Replace CPPO browser branches with platform modules

AGENTS.md

@@ -72,6 +72,15 @@ JS IR
 JavaScript Code
 ```
 
+### Platform-specific compiler modules
+
+The Dune `browser` profile builds the playground compiler. Platform-dependent
+modules are stored below `platform/native/` and `platform/playground/` in their
+owning compiler directory. Rules in that directory's `dune` file copy the
+selected implementation into the build directory as an ordinary `.ml` module;
+all other profiles select the native source. Generated module paths in errors
+or stack traces therefore map back to one of those two source directories.
+
 ### Key Directory Structure
 
 ```

CHANGELOG.md

@@ -35,6 +35,7 @@
 
 - Add the `-check-lam` compiler option, enable Lambda invariant checking in compiler tests, and remove build-profile-dependent checking. https://github.com/rescript-lang/rescript/pull/8534
 - Replace `-bs-diagnose` with `-debug-ir` and make IR diagnostic artifacts deterministic, compilation-local, and easy to clean. https://github.com/rescript-lang/rescript/pull/8535
+- Replace CPPO-based browser conditionals with Dune-selected native and playground compiler implementations. https://github.com/rescript-lang/rescript/pull/8541
 
 # 13.0.0-alpha.5
 

CONTRIBUTING.md

@@ -297,6 +297,20 @@ The "Playground bundle" is a JS version of the ReScript compiler; including all
 
 The ReScript source code is compiled with a tool called [JSOO (js_of_ocaml)](https://ocsigen.org/js_of_ocaml/latest/manual/overview), which uses OCaml bytecode to compile to JavaScript and is part of the bigger OCaml ecosystem.
 
+### Platform-specific compiler modules
+
+Within `compiler/`, the Dune `browser` profile specifically means the
+playground compiler. A few modules have implementations under
+`platform/native/` and `platform/playground/`; mutually exclusive rules in the
+owning `dune` file copy the appropriate implementation into the build directory
+as an ordinary `.ml` module. Other profiles select the native implementation.
+
+Consequently, a generated filename such as `ext_platform_primitives.ml` may
+appear in a compiler stack trace even though it is not present in the source
+tree. Its source is the corresponding file below `platform/native/` or
+`platform/playground/` in the same compiler directory. Keep both
+implementations API-compatible when changing one of these modules.
+
 ### Building the Bundle
 
 The entry point of the JSOO bundle is located in `compiler/jsoo/jsoo_playground_main.ml`, the compiler and its relevant runtime cmij files can be built via make:
@@ -310,9 +324,9 @@ Note that building the cmijs is based on the dependencies defined in `packages/p
 
 After a successful compilation, you will find following files in your project:
 
-- `playground/compiler.js` -> This is the ReScript compiler, which binds the ReScript API to the `window` object.
-- `playground/packages/compiler-builtins` -> The compiler base cmij containing all the relevant core modules (`Js`, `Belt`, `Pervasives`, etc.)
-- `playground/packages/*` -> Contains third party deps with cmij.js files (as defined in `packages/playground/rescript.json`)
+- `packages/playground/compiler.js` -> This is the ReScript compiler, which binds the ReScript API to the `window` object.
+- `packages/playground/packages/compiler-builtins` -> The compiler base cmij containing all the relevant core modules (`Js`, `Belt`, `Pervasives`, etc.)
+- `packages/playground/packages/*` -> Contains third party deps with cmij.js files (as defined in `packages/playground/rescript.json`)
 
 You can now use the `compiler.js` file either directly by using a `<script src="/path/to/compiler.js"/>` and `<script src="/path/to/packages/compilerCmij.js"/>` inside a html file, use a browser bundler infrastructure to optimize it, or use `nodejs` to run it on a command line:
 

compiler/core/build_artifact_stubs.c

@@ -0,0 +1,33 @@
+#include "caml/memory.h"
+#include "caml/mlvalues.h"
+#include "caml/osdeps.h"
+#include "caml/signals.h"
+
+#ifdef _WIN32
+#include <sys/utime.h>
+
+CAMLprim value caml_stale_file(value path)
+{
+  CAMLparam1(path);
+  struct _utimbuf times;
+  char *os_path = caml_stat_strdup(String_val(path));
+  times.modtime = 0;
+  caml_enter_blocking_section();
+  _utime(os_path, &times);
+  caml_leave_blocking_section();
+  caml_stat_free(os_path);
+  CAMLreturn(Val_unit);
+}
+#else
+#include <sys/time.h>
+
+CAMLprim value caml_stale_file(value path)
+{
+  CAMLparam1(path);
+  struct timeval times[2] = {{0, 0}, {0, 0}};
+  char *os_path = caml_stat_strdup_to_os(String_val(path));
+  utimes(os_path, times);
+  caml_stat_free(os_path);
+  CAMLreturn(Val_unit);
+}
+#endif

compiler/core/dune

@@ -1,20 +1,44 @@
-(library
- (name core)
- (wrapped false)
- (instrumentation
-  (backend bisect_ppx))
- (flags
-  (:standard -w +a-4-9-27-30-40-41-42-48-70))
- (libraries depends ext flow_parser frontend gentype yojson))
+(env
+ (_
+  (flags
+   (:standard -w +a-4-9-27-30-40-41-42-48-70))))
+
+; The browser profile builds the playground compiler; these rules generate modules from platform/{native,playground}.
+
+(rule
+ (target build_artifact.ml)
+ (enabled_if
+  (= %{profile} browser))
+ (action
+  (copy platform/playground/build_artifact.ml build_artifact.ml)))
+
+(rule
+ (target build_artifact.ml)
+ (enabled_if
+  (<> %{profile} browser))
+ (action
+  (copy platform/native/build_artifact.ml build_artifact.ml)))
 
 (rule
  (target js_name_of_module_id.ml)
- (deps js_name_of_module_id.cppo.ml)
+ (enabled_if
+  (= %{profile} browser))
  (action
-  (run %{bin:cppo} %{env:CPPO_FLAGS=} %{deps} -o %{target})))
+  (copy platform/playground/js_name_of_module_id.ml js_name_of_module_id.ml)))
 
 (rule
- (target lam_compile_main.ml)
- (deps lam_compile_main.cppo.ml)
+ (target js_name_of_module_id.ml)
+ (enabled_if
+  (<> %{profile} browser))
  (action
-  (run %{bin:cppo} %{env:CPPO_FLAGS=} %{deps} -o %{target})))
+  (copy platform/native/js_name_of_module_id.ml js_name_of_module_id.ml)))
+
+(library
+ (name core)
+ (wrapped false)
+ (instrumentation
+  (backend bisect_ppx))
+ (foreign_stubs
+  (language c)
+  (names build_artifact_stubs))
+ (libraries depends ext flow_parser frontend gentype yojson))