Fixes for the emscripten build.

Author: nascheme

Tools/configure/conf_extlibs.py

@@ -163,12 +163,17 @@ def detect_sqlite3(v):
     """Detect sqlite3 and handle --enable-loadable-sqlite-extensions."""
     v.have_sqlite3 = False
     v.have_supported_sqlite3 = False
-    v.LIBSQLITE3_CFLAGS = ""
-    v.LIBSQLITE3_LIBS = "-lsqlite3"
 
-    # Emscripten port check (stub — pyconf.check_emscripten_port is a no-op)
+    # Emscripten port check — must run before defaults are set so that
+    # check_emscripten_port sees empty CFLAGS/LIBS and can set them.
     pyconf.check_emscripten_port("LIBSQLITE3", "-sUSE_SQLITE3")
 
+    # Set defaults only if not already provided (by emscripten port or user).
+    if not v.LIBSQLITE3_CFLAGS:
+        v.LIBSQLITE3_CFLAGS = ""
+    if not v.LIBSQLITE3_LIBS:
+        v.LIBSQLITE3_LIBS = "-lsqlite3"
+
     # pkg-config probe
     pkg = pyconf.find_prog("pkg-config")
     if pkg:

Tools/configure/conf_net.py

@@ -356,20 +356,26 @@ def check_getaddrinfo(v):
       return 1;
     }
     """
-        pyconf.checking("getaddrinfo bug")
-        if pyconf.cross_compiling:
-            if v.ac_sys_system in ("Linux-android", "iOS"):
-                ac_cv_buggy_getaddrinfo = False
-            elif v.enable_ipv6 != "":
-                ac_cv_buggy_getaddrinfo = (
-                    "no -- configured with --(en|dis)able-ipv6"
-                )
+        ac_cv_buggy_getaddrinfo = pyconf.cache_check(
+            "getaddrinfo bug", "ac_cv_buggy_getaddrinfo"
+        )
+        if ac_cv_buggy_getaddrinfo is None:
+            if pyconf.cross_compiling:
+                if v.ac_sys_system in ("Linux-android", "iOS"):
+                    ac_cv_buggy_getaddrinfo = False
+                elif v.enable_ipv6 != "":
+                    ac_cv_buggy_getaddrinfo = (
+                        "no -- configured with --(en|dis)able-ipv6"
+                    )
+                else:
+                    ac_cv_buggy_getaddrinfo = True
             else:
-                ac_cv_buggy_getaddrinfo = True
-        else:
-            ok = pyconf.run_check(GETADDRINFO_TEST)
-            ac_cv_buggy_getaddrinfo = not ok
-        pyconf.result(ac_cv_buggy_getaddrinfo)
+                ok = pyconf.run_check(GETADDRINFO_TEST)
+                ac_cv_buggy_getaddrinfo = not ok
+            pyconf.cache_store(
+                "ac_cv_buggy_getaddrinfo", ac_cv_buggy_getaddrinfo
+            )
+            pyconf.result(ac_cv_buggy_getaddrinfo)
     else:
         ac_cv_buggy_getaddrinfo = True
 

Tools/configure/conf_wasm.py

@@ -68,7 +68,7 @@ def setup_wasm_flags(v):
         _setup_wasi_flags(v)
 
     # Force/suppress ac_cv_func_dlopen for WASM dynamic linking
-    if v.enable_wasm_dynamic_linking is True:
+    if v.enable_wasm_dynamic_linking == "yes":
         v.ac_cv_func_dlopen = True
     elif v.enable_wasm_dynamic_linking is False:
         v.ac_cv_func_dlopen = False
@@ -95,7 +95,10 @@ def setup_wasm_flags(v):
 
 def _setup_emscripten_flags(v):
     """Set Emscripten-specific flags."""
-    v.wasm_debug = v.Py_DEBUG is True
+    # configure.ac: AS_VAR_IF([Py_DEBUG], [yes], [wasm_debug=yes], [wasm_debug=no])
+    # In autoconf Py_DEBUG is "true" not "yes", so this is currently always
+    # false.  We translate the comparison literally.
+    v.wasm_debug = v.Py_DEBUG == "yes"
 
     v.LINKFORSHARED += " -sALLOW_MEMORY_GROWTH -sINITIAL_MEMORY=20971520"
     v.LDFLAGS_NODIST += " -sWASM_BIGINT"
@@ -113,10 +116,10 @@ def _setup_emscripten_flags(v):
     v.LINKFORSHARED += " -sSTACK_SIZE=5MB"
     v.LINKFORSHARED += " -sTEXTDECODER=2"
 
-    if v.enable_wasm_dynamic_linking is True:
+    if v.enable_wasm_dynamic_linking == "yes":
         v.LINKFORSHARED += " -sMAIN_MODULE"
 
-    if v.enable_wasm_pthreads is True:
+    if v.enable_wasm_pthreads == "yes":
         v.CFLAGS_NODIST += " -pthread"
         v.LDFLAGS_NODIST += " -sUSE_PTHREADS"
         v.LINKFORSHARED += " -sPROXY_TO_PTHREAD"
@@ -150,7 +153,7 @@ def _setup_wasi_flags(v):
     )
     v.LIBS += " -lwasi-emulated-signal -lwasi-emulated-getpid -lwasi-emulated-process-clocks"
 
-    if v.enable_wasm_pthreads is True:
+    if v.enable_wasm_pthreads == "yes":
         v.CFLAGS_NODIST += " -target wasm32-wasi-threads -pthread"
         v.LDFLAGS_NODIST += (
             " -target wasm32-wasi-threads -pthread"

Tools/configure/pyconf.py

@@ -1396,6 +1396,47 @@ def result(value: Any) -> None:
 checking_fn = checking  # alias used by link_check to avoid param shadowing
 
 
+def cache_check(description: str, cache_var: str) -> Any:
+    """AC_CACHE_CHECK — check the cache before running a probe.
+
+    Prints "checking <description>..." and looks up *cache_var* in the
+    cache (which may have been pre-seeded from CONFIG_SITE).
+
+    Returns the cached value on a hit (also prints "(cached) <value>")
+    or None on a miss.  The caller is responsible for running the actual
+    probe on a miss and storing the result with
+    ``cache_store(cache_var, value)`` followed by ``result(value)``.
+
+    Typical usage::
+
+        val = pyconf.cache_check("getaddrinfo bug", "ac_cv_buggy_getaddrinfo")
+        if val is None:
+            val = <run probe>
+            pyconf.cache_store("ac_cv_buggy_getaddrinfo", val)
+            pyconf.result(val)
+    """
+    checking(description)
+    cached = cache.get(cache_var)
+    if cached is not None:
+        result(f"(cached) {_format_result(cached)}")
+        return cached
+    return None
+
+
+def cache_store(cache_var: str, value: Any) -> None:
+    """Store *value* in the cache under *cache_var*."""
+    cache[cache_var] = value
+
+
+def _format_result(value: Any) -> str:
+    """Format a cache value for display (True→'yes', False→'no')."""
+    if value is True:
+        return "yes"
+    if value is False:
+        return "no"
+    return str(value)
+
+
 def _flush_result(value: Any) -> None:
     """Emit result(value) if a checking() is pending, otherwise do nothing.
 
@@ -1763,7 +1804,14 @@ def _identify_compiler() -> None:
     except (subprocess.CalledProcessError, OSError):
         ver = ""
 
-    if "clang" in ver.lower():
+    # Detect emcc (Emscripten) before clang — emcc's --version output
+    # contains "clang" but autoconf identifies it as "emcc" via the
+    # __EMSCRIPTEN__ preprocessor macro.
+    if cc_basename == "emcc" or "emscripten" in ver.lower():
+        ac_cv_cc_name = "emcc"
+        ac_cv_gcc_compat = True
+        GCC = True  # emcc is gcc-compatible
+    elif "clang" in ver.lower():
         ac_cv_cc_name = "clang"
         ac_cv_gcc_compat = True
         GCC = True  # clang is gcc-compatible
@@ -3207,7 +3255,20 @@ def pkg_check_modules(pkg_var: str, module_spec: str) -> Any:
     Returns a SimpleNamespace with .cflags and .libs on success, None if
     pkg-config is unavailable or the module is not found.
     Sets <PKG_VAR>_CFLAGS and <PKG_VAR>_LIBS in pyconf.substs.
+
+    Like autoconf's PKG_CHECK_MODULES, if the CFLAGS/LIBS variables are
+    already set (e.g. by check_emscripten_port or the user), the pkg-config
+    query is skipped and the existing values are used.
     """
+    cflags_name = f"{pkg_var}_CFLAGS"
+    libs_name = f"{pkg_var}_LIBS"
+    # If variables are already set (by user, environment, or emscripten port),
+    # honour them without querying pkg-config — matches autoconf behaviour.
+    existing_cflags = getattr(vars, cflags_name, "")
+    existing_libs = getattr(vars, libs_name, "")
+    if existing_cflags or existing_libs:
+        ns = types.SimpleNamespace(cflags=existing_cflags, libs=existing_libs)
+        return ns
     pkg_config = shutil.which("pkg-config")
     if not pkg_config:
         return None
@@ -3224,10 +3285,10 @@ def pkg_check_modules(pkg_var: str, module_spec: str) -> Any:
         ).strip()
     except subprocess.CalledProcessError:
         return None
-    substs[f"{pkg_var}_CFLAGS"] = cflags
-    substs[f"{pkg_var}_LIBS"] = libs
-    setattr(vars, f"{pkg_var}_CFLAGS", cflags)
-    setattr(vars, f"{pkg_var}_LIBS", libs)
+    substs[cflags_name] = cflags
+    substs[libs_name] = libs
+    setattr(vars, cflags_name, cflags)
+    setattr(vars, libs_name, libs)
     ns = types.SimpleNamespace(cflags=cflags, libs=libs)
     return ns
 

Tools/configure/transpiler/lint_transpilable.py

@@ -157,9 +157,11 @@
         "stdlib_module_simple",
         "stdlib_module_set_na",
         # Misc
-        "run",
-        "macro",
+        "cache_check",
+        "cache_store",
         "is_defined",
+        "macro",
+        "run",
     }
 )
 

Tools/configure/transpiler/pyconf.awk

@@ -125,6 +125,27 @@ function _pyconf_print_cached(val) {
         printf "%s (cached)\n", val
 }
 
+# AC_CACHE_CHECK — check CACHE before running a probe.
+# Returns cached value on hit (prints "(cached) value"), "" on miss.
+function pyconf_cache_check(description, cache_var) {
+        pyconf_checking(description)
+        if (cache_var in CACHE) {
+                pyconf_result("(cached) " _pyconf_format_result(CACHE[cache_var]))
+                return CACHE[cache_var]
+        }
+        return ""
+}
+
+function pyconf_cache_store(cache_var, value) {
+        CACHE[cache_var] = value
+}
+
+function _pyconf_format_result(val) {
+        if (val == "yes") return "yes"
+        if (val == "no") return "no"
+        return val
+}
+
 function pyconf_warn(msg) {
         printf "WARNING: %s\n", msg > "/dev/stderr"
 }
@@ -1989,8 +2010,13 @@ function pyconf_find_compiler(user_cc, user_cpp, cc, cpp, ver) {
         }
         pyconf_CPP = cpp
         # Identify compiler via --version output
+        # Detect emcc before clang — emcc's version contains "clang"
         ver = _cmd_output(cc " --version 2>/dev/null")
-        if (tolower(ver) ~ /clang/) {
+        if (pyconf_basename(cc) == "emcc" || tolower(ver) ~ /emscripten/) {
+                pyconf_ac_cv_cc_name = "emcc"
+                pyconf_ac_cv_gcc_compat = "yes"
+                pyconf_GCC = "yes"
+        } else if (tolower(ver) ~ /clang/) {
                 pyconf_ac_cv_cc_name = "clang"
                 pyconf_ac_cv_gcc_compat = "yes"
                 pyconf_GCC = "yes"