gh-126691: Remove --with-emscripten-target (#126787)

This unifies the code for nodejs and the code for the browser. After this
commit, the browser example doesn't work; this will be fixed in a
subsequent update.

Author: hoodmane

Doc/using/configure.rst

@@ -454,15 +454,6 @@ Options for third-party dependencies
 WebAssembly Options
 -------------------
 
-.. option:: --with-emscripten-target=[browser|node]
-
-   Set build flavor for ``wasm32-emscripten``.
-
-   * ``browser`` (default): preload minimal stdlib, default MEMFS.
-   * ``node``: NODERAWFS and pthread support.
-
-   .. versionadded:: 3.11
-
 .. option:: --enable-wasm-dynamic-linking
 
    Turn on dynamic linking support for WASM.

Misc/NEWS.d/next/Build/2024-11-13-15-47-09.gh-issue-126691.ni4K-b.rst

@@ -0,0 +1,3 @@
+Removed the ``--with-emscripten-target`` configure flag. We unified the
+``node`` and ``browser`` options and the same build can now be used, independent
+of target runtime.

Tools/wasm/README.md

@@ -21,12 +21,6 @@ https://github.com/psf/webassembly for more information.
 
 ### Build
 
-For now the build system has two target flavors. The ``Emscripten/browser``
-target (``--with-emscripten-target=browser``) is optimized for browsers.
-It comes with a reduced and preloaded stdlib without tests and threading
-support. The ``Emscripten/node`` target has threading enabled and can
-access the file system directly.
-
 To cross compile to the ``wasm32-emscripten`` platform you need
 [the Emscripten compiler toolchain](https://emscripten.org/), 
 a Python interpreter, and an installation of Node version 18 or newer. Emscripten

Tools/wasm/emscripten/node_pre.js

@@ -1,9 +1,15 @@
 // If process is undefined, we're not running in the node runtime let it go I
 // guess?
 if (typeof process !== "undefined") {
-    const nodeVersion = Number(process.versions.node.split('.',1)[0]);
+    const nodeVersion = Number(process.versions.node.split(".", 1)[0]);
     if (nodeVersion < 18) {
-        process.stderr.write(`Node version must be >= 18, got version ${process.version}\n`);
+        process.stderr.write(
+            `Node version must be >= 18, got version ${process.version}\n`,
+        );
         process.exit(1);
     }
+    Module.preRun = () => {
+        FS.mkdirTree("/lib/");
+        FS.mount(NODEFS, { root: __dirname + "/lib/" }, "/lib/");
+    };
 }

configure

@@ -1282,30 +1282,6 @@ AS_CASE([$ac_sys_system/$ac_sys_release],
  ]
 )
 
-AC_MSG_CHECKING([for --with-emscripten-target])
-AC_ARG_WITH([emscripten-target],
-  [AS_HELP_STRING([--with-emscripten-target=@<:@browser|node@:>@], [Emscripten platform])],
-[
-	AS_VAR_IF([ac_sys_system], [Emscripten], [
-    AS_CASE([$with_emscripten_target],
-      [browser], [ac_sys_emscripten_target=browser],
-      [node], [ac_sys_emscripten_target=node],
-dnl Debug builds with source map / dwarf symbols. Py_DEBUG builds easily
-dnl run out of stack space. Detached sybmols and map prohibit some
-dnl optimizations and increase file size. Options are undocumented so we
-dnl are free to remove them in the future.
-      [browser-debug], [ac_sys_emscripten_target=browser-debug],
-      [node-debug], [ac_sys_emscripten_target=node-debug],
-      [AC_MSG_ERROR([Invalid argument: --with-emscripten-target=browser|node])]
-    )
-  ], [
-    AC_MSG_ERROR([--with-emscripten-target only applies to Emscripten])
-  ])
-], [
-  AS_VAR_IF([ac_sys_system], [Emscripten], [ac_sys_emscripten_target=browser])
-])
-AC_MSG_RESULT([$ac_sys_emscripten_target])
-
 dnl On Emscripten dlopen() requires -s MAIN_MODULE and -fPIC. The flags
 dnl disables dead code elimination and increases the size of the WASM module
 dnl by about 1.5 to 2MB. MAIN_MODULE defines __wasm_mutable_globals__.
@@ -1350,10 +1326,9 @@ AC_ARG_WITH([suffix],
     [EXEEXT=$with_suffix]
   )
 ], [
-  AS_CASE([$ac_sys_system/$ac_sys_emscripten_target],
-    [Emscripten/browser*], [EXEEXT=.js],
-    [Emscripten/node*], [EXEEXT=.js],
-    [WASI/*], [EXEEXT=.wasm],
+  AS_CASE([$ac_sys_system],
+    [Emscripten], [EXEEXT=.js],
+    [WASI], [EXEEXT=.wasm],
     [EXEEXT=]
   )
 ])
@@ -1638,16 +1613,16 @@ AC_MSG_CHECKING([HOSTRUNNER])
 AC_ARG_VAR([HOSTRUNNER], [Program to run CPython for the host platform])
 if test -z "$HOSTRUNNER"
 then
-  AS_CASE([$ac_sys_system/$ac_sys_emscripten_target],
-    [Emscripten/node*], [
+  AS_CASE([$ac_sys_system],
+    [Emscripten], [
       AC_PATH_TOOL([NODE], [node], [node])
       HOSTRUNNER="$NODE"
       AS_VAR_IF([host_cpu], [wasm64], [AS_VAR_APPEND([HOSTRUNNER], [" --experimental-wasm-memory64"])])
     ],
     dnl TODO: support other WASI runtimes
     dnl wasmtime starts the process with "/" as CWD. For OOT builds add the
     dnl directory containing _sysconfigdata to PYTHONPATH.
-    [WASI/*], [HOSTRUNNER='wasmtime run --wasm max-wasm-stack=16777216 --wasi preview2=n --env PYTHONPATH=/$(shell realpath --relative-to $(abs_srcdir) $(abs_builddir))/$(shell cat pybuilddir.txt):/Lib --dir $(srcdir)::/'],
+    [WASI], [HOSTRUNNER='wasmtime run --wasm max-wasm-stack=16777216 --wasi preview2=n --env PYTHONPATH=/$(shell realpath --relative-to $(abs_srcdir) $(abs_builddir))/$(shell cat pybuilddir.txt):/Lib --dir $(srcdir)::/'],
     [HOSTRUNNER='']
   )
 fi
@@ -1660,10 +1635,8 @@ if test -n "$HOSTRUNNER"; then
 fi
 
 # LIBRARY_DEPS, LINK_PYTHON_OBJS and LINK_PYTHON_DEPS variable
-AS_CASE([$ac_sys_system/$ac_sys_emscripten_target],
-  [Emscripten/browser*], [LIBRARY_DEPS='$(PY3LIBRARY) $(WASM_STDLIB) python.html python.worker.js'],
-  [LIBRARY_DEPS='$(PY3LIBRARY) $(EXPORTSYMS)']
-)
+LIBRARY_DEPS='$(PY3LIBRARY) $(EXPORTSYMS)'
+
 LINK_PYTHON_DEPS='$(LIBRARY_DEPS)'
 if test "$PY_ENABLE_SHARED" = 1 || test "$enable_framework" ; then
     LIBRARY_DEPS="\$(LDLIBRARY) $LIBRARY_DEPS"
@@ -2365,24 +2338,11 @@ AS_CASE([$ac_sys_system],
       AS_VAR_APPEND([LDFLAGS_NODIST], [" -sUSE_PTHREADS"])
       AS_VAR_APPEND([LINKFORSHARED], [" -sPROXY_TO_PTHREAD"])
     ])
-
-    AS_CASE([$ac_sys_emscripten_target],
-      [browser*], [
-        AS_VAR_IF([ac_sys_emscripten_target], [browser-debug], [wasm_debug=yes])
-        AS_VAR_APPEND([LINKFORSHARED], [" --preload-file=\$(WASM_ASSETS_DIR)"])
-        WASM_ASSETS_DIR=".\$(prefix)"
-        WASM_STDLIB="\$(WASM_ASSETS_DIR)/local/lib/python\$(VERSION)/os.py"
-        dnl separate-dwarf does not seem to work in Chrome DevTools Support.
-        WASM_LINKFORSHARED_DEBUG="-gsource-map --emit-symbol-map"
-      ],
-      [node*], [
-        AS_VAR_IF([ac_sys_emscripten_target], [node-debug], [wasm_debug=yes])
-        AS_VAR_APPEND([LDFLAGS_NODIST], [" --pre-js=\$(srcdir)/Tools/wasm/emscripten/node_pre.js"])
-        AS_VAR_APPEND([LDFLAGS_NODIST], [" -sALLOW_MEMORY_GROWTH -sNODERAWFS"])
-        AS_VAR_APPEND([LINKFORSHARED], [" -sEXIT_RUNTIME"])
-        WASM_LINKFORSHARED_DEBUG="-gseparate-dwarf --emit-symbol-map"
-      ]
-    )
+    AS_VAR_APPEND([LDFLAGS_NODIST], [" -sALLOW_MEMORY_GROWTH"])
+    dnl not completely sure whether or not we want -sEXIT_RUNTIME, keeping it for now.
+    AS_VAR_APPEND([LDFLAGS_NODIST], [" -sEXIT_RUNTIME"])
+    AS_VAR_APPEND([LDFLAGS_NODIST], [" --pre-js=\$(srcdir)/Tools/wasm/emscripten/node_pre.js"])
+    WASM_LINKFORSHARED_DEBUG="-gseparate-dwarf --emit-symbol-map"
 
     AS_VAR_IF([wasm_debug], [yes], [
       AS_VAR_APPEND([LDFLAGS_NODIST], [" -sASSERTIONS"])
@@ -7463,12 +7423,7 @@ AC_MSG_CHECKING([for --disable-test-modules])
 AC_ARG_ENABLE([test-modules],
   [AS_HELP_STRING([--disable-test-modules], [don't build nor install test modules])], [
   AS_VAR_IF([enable_test_modules], [yes], [TEST_MODULES=yes], [TEST_MODULES=no])
-], [
-  AS_CASE([$ac_sys_system/$ac_sys_emscripten_target],
-    [Emscripten/browser*], [TEST_MODULES=no],
-    [TEST_MODULES=yes]
-  )
-])
+], [TEST_MODULES=yes])
 AC_MSG_RESULT([$TEST_MODULES])
 AC_SUBST([TEST_MODULES])