Merge branch 'odin-lang:master' into master

17 files changed, 360 insertions, 120 deletions

diff --git a/src/build_settings.cpp b/src/build_settings.cpp
index 4c3f4b782..93168cf77 100644
--- a/src/build_settings.cpp
+++ b/src/build_settings.cpp
@@ -324,6 +324,18 @@ u64 get_vet_flag_from_name(String const &name) {
 	return VetFlag_NONE;
 }
 
+enum OptInFeatureFlags : u64 {
+	OptInFeatureFlag_NONE            = 0,
+	OptInFeatureFlag_DynamicLiterals = 1u<<0,
+};
+
+u64 get_feature_flag_from_name(String const &name) {
+	if (name == "dynamic-literals") {
+		return OptInFeatureFlag_DynamicLiterals;
+	}
+	return OptInFeatureFlag_NONE;
+}
+
 
 enum SanitizerFlags : u32 {
 	SanitizerFlag_NONE = 0,
@@ -429,7 +441,6 @@ struct BuildContext {
 	bool   ignore_unknown_attributes;
 	bool   no_bounds_check;
 	bool   no_type_assert;
-	bool   no_dynamic_literals;
 	bool   no_output_files;
 	bool   no_crt;
 	bool   no_rpath;
@@ -1855,11 +1866,6 @@ gb_internal bool init_build_paths(String init_filename) {
 		produces_output_file = true;
 	}
 
-	if (build_context.ODIN_DEFAULT_TO_NIL_ALLOCATOR ||
-	    build_context.ODIN_DEFAULT_TO_PANIC_ALLOCATOR) {
-		bc->no_dynamic_literals = true;
-	}
-
 	if (!produces_output_file) {
 		// Command doesn't produce output files. We're done.
 		return true;
diff --git a/src/check_decl.cpp b/src/check_decl.cpp
index 60eb030ff..1d792dad8 100644
--- a/src/check_decl.cpp
+++ b/src/check_decl.cpp
@@ -94,12 +94,14 @@ gb_internal Type *check_init_variable(CheckerContext *ctx, Entity *e, Operand *o
 				return nullptr;
 			}
 			if (e2->state.load() != EntityState_Resolved) {
-				gbString str = type_to_string(t);
-				defer (gb_string_free(str));
-				error(e->token, "Invalid use of a polymorphic type '%s' in %.*s", str, LIT(context_name));
-				e->type = t_invalid;
+				e->type = t;
 				return nullptr;
 			}
+			gbString str = type_to_string(t);
+			defer (gb_string_free(str));
+			error(operand->expr, "Invalid use of a non-specialized polymorphic type '%s' in %.*s", str, LIT(context_name));
+			e->type = t_invalid;
+			return nullptr;
 		} else if (is_type_empty_union(t)) {
 			gbString str = type_to_string(t);
 			defer (gb_string_free(str));
@@ -971,6 +973,43 @@ gb_internal void check_objc_methods(CheckerContext *ctx, Entity *e, AttributeCon
 	}
 }
 
+gb_internal void check_foreign_procedure(CheckerContext *ctx, Entity *e, DeclInfo *d) {
+	GB_ASSERT(e != nullptr);
+	GB_ASSERT(e->kind == Entity_Procedure);
+	String name = e->Procedure.link_name;
+
+	mutex_lock(&ctx->info->foreign_mutex);
+
+	auto *fp = &ctx->info->foreigns;
+	StringHashKey key = string_hash_string(name);
+	Entity **found = string_map_get(fp, key);
+	if (found && e != *found) {
+		Entity *f = *found;
+		TokenPos pos = f->token.pos;
+		Type *this_type = base_type(e->type);
+		Type *other_type = base_type(f->type);
+		if (is_type_proc(this_type) && is_type_proc(other_type)) {
+			if (!are_signatures_similar_enough(this_type, other_type)) {
+				error(d->proc_lit,
+				      "Redeclaration of foreign procedure '%.*s' with different type signatures\n"
+				      "\tat %s",
+				      LIT(name), token_pos_to_string(pos));
+			}
+		} else if (!signature_parameter_similar_enough(this_type, other_type)) {
+			error(d->proc_lit,
+			      "Foreign entity '%.*s' previously declared elsewhere with a different type\n"
+			      "\tat %s",
+			      LIT(name), token_pos_to_string(pos));
+		}
+	} else if (name == "main") {
+		error(d->proc_lit, "The link name 'main' is reserved for internal use");
+	} else {
+		string_map_set(fp, key, e);
+	}
+
+	mutex_unlock(&ctx->info->foreign_mutex);
+}
+
 gb_internal void check_proc_decl(CheckerContext *ctx, Entity *e, DeclInfo *d) {
 	GB_ASSERT(e->type == nullptr);
 	if (d->proc_lit->kind != Ast_ProcLit) {
@@ -1307,57 +1346,16 @@ gb_internal void check_proc_decl(CheckerContext *ctx, Entity *e, DeclInfo *d) {
 			name = e->Procedure.link_name;
 		}
 		Entity *foreign_library = init_entity_foreign_library(ctx, e);
-		
-		if (is_arch_wasm() && foreign_library != nullptr) {
-			String module_name = str_lit("env");
-			GB_ASSERT (foreign_library->kind == Entity_LibraryName);
-			if (foreign_library->LibraryName.paths.count != 1) {
-				error(foreign_library->token, "'foreign import' for '%.*s' architecture may only have one path, got %td",
-				      LIT(target_arch_names[build_context.metrics.arch]), foreign_library->LibraryName.paths.count);
-			}
-
-			if (foreign_library->LibraryName.paths.count >= 1) {
-				module_name = foreign_library->LibraryName.paths[0];
-			}
-
-			if (!string_ends_with(module_name, str_lit(".o"))) {
-				name = concatenate3_strings(permanent_allocator(), module_name, WASM_MODULE_NAME_SEPARATOR, name);
-			}
-		}
-
 		e->Procedure.is_foreign = true;
 		e->Procedure.link_name = name;
+		e->Procedure.foreign_library = foreign_library;
 
-		mutex_lock(&ctx->info->foreign_mutex);
-
-		auto *fp = &ctx->info->foreigns;
-		StringHashKey key = string_hash_string(name);
-		Entity **found = string_map_get(fp, key);
-		if (found && e != *found) {
-			Entity *f = *found;
-			TokenPos pos = f->token.pos;
-			Type *this_type = base_type(e->type);
-			Type *other_type = base_type(f->type);
-			if (is_type_proc(this_type) && is_type_proc(other_type)) {
-				if (!are_signatures_similar_enough(this_type, other_type)) {
-					error(d->proc_lit,
-					      "Redeclaration of foreign procedure '%.*s' with different type signatures\n"
-					      "\tat %s",
-					      LIT(name), token_pos_to_string(pos));
-				}
-			} else if (!signature_parameter_similar_enough(this_type, other_type)) {
-				error(d->proc_lit,
-				      "Foreign entity '%.*s' previously declared elsewhere with a different type\n"
-				      "\tat %s",
-				      LIT(name), token_pos_to_string(pos));
-			}
-		} else if (name == "main") {
-			error(d->proc_lit, "The link name 'main' is reserved for internal use");
+		if (is_arch_wasm() && foreign_library != nullptr) {
+			// NOTE(bill): this must be delayed because the foreign import paths might not be evaluated yet until much later
+			mpsc_enqueue(&ctx->info->foreign_decls_to_check, e);
 		} else {
-			string_map_set(fp, key, e);
+			check_foreign_procedure(ctx, e, d);
 		}
-
-		mutex_unlock(&ctx->info->foreign_mutex);
 	} else {
 		String name = e->token.string;
 		if (e->Procedure.link_name.len > 0) {
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index cc9483187..231ece2f4 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -3672,6 +3672,13 @@ gb_internal bool check_binary_array_expr(CheckerContext *c, Token op, Operand *x
 			}
 		}
 	}
+	if (is_type_simd_vector(x->type) && !is_type_simd_vector(y->type)) {
+		if (check_is_assignable_to(c, y, x->type)) {
+			if (check_binary_op(c, x, op)) {
+				return true;
+			}
+		}
+	}
 	return false;
 }
 
@@ -4556,6 +4563,19 @@ gb_internal void convert_to_typed(CheckerContext *c, Operand *operand, Type *tar
 		break;
 	}
 	
+	case Type_SimdVector: {
+		Type *elem = base_array_type(t);
+		if (check_is_assignable_to(c, operand, elem)) {
+			operand->mode = Addressing_Value;
+		} else {
+			operand->mode = Addressing_Invalid;
+			convert_untyped_error(c, operand, target_type);
+			return;
+		}
+
+		break;
+	}
+	
 	case Type_Matrix: {
 		Type *elem = base_array_type(t);
 		if (check_is_assignable_to(c, operand, elem)) {
@@ -8725,6 +8745,18 @@ gb_internal ExprKind check_basic_directive_expr(CheckerContext *c, Operand *o, A
 		error(node, "#caller_expression may only be used as a default argument parameter");
 		o->type = t_string;
 		o->mode = Addressing_Value;
+	} else if (name == "branch_location") {
+		if (!c->in_defer) {
+			error(node, "#branch_location may only be used within a 'defer' statement");
+		} else if (c->curr_proc_decl) {
+			Entity *e = c->curr_proc_decl->entity;
+			if (e != nullptr) {
+				GB_ASSERT(e->kind == Entity_Procedure);
+				e->Procedure.uses_branch_location = true;
+			}
+		}
+		o->type = t_source_code_location;
+		o->mode = Addressing_Value;
 	} else {
 		if (name == "location") {
 			init_core_source_code_location(c->checker);
@@ -9339,6 +9371,23 @@ gb_internal bool is_expr_inferred_fixed_array(Ast *type_expr) {
 	return false;
 }
 
+gb_internal bool check_for_dynamic_literals(CheckerContext *c, Ast *node, AstCompoundLit *cl) {
+	if (cl->elems.count > 0 && (check_feature_flags(c, node) & OptInFeatureFlag_DynamicLiterals) == 0) {
+		ERROR_BLOCK();
+		error(node, "Compound literals of dynamic types are disabled by default");
+		error_line("\tSuggestion: If you want to enable them for this specific file, add '#+feature dynamic-literals' at the top of the file\n");
+		error_line("\tWarning: Please understand that dynamic literals will implicitly allocate using the current 'context.allocator' in that scope\n");
+		if (build_context.ODIN_DEFAULT_TO_NIL_ALLOCATOR) {
+			error_line("\tWarning: As '-default-to-panic-allocator' has been set, the dynamic compound literal may not be initialized as expected\n");
+		} else if (build_context.ODIN_DEFAULT_TO_PANIC_ALLOCATOR) {
+			error_line("\tWarning: As '-default-to-panic-allocator' has been set, the dynamic compound literal may not be initialized as expected\n");
+		}
+		return false;
+	}
+
+	return cl->elems.count > 0;
+}
+
 gb_internal ExprKind check_compound_literal(CheckerContext *c, Operand *o, Ast *node, Type *type_hint) {
 	ExprKind kind = Expr_Expr;
 	ast_node(cl, CompoundLit, node);
@@ -9539,11 +9588,6 @@ gb_internal ExprKind check_compound_literal(CheckerContext *c, Operand *o, Ast *
 			elem_type = t->DynamicArray.elem;
 			context_name = str_lit("dynamic array literal");
 			is_constant = false;
-
-			if (!build_context.no_dynamic_literals) {
-				add_package_dependency(c, "runtime", "__dynamic_array_reserve");
-				add_package_dependency(c, "runtime", "__dynamic_array_append");
-			}
 		} else if (t->kind == Type_SimdVector) {
 			elem_type = t->SimdVector.elem;
 			context_name = str_lit("simd vector literal");
@@ -9718,8 +9762,9 @@ gb_internal ExprKind check_compound_literal(CheckerContext *c, Operand *o, Ast *
 
 
 		if (t->kind == Type_DynamicArray) {
-			if (build_context.no_dynamic_literals && cl->elems.count) {
-				error(node, "Compound literals of dynamic types have been disabled");
+			if (check_for_dynamic_literals(c, node, cl)) {
+				add_package_dependency(c, "runtime", "__dynamic_array_reserve");
+				add_package_dependency(c, "runtime", "__dynamic_array_append");
 			}
 		}
 
@@ -10108,9 +10153,7 @@ gb_internal ExprKind check_compound_literal(CheckerContext *c, Operand *o, Ast *
 			}
 		}
 
-		if (build_context.no_dynamic_literals && cl->elems.count) {
-			error(node, "Compound literals of dynamic types have been disabled");
-		} else {
+		if (check_for_dynamic_literals(c, node, cl)) {
 			add_map_reserve_dependencies(c);
 			add_map_set_dependencies(c);
 		}
diff --git a/src/check_type.cpp b/src/check_type.cpp
index 13a6125ca..44108ccbe 100644
--- a/src/check_type.cpp
+++ b/src/check_type.cpp
@@ -2440,8 +2440,12 @@ gb_internal bool check_procedure_type(CheckerContext *ctx, Type *type, Ast *proc
 	bool success = true;
 	isize specialization_count = 0;
 	Type *params  = check_get_params(c, c->scope, pt->params, &variadic, &variadic_index, &success, &specialization_count, operands);
-	Type *results = check_get_results(c, c->scope, pt->results);
 
+	bool no_poly_return = c->disallow_polymorphic_return_types;
+	c->disallow_polymorphic_return_types = c->scope == c->polymorphic_scope;
+	// NOTE(zen3ger): if the parapoly scope is the current proc's scope, then the return types shall not declare new poly vars
+	Type *results = check_get_results(c, c->scope, pt->results);
+	c->disallow_polymorphic_return_types = no_poly_return;
 
 	isize param_count = 0;
 	isize result_count = 0;
@@ -3383,6 +3387,9 @@ gb_internal bool check_type_internal(CheckerContext *ctx, Ast *e, Type **type, T
 		}
 		Type *t = alloc_type_generic(ctx->scope, 0, token.string, specific);
 		if (ctx->allow_polymorphic_types) {
+			if (ctx->disallow_polymorphic_return_types) {
+				error(ident, "Undeclared polymorphic parameter '%.*s' in return type", LIT(token.string));
+			}
 			Scope *ps = ctx->polymorphic_scope;
 			Scope *s = ctx->scope;
 			Scope *entity_scope = s;
diff --git a/src/checker.cpp b/src/checker.cpp
index b7cf343f8..5d3263789 100644
--- a/src/checker.cpp
+++ b/src/checker.cpp
@@ -542,6 +542,23 @@ gb_internal u64 check_vet_flags(Ast *node) {
 	return ast_file_vet_flags(file);
 }
 
+gb_internal u64 check_feature_flags(CheckerContext *c, Ast *node) {
+	AstFile *file = c->file;
+	if (file == nullptr &&
+	    c->curr_proc_decl &&
+	    c->curr_proc_decl->proc_lit) {
+		file = c->curr_proc_decl->proc_lit->file();
+	}
+	if (file == nullptr) {
+		file = node->file();
+	}
+	if (file != nullptr && file->feature_flags_set) {
+		return file->feature_flags;
+	}
+	return 0;
+}
+
+
 enum VettedEntityKind {
 	VettedEntity_Invalid,
 
@@ -1164,7 +1181,6 @@ gb_internal void init_universal(void) {
 	add_global_bool_constant("ODIN_NO_BOUNDS_CHECK",            build_context.no_bounds_check);
 	add_global_bool_constant("ODIN_NO_TYPE_ASSERT",             build_context.no_type_assert);
 	add_global_bool_constant("ODIN_DEFAULT_TO_PANIC_ALLOCATOR", bc->ODIN_DEFAULT_TO_PANIC_ALLOCATOR);
-	add_global_bool_constant("ODIN_NO_DYNAMIC_LITERALS",        bc->no_dynamic_literals);
 	add_global_bool_constant("ODIN_NO_CRT",                     bc->no_crt);
 	add_global_bool_constant("ODIN_USE_SEPARATE_MODULES",       bc->use_separate_modules);
 	add_global_bool_constant("ODIN_TEST",                       bc->command_kind == Command_test);
@@ -1356,6 +1372,7 @@ gb_internal void init_checker_info(CheckerInfo *i) {
 	mpsc_init(&i->required_global_variable_queue, a); // 1<<10);
 	mpsc_init(&i->required_foreign_imports_through_force_queue, a); // 1<<10);
 	mpsc_init(&i->foreign_imports_to_check_fullpaths, a); // 1<<10);
+	mpsc_init(&i->foreign_decls_to_check, a); // 1<<10);
 	mpsc_init(&i->intrinsics_entry_point_usage, a); // 1<<10); // just waste some memory here, even if it probably never used
 
 	string_map_init(&i->load_directory_cache);
@@ -1382,6 +1399,7 @@ gb_internal void destroy_checker_info(CheckerInfo *i) {
 	mpsc_destroy(&i->required_global_variable_queue);
 	mpsc_destroy(&i->required_foreign_imports_through_force_queue);
 	mpsc_destroy(&i->foreign_imports_to_check_fullpaths);
+	mpsc_destroy(&i->foreign_decls_to_check);
 
 	map_destroy(&i->objc_msgSend_types);
 	string_map_destroy(&i->load_file_cache);
@@ -5094,6 +5112,38 @@ gb_internal void check_foreign_import_fullpaths(Checker *c) {
 
 		e->LibraryName.paths = fl->fullpaths;
 	}
+
+	for (Entity *e = nullptr; mpsc_dequeue(&c->info.foreign_decls_to_check, &e); /**/) {
+		GB_ASSERT(e != nullptr);
+		if (e->kind != Entity_Procedure) {
+			continue;
+		}
+		if (!is_arch_wasm()) {
+			continue;
+		}
+		Entity *foreign_library = e->Procedure.foreign_library;
+		GB_ASSERT(foreign_library != nullptr);
+
+		String name = e->Procedure.link_name;
+
+		String module_name = str_lit("env");
+		GB_ASSERT (foreign_library->kind == Entity_LibraryName);
+		if (foreign_library->LibraryName.paths.count != 1) {
+			error(foreign_library->token, "'foreign import' for '%.*s' architecture may only have one path, got %td",
+			      LIT(target_arch_names[build_context.metrics.arch]), foreign_library->LibraryName.paths.count);
+		}
+
+		if (foreign_library->LibraryName.paths.count >= 1) {
+			module_name = foreign_library->LibraryName.paths[0];
+		}
+
+		if (!string_ends_with(module_name, str_lit(".o"))) {
+			name = concatenate3_strings(permanent_allocator(), module_name, WASM_MODULE_NAME_SEPARATOR, name);
+		}
+		e->Procedure.link_name = name;
+
+		check_foreign_procedure(&ctx, e, e->decl_info);
+	}
 }
 
 gb_internal void check_add_foreign_import_decl(CheckerContext *ctx, Ast *decl) {
diff --git a/src/checker.hpp b/src/checker.hpp
index 438156f18..3951fcefe 100644
--- a/src/checker.hpp
+++ b/src/checker.hpp
@@ -461,6 +461,7 @@ struct CheckerInfo {
 	MPSCQueue<Entity *> required_global_variable_queue;
 	MPSCQueue<Entity *> required_foreign_imports_through_force_queue;
 	MPSCQueue<Entity *> foreign_imports_to_check_fullpaths;
+	MPSCQueue<Entity *> foreign_decls_to_check;
 
 	MPSCQueue<Ast *> intrinsics_entry_point_usage;
 
@@ -521,6 +522,7 @@ struct CheckerContext {
 	bool       in_enum_type;
 	bool       collect_delayed_decls;
 	bool       allow_polymorphic_types;
+	bool       disallow_polymorphic_return_types; // NOTE(zen3ger): no poly type decl in return types
 	bool       no_polymorphic_errors;
 	bool       hide_polymorphic_errors;
 	bool       in_polymorphic_specialization;
diff --git a/src/entity.cpp b/src/entity.cpp
index 0c4a20df4..802b381f9 100644
--- a/src/entity.cpp
+++ b/src/entity.cpp
@@ -256,6 +256,7 @@ struct Entity {
 			bool    entry_point_only           : 1;
 			bool    has_instrumentation        : 1;
 			bool    is_memcpy_like             : 1;
+			bool    uses_branch_location       : 1;
 		} Procedure;
 		struct {
 			Array<Entity *> entities;
diff --git a/src/llvm_backend.cpp b/src/llvm_backend.cpp
index 01ded321e..696ced0df 100644
--- a/src/llvm_backend.cpp
+++ b/src/llvm_backend.cpp
@@ -1096,8 +1096,6 @@ gb_internal void lb_internal_dynamic_map_set(lbProcedure *p, lbValue const &map_
 }
 
 gb_internal lbValue lb_dynamic_map_reserve(lbProcedure *p, lbValue const &map_ptr, isize const capacity, TokenPos const &pos) {
-	GB_ASSERT(!build_context.no_dynamic_literals);
-
 	TEMPORARY_ALLOCATOR_GUARD();
 
 	String proc_name = {};
diff --git a/src/llvm_backend.hpp b/src/llvm_backend.hpp
index e84ffd1cd..42d283a1e 100644
--- a/src/llvm_backend.hpp
+++ b/src/llvm_backend.hpp
@@ -359,6 +359,10 @@ struct lbProcedure {
 	bool             in_multi_assignment;
 	Array<LLVMValueRef> raw_input_parameters;
 
+	bool             uses_branch_location;
+	TokenPos         branch_location_pos;
+	TokenPos         curr_token_pos;
+
 	Array<lbVariadicReuseSlices> variadic_reuses;
 	lbAddr variadic_reuse_base_array_ptr;
 
@@ -444,7 +448,8 @@ gb_internal lbValue lb_emit_matrix_ev(lbProcedure *p, lbValue s, isize row, isiz
 
 gb_internal lbValue lb_emit_arith(lbProcedure *p, TokenKind op, lbValue lhs, lbValue rhs, Type *type);
 gb_internal lbValue lb_emit_byte_swap(lbProcedure *p, lbValue value, Type *end_type);
-gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block);
+gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, TokenPos pos);
+gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, Ast *node);
 gb_internal lbValue lb_emit_transmute(lbProcedure *p, lbValue value, Type *t);
 gb_internal lbValue lb_emit_comp(lbProcedure *p, TokenKind op_kind, lbValue left, lbValue right);
 gb_internal lbValue lb_emit_call(lbProcedure *p, lbValue value, Array<lbValue> const &args, ProcInlining inlining = ProcInlining_none);
@@ -742,3 +747,5 @@ gb_global char const *llvm_linkage_strings[] = {
 };
 
 #define ODIN_METADATA_IS_PACKED str_lit("odin-is-packed")
+#define ODIN_METADATA_MIN_ALIGN str_lit("odin-min-align")
+#define ODIN_METADATA_MAX_ALIGN str_lit("odin-max-align")
diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index 9c325e088..df9dca801 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -3502,7 +3502,13 @@ gb_internal lbValue lb_build_expr_internal(lbProcedure *p, Ast *expr) {
 
 	case_ast_node(bd, BasicDirective, expr);
 		TokenPos pos = bd->token.pos;
-		GB_PANIC("Non-constant basic literal %s - %.*s", token_pos_to_string(pos), LIT(bd->name.string));
+		String name = bd->name.string;
+		if (name == "branch_location") {
+			GB_ASSERT(p->uses_branch_location);
+			String proc_name = p->entity->token.string;
+			return lb_emit_source_code_location_as_global(p, proc_name, p->branch_location_pos);
+		}
+		GB_PANIC("Non-constant basic literal %s - %.*s", token_pos_to_string(pos), LIT(name));
 	case_end;
 
 	case_ast_node(i, Implicit, expr);
@@ -3668,7 +3674,7 @@ gb_internal lbValue lb_build_expr_internal(lbProcedure *p, Ast *expr) {
 
 		lb_emit_if(p, lb_emit_try_has_value(p, rhs), then, else_);
 		lb_start_block(p, else_);
-		lb_emit_defer_stmts(p, lbDeferExit_Branch, block);
+		lb_emit_defer_stmts(p, lbDeferExit_Branch, block, expr);
 		lb_emit_jump(p, block);
 		lb_start_block(p, then);
 
@@ -4807,7 +4813,7 @@ gb_internal lbAddr lb_build_addr_compound_lit(lbProcedure *p, Ast *expr) {
 		if (cl->elems.count == 0) {
 			break;
 		}
-		GB_ASSERT(!build_context.no_dynamic_literals);
+		GB_ASSERT(expr->file()->feature_flags & OptInFeatureFlag_DynamicLiterals);
 
 		lbValue err = lb_dynamic_map_reserve(p, v.addr, 2*cl->elems.count, pos);
 		gb_unused(err);
@@ -4896,7 +4902,7 @@ gb_internal lbAddr lb_build_addr_compound_lit(lbProcedure *p, Ast *expr) {
 		if (cl->elems.count == 0) {
 			break;
 		}
-		GB_ASSERT(!build_context.no_dynamic_literals);
+		GB_ASSERT(expr->file()->feature_flags & OptInFeatureFlag_DynamicLiterals);
 
 		Type *et = bt->DynamicArray.elem;
 		lbValue size  = lb_const_int(p->module, t_int, type_size_of(et));
@@ -5493,7 +5499,7 @@ gb_internal lbAddr lb_build_addr_internal(lbProcedure *p, Ast *expr) {
 
 		lb_emit_if(p, lb_emit_try_has_value(p, rhs), then, else_);
 		lb_start_block(p, else_);
-		lb_emit_defer_stmts(p, lbDeferExit_Branch, block);
+		lb_emit_defer_stmts(p, lbDeferExit_Branch, block, expr);
 		lb_emit_jump(p, block);
 		lb_start_block(p, then);
 
diff --git a/src/llvm_backend_general.cpp b/src/llvm_backend_general.cpp
index bab330da7..762256258 100644
--- a/src/llvm_backend_general.cpp
+++ b/src/llvm_backend_general.cpp
@@ -734,6 +734,17 @@ gb_internal LLVMValueRef OdinLLVMBuildLoad(lbProcedure *p, LLVMTypeRef type, LLV
 		if (is_packed != 0) {
 			LLVMSetAlignment(result, 1);
 		}
+		u64 align = LLVMGetAlignment(result);
+		u64 align_min = lb_get_metadata_custom_u64(p->module, value, ODIN_METADATA_MIN_ALIGN);
+		u64 align_max = lb_get_metadata_custom_u64(p->module, value, ODIN_METADATA_MAX_ALIGN);
+		if (align_min != 0 && align < align_min) {
+			align = align_min;
+		}
+		if (align_max != 0 && align > align_max) {
+			align = align_max;
+		}
+		GB_ASSERT(align <= UINT_MAX);
+		LLVMSetAlignment(result, (unsigned int)align);
 	}
 
 	return result;
@@ -2121,6 +2132,7 @@ gb_internal LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 			}
 			
 			i64 prev_offset = 0;
+			bool requires_packing = type->Struct.is_packed;
 			for (i32 field_index : struct_fields_index_by_increasing_offset(temporary_allocator(), type)) {
 				Entity *field = type->Struct.fields[field_index];
 				i64 offset = type->Struct.offsets[field_index];
@@ -2141,6 +2153,10 @@ gb_internal LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 					field_type = t_rawptr;
 				}
 
+				// max_field_align might misalign items in a way that requires packing
+				// so check the alignment of all fields to see if packing is required.
+				requires_packing = requires_packing || ((offset % type_align_of(field_type)) != 0);
+
 				array_add(&fields, lb_type(m, field_type));
 
 				prev_offset = offset + type_size_of(field->type);
@@ -2155,7 +2171,7 @@ gb_internal LLVMTypeRef lb_type_internal(lbModule *m, Type *type) {
 				GB_ASSERT(fields[i] != nullptr);
 			}
 			
-			LLVMTypeRef struct_type = LLVMStructTypeInContext(ctx, fields.data, cast(unsigned)fields.count, type->Struct.is_packed);
+			LLVMTypeRef struct_type = LLVMStructTypeInContext(ctx, fields.data, cast(unsigned)fields.count, requires_packing);
 			map_set(&m->struct_field_remapping, cast(void *)struct_type, field_remapping);
 			map_set(&m->struct_field_remapping, cast(void *)type, field_remapping);			
 			#if 0
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index 712e13592..7e44a0046 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -125,6 +125,10 @@ gb_internal lbProcedure *lb_create_procedure(lbModule *m, Entity *entity, bool i
 	// map_init(&p->selector_addr,    0);
 	// map_init(&p->tuple_fix_map,    0);
 
+	if (p->entity != nullptr && p->entity->Procedure.uses_branch_location) {
+		p->uses_branch_location = true;
+	}
+
 	if (p->is_foreign) {
 		lb_add_foreign_library_path(p->module, entity->Procedure.foreign_library);
 	}
@@ -757,7 +761,7 @@ gb_internal void lb_end_procedure_body(lbProcedure *p) {
 	if (p->type->Proc.result_count == 0) {
 		instr = LLVMGetLastInstruction(p->curr_block->block);
 		if (!lb_is_instr_terminating(instr)) {
-			lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+			lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, p->body);
 			lb_set_debug_position_to_procedure_end(p);
 			LLVMBuildRetVoid(p->builder);
 		}
diff --git a/src/llvm_backend_stmt.cpp b/src/llvm_backend_stmt.cpp
index 9a5f25712..a2f0d2f4a 100644
--- a/src/llvm_backend_stmt.cpp
+++ b/src/llvm_backend_stmt.cpp
@@ -208,8 +208,8 @@ gb_internal void lb_open_scope(lbProcedure *p, Scope *s) {
 
 }
 
-gb_internal void lb_close_scope(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, bool pop_stack=true) {
-	lb_emit_defer_stmts(p, kind, block);
+gb_internal void lb_close_scope(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, Ast *node, bool pop_stack=true) {
+	lb_emit_defer_stmts(p, kind, block, node);
 	GB_ASSERT(p->scope_index > 0);
 
 	// NOTE(bill): Remove `context`s made in that scope
@@ -721,7 +721,7 @@ gb_internal void lb_build_range_interval(lbProcedure *p, AstBinaryExpr *node,
 
 		lb_build_stmt(p, rs->body);
 
-		lb_close_scope(p, lbDeferExit_Default, nullptr);
+		lb_close_scope(p, lbDeferExit_Default, nullptr, node->left);
 		lb_pop_target_list(p);
 
 		if (check != nullptr) {
@@ -854,7 +854,7 @@ gb_internal void lb_build_range_tuple(lbProcedure *p, AstRangeStmt *rs, Scope *s
 
 	lb_build_stmt(p, rs->body);
 
-	lb_close_scope(p, lbDeferExit_Default, nullptr);
+	lb_close_scope(p, lbDeferExit_Default, nullptr, rs->body);
 	lb_pop_target_list(p);
 	lb_emit_jump(p, loop);
 	lb_start_block(p, done);
@@ -976,7 +976,7 @@ gb_internal void lb_build_range_stmt_struct_soa(lbProcedure *p, AstRangeStmt *rs
 
 	lb_build_stmt(p, rs->body);
 
-	lb_close_scope(p, lbDeferExit_Default, nullptr);
+	lb_close_scope(p, lbDeferExit_Default, nullptr, rs->body);
 	lb_pop_target_list(p);
 	lb_emit_jump(p, loop);
 	lb_start_block(p, done);
@@ -1192,7 +1192,7 @@ gb_internal void lb_build_range_stmt(lbProcedure *p, AstRangeStmt *rs, Scope *sc
 
 	lb_build_stmt(p, rs->body);
 
-	lb_close_scope(p, lbDeferExit_Default, nullptr);
+	lb_close_scope(p, lbDeferExit_Default, nullptr, rs->body);
 	lb_pop_target_list(p);
 	lb_emit_jump(p, loop);
 	lb_start_block(p, done);
@@ -1363,7 +1363,7 @@ gb_internal void lb_build_unroll_range_stmt(lbProcedure *p, AstUnrollRangeStmt *
 	}
 
 
-	lb_close_scope(p, lbDeferExit_Default, nullptr);
+	lb_close_scope(p, lbDeferExit_Default, nullptr, rs->body);
 }
 
 gb_internal bool lb_switch_stmt_can_be_trivial_jump_table(AstSwitchStmt *ss, bool *default_found_) {
@@ -1433,6 +1433,7 @@ gb_internal void lb_build_switch_stmt(lbProcedure *p, AstSwitchStmt *ss, Scope *
 	ast_node(body, BlockStmt, ss->body);
 
 	isize case_count = body->stmts.count;
+	Ast *default_clause = nullptr;
 	Slice<Ast *> default_stmts = {};
 	lbBlock *default_fall = nullptr;
 	lbBlock *default_block = nullptr;
@@ -1482,6 +1483,7 @@ gb_internal void lb_build_switch_stmt(lbProcedure *p, AstSwitchStmt *ss, Scope *
 
 		if (cc->list.count == 0) {
 			// default case
+			default_clause = clause;
 			default_stmts = cc->stmts;
 			default_fall  = fall;
 			if (switch_instr == nullptr) {
@@ -1552,7 +1554,7 @@ gb_internal void lb_build_switch_stmt(lbProcedure *p, AstSwitchStmt *ss, Scope *
 		lb_push_target_list(p, ss->label, done, nullptr, fall);
 		lb_open_scope(p, body->scope);
 		lb_build_stmt_list(p, cc->stmts);
-		lb_close_scope(p, lbDeferExit_Default, body);
+		lb_close_scope(p, lbDeferExit_Default, body, clause);
 		lb_pop_target_list(p);
 
 		lb_emit_jump(p, done);
@@ -1570,13 +1572,13 @@ gb_internal void lb_build_switch_stmt(lbProcedure *p, AstSwitchStmt *ss, Scope *
 		lb_push_target_list(p, ss->label, done, nullptr, default_fall);
 		lb_open_scope(p, default_block->scope);
 		lb_build_stmt_list(p, default_stmts);
-		lb_close_scope(p, lbDeferExit_Default, default_block);
+		lb_close_scope(p, lbDeferExit_Default, default_block, default_clause);
 		lb_pop_target_list(p);
 	}
 
 	lb_emit_jump(p, done);
 	lb_start_block(p, done);
-	lb_close_scope(p, lbDeferExit_Default, done);
+	lb_close_scope(p, lbDeferExit_Default, done, ss->body);
 }
 
 gb_internal void lb_store_type_case_implicit(lbProcedure *p, Ast *clause, lbValue value, bool is_default_case) {
@@ -1627,7 +1629,7 @@ gb_internal void lb_type_case_body(lbProcedure *p, Ast *label, Ast *clause, lbBl
 
 	lb_push_target_list(p, label, done, nullptr, nullptr);
 	lb_build_stmt_list(p, cc->stmts);
-	lb_close_scope(p, lbDeferExit_Default, body);
+	lb_close_scope(p, lbDeferExit_Default, body, clause);
 	lb_pop_target_list(p);
 
 	lb_emit_jump(p, done);
@@ -1835,7 +1837,7 @@ gb_internal void lb_build_type_switch_stmt(lbProcedure *p, AstTypeSwitchStmt *ss
 
 	lb_emit_jump(p, done);
 	lb_start_block(p, done);
-	lb_close_scope(p, lbDeferExit_Default, done);
+	lb_close_scope(p, lbDeferExit_Default, done, ss->body);
 }
 
 
@@ -1959,7 +1961,7 @@ gb_internal void lb_build_assignment(lbProcedure *p, Array<lbAddr> &lvals, Slice
 	p->in_multi_assignment = prev_in_assignment;
 }
 
-gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res) {
+gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res, TokenPos pos) {
 	lbFunctionType *ft = lb_get_function_type(p->module, p->type);
 	bool return_by_pointer = ft->ret.kind == lbArg_Indirect;
 	bool split_returns = ft->multiple_return_original_type != nullptr;
@@ -1982,7 +1984,7 @@ gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res) {
 			LLVMBuildStore(p->builder, LLVMConstNull(p->abi_function_type->ret.type), p->return_ptr.addr.value);
 		}
 
-		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, pos);
 
 		// Check for terminator in the defer stmts
 		LLVMValueRef instr = LLVMGetLastInstruction(p->curr_block->block);
@@ -2012,7 +2014,7 @@ gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res) {
 			ret_val = OdinLLVMBuildTransmute(p, ret_val, ret_type);
 		}
 
-		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, pos);
 
 		// Check for terminator in the defer stmts
 		LLVMValueRef instr = LLVMGetLastInstruction(p->curr_block->block);
@@ -2021,7 +2023,7 @@ gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res) {
 		}
 	}
 }
-gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return_results) {
+gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return_results, TokenPos pos) {
 	lb_ensure_abi_function_type(p->module, p);
 
 	isize return_count = p->type->Proc.result_count;
@@ -2029,7 +2031,7 @@ gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return
 	if (return_count == 0) {
 		// No return values
 
-		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+		lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, pos);
 		
 		// Check for terminator in the defer stmts
 		LLVMValueRef instr = LLVMGetLastInstruction(p->curr_block->block);
@@ -2138,11 +2140,11 @@ gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return
 				GB_ASSERT(result_values.count-1 == result_eps.count);
 				lb_addr_store(p, p->return_ptr, result_values[result_values.count-1]);
 
-				lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+				lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, pos);
 				LLVMBuildRetVoid(p->builder);
 				return;
 			} else {
-				return lb_build_return_stmt_internal(p, result_values[result_values.count-1]);
+				return lb_build_return_stmt_internal(p, result_values[result_values.count-1], pos);
 			}
 
 		} else {
@@ -2169,7 +2171,7 @@ gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return
 			}
 
 			if (return_by_pointer) {
-				lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr);
+				lb_emit_defer_stmts(p, lbDeferExit_Return, nullptr, pos);
 				LLVMBuildRetVoid(p->builder);
 				return;
 			}
@@ -2177,13 +2179,13 @@ gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return
 			res = lb_emit_load(p, res);
 		}
 	}
-	lb_build_return_stmt_internal(p, res);
+	lb_build_return_stmt_internal(p, res, pos);
 }
 
 gb_internal void lb_build_if_stmt(lbProcedure *p, Ast *node) {
 	ast_node(is, IfStmt, node);
 	lb_open_scope(p, is->scope); // Scope #1
-	defer (lb_close_scope(p, lbDeferExit_Default, nullptr));
+	defer (lb_close_scope(p, lbDeferExit_Default, nullptr, node));
 
 	lbBlock *then = lb_create_block(p, "if.then");
 	lbBlock *done = lb_create_block(p, "if.done");
@@ -2234,7 +2236,7 @@ gb_internal void lb_build_if_stmt(lbProcedure *p, Ast *node) {
 
 				lb_open_scope(p, scope_of_node(is->else_stmt));
 				lb_build_stmt(p, is->else_stmt);
-				lb_close_scope(p, lbDeferExit_Default, nullptr);
+				lb_close_scope(p, lbDeferExit_Default, nullptr, is->else_stmt);
 			}
 			lb_emit_jump(p, done);
 
@@ -2251,7 +2253,7 @@ gb_internal void lb_build_if_stmt(lbProcedure *p, Ast *node) {
 
 			lb_open_scope(p, scope_of_node(is->else_stmt));
 			lb_build_stmt(p, is->else_stmt);
-			lb_close_scope(p, lbDeferExit_Default, nullptr);
+			lb_close_scope(p, lbDeferExit_Default, nullptr, is->else_stmt);
 
 			lb_emit_jump(p, done);
 		}
@@ -2322,7 +2324,7 @@ gb_internal void lb_build_for_stmt(lbProcedure *p, Ast *node) {
 	}
 
 	lb_start_block(p, done);
-	lb_close_scope(p, lbDeferExit_Default, nullptr);
+	lb_close_scope(p, lbDeferExit_Default, nullptr, node);
 }
 
 gb_internal void lb_build_assign_stmt_array(lbProcedure *p, TokenKind op, lbAddr const &lhs, lbValue const &value) {
@@ -2588,7 +2590,7 @@ gb_internal void lb_build_stmt(lbProcedure *p, Ast *node) {
 
 		lb_open_scope(p, bs->scope);
 		lb_build_stmt_list(p, bs->stmts);
-		lb_close_scope(p, lbDeferExit_Default, nullptr);
+		lb_close_scope(p, lbDeferExit_Default, nullptr, node);
 
 		if (done != nullptr) {
 			lb_emit_jump(p, done);
@@ -2702,7 +2704,7 @@ gb_internal void lb_build_stmt(lbProcedure *p, Ast *node) {
 	case_end;
 
 	case_ast_node(rs, ReturnStmt, node);
-		lb_build_return_stmt(p, rs->results);
+		lb_build_return_stmt(p, rs->results, ast_token(node).pos);
 	case_end;
 
 	case_ast_node(is, IfStmt, node);
@@ -2755,7 +2757,7 @@ gb_internal void lb_build_stmt(lbProcedure *p, Ast *node) {
 			}
 		}
 		if (block != nullptr) {
-			lb_emit_defer_stmts(p, lbDeferExit_Branch, block);
+			lb_emit_defer_stmts(p, lbDeferExit_Branch, block, node);
 		}
 		lb_emit_jump(p, block);
 		lb_start_block(p, lb_create_block(p, "unreachable"));
@@ -2795,7 +2797,13 @@ gb_internal void lb_build_defer_stmt(lbProcedure *p, lbDefer const &d) {
 	}
 }
 
-gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block) {
+gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, TokenPos pos) {
+	TokenPos prev_token_pos = p->branch_location_pos;
+	if (p->uses_branch_location) {
+		p->branch_location_pos = pos;
+	}
+	defer (p->branch_location_pos = prev_token_pos);
+
 	isize count = p->defer_stmts.count;
 	isize i = count;
 	while (i --> 0) {
@@ -2822,6 +2830,21 @@ gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlo
 	}
 }
 
+gb_internal void lb_emit_defer_stmts(lbProcedure *p, lbDeferExitKind kind, lbBlock *block, Ast *node) {
+	TokenPos pos = {};
+	if (node) {
+		if (node->kind == Ast_BlockStmt) {
+			pos = ast_end_token(node).pos;
+		} else if (node->kind == Ast_CaseClause) {
+			pos = ast_end_token(node).pos;
+		} else {
+			pos = ast_token(node).pos;
+		}
+	}
+	return lb_emit_defer_stmts(p, kind, block, pos);
+}
+
+
 gb_internal void lb_add_defer_node(lbProcedure *p, isize scope_index, Ast *stmt) {
 	Type *pt = base_type(p->type);
 	GB_ASSERT(pt->kind == Type_Proc);
diff --git a/src/llvm_backend_utility.cpp b/src/llvm_backend_utility.cpp
index a2a0ba4cc..7b7c9d6e9 100644
--- a/src/llvm_backend_utility.cpp
+++ b/src/llvm_backend_utility.cpp
@@ -476,8 +476,8 @@ gb_internal lbValue lb_emit_or_else(lbProcedure *p, Ast *arg, Ast *else_expr, Ty
 	}
 }
 
-gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return_results);
-gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res);
+gb_internal void lb_build_return_stmt(lbProcedure *p, Slice<Ast *> const &return_results, TokenPos pos);
+gb_internal void lb_build_return_stmt_internal(lbProcedure *p, lbValue res, TokenPos pos);
 
 gb_internal lbValue lb_emit_or_return(lbProcedure *p, Ast *arg, TypeAndValue const &tv) {
 	lbValue lhs = {};
@@ -506,10 +506,10 @@ gb_internal lbValue lb_emit_or_return(lbProcedure *p, Ast *arg, TypeAndValue con
 			lbValue found = map_must_get(&p->module->values, end_entity);
 			lb_emit_store(p, found, rhs);
 
-			lb_build_return_stmt(p, {});
+			lb_build_return_stmt(p, {}, ast_token(arg).pos);
 		} else {
 			GB_ASSERT(tuple->variables.count == 1);
-			lb_build_return_stmt_internal(p, rhs);
+			lb_build_return_stmt_internal(p, rhs, ast_token(arg).pos);
 		}
 	}
 	lb_start_block(p, continue_block);
@@ -1200,9 +1200,22 @@ gb_internal lbValue lb_emit_struct_ep(lbProcedure *p, lbValue s, i32 index) {
 	lbValue gep = lb_emit_struct_ep_internal(p, s, index, result_type);
 
 	Type *bt = base_type(t);
-	if (bt->kind == Type_Struct && bt->Struct.is_packed) {
-		lb_set_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_IS_PACKED, 1);
-		GB_ASSERT(lb_get_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_IS_PACKED) == 1);
+	if (bt->kind == Type_Struct) {
+		if (bt->Struct.is_packed) {
+			lb_set_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_IS_PACKED, 1);
+			GB_ASSERT(lb_get_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_IS_PACKED) == 1);
+		}
+		u64 align_max = bt->Struct.custom_max_field_align;
+		u64 align_min = bt->Struct.custom_min_field_align;
+		GB_ASSERT(align_min == 0 || align_max == 0 || align_min <= align_max);
+		if (align_max) {
+			lb_set_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_MAX_ALIGN, align_max);
+			GB_ASSERT(lb_get_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_MAX_ALIGN) == align_max);
+		}
+		if (align_min) {
+			lb_set_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_MIN_ALIGN, align_min);
+			GB_ASSERT(lb_get_metadata_custom_u64(p->module, gep.value, ODIN_METADATA_MIN_ALIGN) == align_min);
+		}
 	}
 
 	return gep;
diff --git a/src/main.cpp b/src/main.cpp
index 4d85a9e72..41c7170f6 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1192,7 +1192,7 @@ gb_internal bool parse_build_flags(Array<String> args) {
 							build_context.no_type_assert = true;
 							break;
 						case BuildFlag_NoDynamicLiterals:
-							build_context.no_dynamic_literals = true;
+							gb_printf_err("Warning: Use of -no-dynamic-literals is now redundant\n");
 							break;
 						case BuildFlag_NoCRT:
 							build_context.no_crt = true;
@@ -2120,7 +2120,7 @@ gb_internal void export_dependencies(Checker *c) {
 		for_array(i, files) {
 			AstFile *file = files[i];
 			gb_fprintf(&f, "\t\t\"%.*s\"", LIT(file->fullpath));
-			if (i+1 == files.count) {
+			if (i+1 < files.count) {
 				gb_fprintf(&f, ",");
 			}
 			gb_fprintf(&f, "\n");
@@ -2133,7 +2133,7 @@ gb_internal void export_dependencies(Checker *c) {
 		for_array(i, load_files) {
 			LoadFileCache *cache = load_files[i];
 			gb_fprintf(&f, "\t\t\"%.*s\"", LIT(cache->path));
-			if (i+1 == load_files.count) {
+			if (i+1 < load_files.count) {
 				gb_fprintf(&f, ",");
 			}
 			gb_fprintf(&f, "\n");
diff --git a/src/parser.cpp b/src/parser.cpp
index aa90651d3..03c5a5962 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -6265,10 +6265,16 @@ gb_internal u64 parse_vet_tag(Token token_for_pos, String s) {
 			syntax_error(token_for_pos, "Invalid vet flag name: %.*s", LIT(p));
 			error_line("\tExpected one of the following\n");
 			error_line("\tunused\n");
+			error_line("\tunused-variables\n");
+			error_line("\tunused-imports\n");
+			error_line("\tunused-procedures\n");
 			error_line("\tshadowing\n");
 			error_line("\tusing-stmt\n");
 			error_line("\tusing-param\n");
+			error_line("\tstyle\n");
 			error_line("\textra\n");
+			error_line("\tcast\n");
+			error_line("\ttabs\n");
 			return build_context.vet_flags;
 		}
 	}
@@ -6286,6 +6292,63 @@ gb_internal u64 parse_vet_tag(Token token_for_pos, String s) {
 	return vet_flags &~ vet_not_flags;
 }
 
+gb_internal u64 parse_feature_tag(Token token_for_pos, String s) {
+	String const prefix = str_lit("feature");
+	GB_ASSERT(string_starts_with(s, prefix));
+	s = string_trim_whitespace(substring(s, prefix.len, s.len));
+
+	if (s.len == 0) {
+		return OptInFeatureFlag_NONE;
+	}
+
+	u64 feature_flags = 0;
+	u64 feature_not_flags = 0;
+
+	while (s.len > 0) {
+		String p = string_trim_whitespace(vet_tag_get_token(s, &s));
+		if (p.len == 0) {
+			break;
+		}
+
+		bool is_notted = false;
+		if (p[0] == '!') {
+			is_notted = true;
+			p = substring(p, 1, p.len);
+			if (p.len == 0) {
+				syntax_error(token_for_pos, "Expected a feature flag name after '!'");
+				return OptInFeatureFlag_NONE;
+			}
+		}
+
+		u64 flag = get_feature_flag_from_name(p);
+		if (flag != OptInFeatureFlag_NONE) {
+			if (is_notted) {
+				feature_not_flags |= flag;
+			} else {
+				feature_flags     |= flag;
+			}
+		} else {
+			ERROR_BLOCK();
+			syntax_error(token_for_pos, "Invalid feature flag name: %.*s", LIT(p));
+			error_line("\tExpected one of the following\n");
+			error_line("\tdynamic-literals\n");
+			return OptInFeatureFlag_NONE;
+		}
+	}
+
+	if (feature_flags == 0 && feature_not_flags == 0) {
+		return OptInFeatureFlag_NONE;
+	}
+	if (feature_flags == 0 && feature_not_flags != 0) {
+		return OptInFeatureFlag_NONE &~ feature_not_flags;
+	}
+	if (feature_flags != 0 && feature_not_flags == 0) {
+		return feature_flags;
+	}
+	GB_ASSERT(feature_flags != 0 && feature_not_flags != 0);
+	return feature_flags &~ feature_not_flags;
+}
+
 gb_internal String dir_from_path(String path) {
 	String base_dir = path;
 	for (isize i = path.len-1; i >= 0; i--) {
@@ -6399,6 +6462,9 @@ gb_internal bool parse_file_tag(const String &lc, const Token &tok, AstFile *f)
 		} else if (command == "file") {
 			f->flags |= AstFile_IsPrivateFile;
 		}
+	} else if (string_starts_with(lc, str_lit("feature"))) {
+		f->feature_flags |= parse_feature_tag(tok, lc);
+		f->feature_flags_set = true;
 	} else if (lc == "lazy") {
 		if (build_context.ignore_lazy) {
 			// Ignore
@@ -6493,9 +6559,7 @@ gb_internal bool parse_file(Parser *p, AstFile *f) {
 	}
 	f->package_name = package_name.string;
 
-	// TODO: Shouldn't single file only matter for build tags? no-instrumentation for example
-	// should be respected even when in single file mode.
-	if (!f->pkg->is_single_file) {
+	{
 		if (docs != nullptr && docs->list.count > 0) {
 			for (Token const &tok : docs->list) {
 				GB_ASSERT(tok.kind == Token_Comment);
diff --git a/src/parser.hpp b/src/parser.hpp
index e332fed50..bbf70d03e 100644
--- a/src/parser.hpp
+++ b/src/parser.hpp
@@ -108,7 +108,9 @@ struct AstFile {
 	String       package_name;
 
 	u64          vet_flags;
+	u64          feature_flags;
 	bool         vet_flags_set;
+	bool         feature_flags_set;
 
 	// >= 0: In Expression
 	// <  0: In Control Clause