Add experimental esm target to ext/wasm/GNUmakefile to tell emcc to generate sqlite3.mjs (ES6 module) instead of sqlite3.js. Related to discussion at [forum:ed4596cf8496a39b].

FossilOrigin-Name: e55d8eba83012492d85418dc0faedce5896027ecc70295a5ca1826f61a5edbaf

ext/wasm/GNUmakefile

@@ -96,7 +96,7 @@ dir.dout := $(dir.wasm)/jswasm
 # dir.tmp = output dir for intermediary build files, as opposed to
 # end-user deliverables.
 dir.tmp := $(dir.wasm)/bld
-#CLEAN_FILES += $(wildcard $(dir.dout)/*) $(wildcard $(dir.tmp)/*)
+CLEAN_FILES += $(dir.tmp)/* $(dir.dout)/*
 ifeq (,$(wildcard $(dir.dout)))
   dir._tmp := $(shell mkdir -p $(dir.dout))
 endif
@@ -418,7 +418,20 @@ emcc.jsflags += -sWASM_BIGINT=$(emcc.WASM_BIGINT)
 # debugging info, _huge_.
 ########################################################################
 
-sqlite3.js := $(dir.dout)/sqlite3.js
+########################################################################
+# AN EXPERIMENT: undocumented Emscripten feature: if the target file
+# extension is "mjs", it defaults to ES6 module builds:
+# https://github.com/emscripten-core/emscripten/issues/14383
+ifeq (,$(filter esm,$(MAKECMDGOALS)))
+sqlite3.js.ext := js
+else
+esm.deps := $(filter-out esm,$(MAKECMDGOALS))
+esm: $(if $(esm.deps),$(esm.deps),all)
+sqlite3.js.ext := mjs
+endif
+# /esm
+########################################################################
+sqlite3.js := $(dir.dout)/sqlite3.$(sqlite3.js.ext)
 sqlite3.wasm := $(dir.dout)/sqlite3.wasm
 sqlite3-wasm.c := $(dir.api)/sqlite3-wasm.c
 # sqlite3-wasm.o vs sqlite3-wasm.c: building against the latter

manifest

@@ -1,5 +1,5 @@
-C Globally\sreplace\s''\swith\s""\sfor\sempty\sJS\sstrings\sto\splease\sC\spreprocessor.
-D 2022-11-03T21:21:10.223
+C Add\sexperimental\sesm\starget\sto\sext/wasm/GNUmakefile\sto\stell\semcc\sto\sgenerate\ssqlite3.mjs\s(ES6\smodule)\sinstead\sof\ssqlite3.js.\sRelated\sto\sdiscussion\sat\s[forum:ed4596cf8496a39b].
+D 2022-11-03T22:51:20.329
 F .fossil-settings/empty-dirs dbb81e8fc0401ac46a1491ab34a7f2c7c0452f2f06b54ebb845d024ca8283ef1
 F .fossil-settings/ignore-glob 35175cdfcf539b2318cb04a9901442804be81cd677d8b889fcc9149c21f239ea
 F LICENSE.md df5091916dbb40e6e9686186587125e1b2ff51f022cc334e886c19a0e9982724
@@ -487,7 +487,7 @@ F ext/userauth/sqlite3userauth.h 7f3ea8c4686db8e40b0a0e7a8e0b00fac13aa7a3
 F ext/userauth/user-auth.txt e6641021a9210364665fe625d067617d03f27b04
 F ext/userauth/userauth.c 7f00cded7dcaa5d47f54539b290a43d2e59f4b1eb5f447545fa865f002fc80cb
 F ext/wasm/EXPORTED_FUNCTIONS.fiddle.in 27450c8b8c70875a260aca55435ec927068b34cef801a96205adb81bdcefc65c
-F ext/wasm/GNUmakefile 78b64d110e66e18709c11437a74c29bc7855d85a713217db99127c7f304a332f
+F ext/wasm/GNUmakefile 3aa8c160705ab9d9d4d552a1f4e630925a65a27df216befe2e9a956904434c1d
 F ext/wasm/README-dist.txt 2d670b426fc7c613b90a7d2f2b05b433088fe65181abead970980f0a4a75ea20
 F ext/wasm/README.md ef39861aa21632fdbca0bdd469f78f0096f6449a720f3f39642594af503030e9
 F ext/wasm/api/EXPORTED_FUNCTIONS.sqlite3-api 9120c2f8f51fa85f46dcf4dcb6b12f4a807d428f6089b99cdb08d8ddfcfd88b2
@@ -2054,8 +2054,8 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 70ee6ee014bc4e2c1daa9b4a8909cf76ccecf32de1eb39055f20d3d0b1daa1bd
-R eaaf8a7ca25305cffe9e8f7e734e3ee8
+P e92e1f42bef94a1df29f66b4111ebfde93eba3759bc5d5a9c95f714508851346
+R 4cda7dd2938aaeec0aa59e31a649b872
 U stephan
-Z b98d96f31e9b735c045c03e6eefd13f8
+Z a58e3ce7633c7dbf732eedcffb48463a
 # Remove this line to create a well-formed Fossil manifest.

manifest.uuid

@@ -1 +1 @@
-e92e1f42bef94a1df29f66b4111ebfde93eba3759bc5d5a9c95f714508851346
+e55d8eba83012492d85418dc0faedce5896027ecc70295a5ca1826f61a5edbaf