ref: vendor harec checker sources (#20)

ref/hare/ ships only ast/lex/parse/module/unparse — no checker. Every
bail-fix landing in A.6.2.1 (helper bail audit, N_IDENT bail audit,
enum fold) needs a `ref/harec/...` cite anchor so divergence rationale
isn't claimed against memory. PLAN.md L16, L35.

Snapshot of upstream commit ee640c6b2c17f57e8014d277a3028b262ffb7952
(`rt/+openbsd/start.ha: remove outdated comment about crt0`). 20 files:
5 src (check.c, eval.c, scope.c, types.c, type_store.c), 14 transitive
include/ headers (no parser/codegen surface), and COPYING.

License GPLv3 (COPYING included). Vendored as read-only reference per
CLAUDE.md rule 6 — no redistribution as binary, no edits.

ref/harec/include/check.h

@@ -0,0 +1,169 @@
+#ifndef HARE_CHECK_H
+#define HARE_CHECK_H
+#include <stdbool.h>
+#include <stdnoreturn.h>
+#include "ast.h"
+#include "identifier.h"
+#include "scope.h"
+#include "types.h"
+#include "type_store.h"
+#include "util.h"
+
+struct expression;
+
+#define MODCACHE_BUCKETS 256
+
+struct modcache {
+	struct ident *ident;
+	struct scope *scope;
+	struct modcache *next;
+};
+
+struct errors {
+	struct location loc;
+	char *msg;
+	struct errors *next;
+};
+
+struct context {
+	type_store *store;
+	struct modcache **modcache;
+	const struct type *fntype;
+	struct ident *ns;
+	struct scope *unit;
+	struct scope *scope;
+	struct scope *defines;
+	const char *mainsym;
+	struct ident *mainident;
+	bool is_test;
+	int id;
+	struct errors *errors;
+	struct errors **next;
+	struct declarations *decls;
+	struct ast_types *unresolved;
+	struct intern_table *itbl;
+};
+
+struct constant_decl {
+	const struct type *type;
+	const struct expression *value;
+};
+
+struct function_decl {
+	const struct type *type;
+	struct expression *body;
+	struct scope *scope;
+	unsigned int flags; // enum func_decl_flags
+};
+
+struct global_decl {
+	const struct type *type;
+	struct expression *value; // EXPR_LITERAL
+	bool threadlocal;
+};
+
+enum decl_type {
+	DECL_FUNC,
+	DECL_TYPE,
+	DECL_GLOBAL,
+	DECL_CONST,
+};
+
+struct declaration {
+	enum decl_type decl_type;
+	int file;
+	struct ident *ident;
+	const char *symbol;
+	bool exported; // XXX: this bool takes up 8 bytes and i am in pain
+	union {
+		struct constant_decl constant;
+		struct function_decl func;
+		struct global_decl global;
+		const struct type *type;
+	};
+};
+
+struct declarations {
+	struct declaration decl;
+	struct declarations *next;
+};
+
+struct unit {
+	struct ident *ns;
+	struct declarations *declarations;
+	struct identifiers *imports;
+};
+
+enum idecl_type {
+	IDECL_DECL,
+	IDECL_ENUM_FLD,
+};
+
+// Keeps track of enum specific context required for enum field resolution
+struct incomplete_enum_field {
+	struct ast_enum_field *field;
+	struct scope *enum_scope;
+};
+
+// Keeps track of context required to resolve a declaration or an enum field
+// Extends the scope_object struct so it can be inserted into a scope
+struct incomplete_decl {
+	struct scope *imports; // the scope of this declaration's subunit
+	enum idecl_type type;
+	bool in_progress;
+	bool dealias_in_progress;
+	union {
+		struct ast_decl decl;
+		struct incomplete_enum_field *field;
+	};
+};
+
+struct ident *mkident(struct context *ctx, struct ident *ident,
+		const char *symbol);
+
+void append_decl(struct context *ctx, struct declaration *decl);
+
+void mkstrliteral(struct expression *expr, const char *fmt, ...) FORMAT(2, 3);
+
+char *gen_typename(const struct type *type);
+
+struct expression *lower_implicit_cast(struct context *ctx,
+		const struct type *to, struct expression *expr);
+
+typedef void (*resolvefn)(struct context *, struct scope_object *obj);
+
+void resolve_dimensions(struct context *ctx, struct scope_object *obj);
+
+void resolve_type(struct context *ctx, struct scope_object *obj);
+
+void wrap_resolver(struct context *ctx,
+	struct scope_object *obj, resolvefn resolver);
+
+struct scope *check(type_store *ts,
+	bool is_test,
+	const char *mainsym,
+	struct ident *mainident,
+	const struct ast_decls *defines,
+	const struct ast_unit *aunit,
+	struct unit *unit,
+	struct intern_table *itbl);
+
+struct scope *check_internal(type_store *ts,
+	struct modcache **cache,
+	bool is_test,
+	const char *mainsym,
+	struct ident *mainident,
+	const struct ast_decls *defines,
+	const struct ast_unit *aunit,
+	struct unit *unit,
+	struct intern_table *itbl,
+	bool scan_only);
+
+void check_expression(struct context *ctx,
+	const struct ast_expression *aexpr,
+	struct expression *expr,
+	const struct type *hint);
+
+void error(struct context *ctx, struct location loc,
+	struct expression *expr, const char *fmt, ...) FORMAT(4, 5);
+#endif