_expr(context, inner)) return NULL;`
`376`	`376`	`if (!expr_is_const_string(inner))`
`377`	`377`	`{`
	`378`	`+ if (was_reflect && inner->resolve_status == RESOLVE_DONE && expr_is_const_reflection(inner))`
	`379`	`+ {`
	`380`	`+ *was_reflect = true;`
	`381`	`+ return inner;`
	`382`	`+ }`
`378`	`383`	`switch (eval_kind)`
`379`	`384`	`{`
`380`	`385`	`case CT_EVAL_IDENTIFIER:`
`381`	`386`	`RETURN_VAL_SEMA_ERROR(poisoned_expr, inner, "'$eval' expects a constant string as the argument.");`
`382`	`387`	`case CT_EVAL_IMPLICIT_IDENTIFIER:`
`383`		`- if (inner->resolve_status == RESOLVE_DONE && expr_is_const_reflection(inner)) return inner;`
`384`	`388`	`RETURN_VAL_SEMA_ERROR(poisoned_expr, inner, "A constant string was expected as the argument.");`
`385`	`389`	`default:`
`386`	`390`	`UNREACHABLE`
`387`	`391`	`}`
`388`	`392`	`}`
	`393`	`+ if (was_reflect) *was_reflect = false;`
`389`	`394`	`return sema_resolve_string_ident(context, inner, report_missing);`
`390`	`395`	`}`
`391`	`396`
`@@ -3646,7 +3651,7 @@ INLINE bool sema_expr_analyse_lookup(SemaContext context, Expr expr, Expr *tag`
`3646`	`3651`	`if (!sema_analyse_expr_rvalue(context, key)) return false;`
`3647`	`3652`	`ArrayIndex index;`
`3648`	`3653`
`3649`		`- Expr *ident = sema_expr_resolve_access_child(context, args[0], NULL, false);`
	`3654`	`+ Expr *ident = sema_expr_resolve_access_child(context, args[0], NULL, NULL);`
`3650`	`3655`	`if (!ident) return false;`
`3651`	`3656`	`if (ident->expr_kind != EXPR_UNRESOLVED_IDENTIFIER) RETURN_SEMA_ERROR(expr, "This is not a field.");`
`3652`	`3657`	`const char *child = ident->unresolved_ident_expr.ident;`
`@@ -4987,7 +4992,7 @@ static inline bool sema_expr_analyse_slice(SemaContext context, Expr expr)`
`4987`	`4992`	* 5. .$ident -> resolve as `$eval($ident)`
`4988`	`4993`	`* 6. .$Type -> It is a child to resolve as CT type param`
`4989`	`4994`	`*/`
`4990`		`- Expr sema_expr_resolve_access_child(SemaContext context, Expr child, bool missing, bool allow_reflect)`
	`4995`	`+ Expr sema_expr_resolve_access_child(SemaContext context, Expr child, bool missing, bool *was_reflect)`
`4991`	`4996`	`{`
`4992`	`4997`	`SourceLocId loc = child->loc;`
`4993`	`4998`	`bool in_hash = false;`
`@@ -5009,15 +5014,15 @@ static inline bool sema_expr_analyse_slice(SemaContext context, Expr expr)`
`5009`	`5014`	`return child;`
`5010`	`5015`	`case EXPR_CT_IDENT:`
`5011`	`5016`	`{`
`5012`		`- Expr *result = sema_ct_eval_expr(context, CT_EVAL_IMPLICIT_IDENTIFIER, child, missing == NULL);`
	`5017`	`+ Expr *result = sema_ct_eval_expr(context, CT_EVAL_IMPLICIT_IDENTIFIER, child, missing == NULL, was_reflect);`
`5013`	`5018`	`if (!expr_ok(result)) return NULL;`
`5014`	`5019`	`if (!result)`
`5015`	`5020`	`{`
`5016`	`5021`	`if (missing) *missing = true;`
`5017`	`5022`	`return NULL;`
`5018`	`5023`	`}`
`5019`	`5024`	`expr_replace(child, result);`
`5020`		`- if (result->resolve_status == RESOLVE_DONE && expr_is_const_reflection(result)) return child;`
	`5025`	`+ if (was_reflect && *was_reflect) return child;`
`5021`	`5026`	`goto RETRY;`
`5022`	`5027`	`}`
`5023`	`5028`	`case EXPR_TYPEINFO:`
`@@ -5027,14 +5032,15 @@ static inline bool sema_expr_analyse_slice(SemaContext context, Expr expr)`
`5027`	`5032`	`{`
`5028`	`5033`	`ASSERT_SPAN(child, child->resolve_status != RESOLVE_DONE);`
`5029`	`5034`	`// Only report missing if missing var is NULL`
`5030`		`- Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, child->inner_expr, missing == NULL);`
	`5035`	`+ Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, child->inner_expr, missing == NULL, was_reflect);`
`5031`	`5036`	`if (!expr_ok(result)) return NULL;`
`5032`	`5037`	`if (!result)`
`5033`	`5038`	`{`
`5034`	`5039`	`if (missing) *missing = true;`
`5035`	`5040`	`return NULL;`
`5036`	`5041`	`}`
`5037`	`5042`	`expr_replace(child, result);`
	`5043`	`+ if (was_reflect && *was_reflect) return child;`
`5038`	`5044`	`goto RETRY;`
`5039`	`5045`	`}`
`5040`	`5046`	`default:`
`@@ -6718,15 +6724,16 @@ static inline bool sema_expr_analyse_access(SemaContext context, Expr expr, bo`
`6718`	`6724`	`if (child->expr_kind == EXPR_TYPEINFO) RETURN_SEMA_ERROR(child, "A type can't appear here.");`
`6719`	`6725`
`6720`	`6726`	`// 3. Find the actual token.`
`6721`		`- Expr *identifier = sema_expr_resolve_access_child(context, child, missing_ref, true);`
	`6727`	`+ bool is_reflect = false;`
	`6728`	`+ Expr *identifier = sema_expr_resolve_access_child(context, child, missing_ref, &is_reflect);`
`6722`	`6729`	`if (!identifier) return false;`
`6723`	`6730`	`Decl *member;`
`6724`	`6731`	`Decl *decl;`
`6725`	`6732`	`Expr *current_parent;`
`6726`	`6733`	`bool optional;`
`6727`	`6734`	`const char *kw;`
`6728`	`6735`	`Type *underlying_type;`
`6729`		`- if (identifier->resolve_status == RESOLVE_DONE && expr_is_const_reflection(identifier))`
	`6736`	`+ if (is_reflect)`
`6730`	`6737`	`{`
`6731`	`6738`	`Expr *reflect = identifier->const_expr.reflection;`
`6732`	`6739`	`if (!expr_is_const_member(reflect)) RETURN_SEMA_ERROR(identifier, "Expected a member reference.");`
`@@ -10717,7 +10724,7 @@ static inline bool sema_expr_analyse_decl_element(SemaContext *context, Designat`
`10717`	`10724`	`*member_ref = NULL;`
`10718`	`10725`	`return true;`
`10719`	`10726`	`}`
`10720`		`- Expr *field = sema_expr_resolve_access_child(context, element->field_expr, is_missing, false);`
	`10727`	`+ Expr *field = sema_expr_resolve_access_child(context, element->field_expr, is_missing, NULL);`
`10721`	`10728`	`if (!field) return false;`
`10722`	`10729`	`if (field->expr_kind != EXPR_UNRESOLVED_IDENTIFIER) RETURN_SEMA_ERROR(field, "Expected an identifier here.");`
`10723`	`10730`	`const char *kw = field->unresolved_ident_expr.ident;`
`@@ -11480,7 +11487,7 @@ static inline bool sema_expr_analyse_ct_defined(SemaContext context, Expr expr`
`11480`	`11487`	`}`
`11481`	`11488`	`case EXPR_CT_EVAL:`
`11482`	`11489`	`{`
`11483`		`- Expr *eval = sema_ct_eval_expr(active_context, CT_EVAL_IDENTIFIER, main_expr->inner_expr, false);`
	`11490`	`+ Expr *eval = sema_ct_eval_expr(active_context, CT_EVAL_IDENTIFIER, main_expr->inner_expr, false, NULL);`
`11484`	`11491`	`if (!expr_ok(eval)) return false;`
`11485`	`11492`	`if (eval)`
`11486`	`11493`	`{`
`@@ -11785,7 +11792,7 @@ static inline bool sema_expr_analyse_ct_stringify(SemaContext context, Expr ex`
`11785`	`11792`
`11786`	`11793`	`static inline bool sema_expr_resolve_ct_eval(SemaContext context, Expr expr)`
`11787`	`11794`	`{`
`11788`		`- Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, expr->inner_expr, true);`
	`11795`	`+ Expr *result = sema_ct_eval_expr(context, CT_EVAL_IDENTIFIER, expr->inner_expr, true, NULL);`
`11789`	`11796`	`if (!result) return false;`
`11790`	`11797`	`if (result->expr_kind == EXPR_TYPEINFO)`
`11791`	`11798`	`{`
Original file line number	Diff line number	Diff line change
`@@ -1416,7 +1416,7 @@ static Decl sema_resolve_element_for_name(SemaContext context, Decl **decls, D`
`1416`	`1416`	`{`
`1417`	`1417`	`DesignatorElement element = (elements_ref)[*index];`
`1418`	`1418`
`1419`		`- Expr *field = sema_expr_resolve_access_child(context, element->field_expr, NULL, false);`
	`1419`	`+ Expr *field = sema_expr_resolve_access_child(context, element->field_expr, NULL, NULL);`
`1420`	`1420`	`if (!field) return poisoned_decl;`
`1421`	`1421`
`1422`	`1422`	`if (field->expr_kind != EXPR_UNRESOLVED_IDENTIFIER)`
Original file line number	Diff line number	Diff line change
`@@ -11,8 +11,7 @@ fn sz? Foo.to_format(&self, Formatter f) @dynamic => io::struct_to_format(self`
`11`	`11`	`fn int main()`
`12`	`12`	`{`
`13`	`13`	`Foo d = { 1, 11 };`
`14`		`- var $member = Foo::members[0];`
`15`		`- d.$member = 3;`
	`14`	`+ d.$eval(Foo::members[0]) = 3;`
`16`	`15`	`return 0;`
`17`	`16`	`}`
`18`	`17`