build: host-only builtins move to one whole-TU-gated builtins_host.c (#741)

CHANGELOG.md

@@ -46,6 +46,31 @@ All notable changes to EigenScript are documented here.
 
 ### Changed
 
+- **Host-only builtins moved to one whole-TU-gated file,
+  `src/builtins_host.c` (#741).** `EIGENSCRIPT_FREESTANDING` was carved
+  into `builtins.c` inline — 52 `#ifdef` blocks gating ~1,500 lines, with
+  host-only builtins interleaved among portable ones, so the only feedback
+  that a new builtin had leaked a host dependency was the freestanding
+  symbol gate failing on a stray libc import. Everything needing a real OS
+  underneath — filesystem (`read_text`/`write_bytes`/`ls`/… and the module
+  resolver's host arm), subprocess (`exec_capture`, the `proc_*` family),
+  terminal raw mode, POSIX regex (`match`/`match_all`/`regex_replace`),
+  streams, `random_hex`, `build_corpus`, `read_file_util` — now lives in
+  `builtins_host.c` behind a single `#if` (the `ext_store.c` pattern:
+  under the profile the TU compiles to a no-op `register_host_builtins`
+  plus the resolver stub). `builtins.c` keeps 5 conditional sites, all
+  genuine dual-behavior carve-outs (glibc allocator introspection, the
+  `getpid` seed term, `try_parse`'s stderr fd-plumbing), and its
+  registration table calls the host registrar unconditionally inside the
+  `[0, g_builtin_binding_count)` builtin band. Zero behavior change under
+  the host profile; the freestanding surface is byte-identical (both
+  `freestanding_check.sh` stages pass unchanged, allowlist untouched). A
+  builtin that quietly grows a host dependency now fails the symbol gate
+  by NAME (`builtin_foo` undefined in the profile) instead of by stray
+  import, and the fix is structural — define it in the host TU. The
+  matching extraction for `lint.c`'s 6 blocks (the E003 binding base,
+  `--api`, `check_undefined_names`) is tracked separately.
+
 - **Build variants now coexist: per-variant objdirs with dependency
   tracking (#740).** Every runtime variant (`build`/`full`/`http`/`zlib`/
   `net`/`gfx`/`asan`/`asan-http`/`tsan`/`valgrind`/`poison`) was a single

Makefile

@@ -19,7 +19,7 @@ LDFLAGS := -pie -Wl,-z,relro,-z,now -lm -lpthread
 endif
 
 SRC_DIR := src
-SOURCES := $(SRC_DIR)/eigenscript.c $(SRC_DIR)/lexer.c $(SRC_DIR)/parser.c $(SRC_DIR)/builtins.c $(SRC_DIR)/builtins_tensor.c $(SRC_DIR)/hash.c $(SRC_DIR)/arena.c $(SRC_DIR)/state.c $(SRC_DIR)/strbuf.c $(SRC_DIR)/ext_store.c $(SRC_DIR)/fmt.c $(SRC_DIR)/lint.c $(SRC_DIR)/chunk.c $(SRC_DIR)/compiler.c $(SRC_DIR)/vm.c $(SRC_DIR)/jit.c $(SRC_DIR)/trace.c $(SRC_DIR)/eigs_embed.c $(SRC_DIR)/repl.c $(SRC_DIR)/step.c $(SRC_DIR)/tape_read.c $(SRC_DIR)/bundle.c $(SRC_DIR)/main.c
+SOURCES := $(SRC_DIR)/eigenscript.c $(SRC_DIR)/lexer.c $(SRC_DIR)/parser.c $(SRC_DIR)/builtins.c $(SRC_DIR)/builtins_host.c $(SRC_DIR)/builtins_tensor.c $(SRC_DIR)/hash.c $(SRC_DIR)/arena.c $(SRC_DIR)/state.c $(SRC_DIR)/strbuf.c $(SRC_DIR)/ext_store.c $(SRC_DIR)/fmt.c $(SRC_DIR)/lint.c $(SRC_DIR)/chunk.c $(SRC_DIR)/compiler.c $(SRC_DIR)/vm.c $(SRC_DIR)/jit.c $(SRC_DIR)/trace.c $(SRC_DIR)/eigs_embed.c $(SRC_DIR)/repl.c $(SRC_DIR)/step.c $(SRC_DIR)/tape_read.c $(SRC_DIR)/bundle.c $(SRC_DIR)/main.c
 BINARY  := $(SRC_DIR)/eigenscript
 
 # CLI-only translation units: linked into the binary, never into the

docs/FREESTANDING.md

@@ -199,7 +199,12 @@ DROP rows above name: the filesystem builtins (incl. `load_file`/`import`,
 which raise a profile-specific error), subprocess, terminal raw mode, libc
 regex (route: EigenRegex's `regex_compat`), the page store, the trace-tape
 file sinks, and the JIT (`EIGS_JIT_ENABLED` gates every arch check;
-interpreter-only until the `map_exec` root exists). The entry point is
+interpreter-only until the `map_exec` root exists). The host-only builtins
+live in one whole-TU-gated file, `src/builtins_host.c` (#741, the
+`ext_store.c` pattern — under the profile it compiles to a no-op registrar
+plus the resolver stub), so the drop is a single gate rather than ~50
+scattered `#ifdef` pairs, and a builtin that grows a host dependency
+belongs there by construction. The entry point is
 `eigs_embed.h` with **source strings** — `main.c` (the POSIX CLI) is not part
 of the profile.