Add infrastructure to build and publish as wasm32 (#3840)

Co-authored-by: Ingvar Stepanyan <me@rreverser.com>

lib/libvips.js

@@ -41,15 +41,23 @@ const runtimePlatformArch = () => `${process.platform}${runtimeLibc()}-${process
 
 /* istanbul ignore next */
 const buildPlatformArch = () => {
+  if (isEmscripten()) {
+    return 'wasm32';
+  }
   /* eslint camelcase: ["error", { allow: ["^npm_config_"] }] */
   const { npm_config_arch, npm_config_platform, npm_config_libc } = process.env;
-  return `${npm_config_platform || process.platform}${npm_config_libc || runtimeLibc()}-${npm_config_arch || process.arch}`;
+  const libc = typeof npm_config_libc === 'string' ? npm_config_libc : runtimeLibc();
+  return `${npm_config_platform || process.platform}${libc}-${npm_config_arch || process.arch}`;
 };
 
 const buildSharpLibvipsIncludeDir = () => {
   try {
-    return require('@img/sharp-libvips-dev/include');
-  } catch {}
+    return require(`@img/sharp-libvips-dev-${buildPlatformArch()}/include`);
+  } catch {
+    try {
+      return require('@img/sharp-libvips-dev/include');
+    } catch {}
+  }
   /* istanbul ignore next */
   return '';
 };
@@ -64,12 +72,22 @@ const buildSharpLibvipsCPlusPlusDir = () => {
 
 const buildSharpLibvipsLibDir = () => {
   try {
-    return require(`@img/sharp-libvips-${buildPlatformArch()}/lib`);
-  } catch {}
+    return require(`@img/sharp-libvips-dev-${buildPlatformArch()}/lib`);
+  } catch {
+    try {
+      return require(`@img/sharp-libvips-${buildPlatformArch()}/lib`);
+    } catch {}
+  }
   /* istanbul ignore next */
   return '';
 };
 
+/* istanbul ignore next */
+const isEmscripten = () => {
+  const { CC } = process.env;
+  return Boolean(CC && CC.endsWith('/emcc'));
+};
+
 const isRosetta = () => {
   /* istanbul ignore next */
   if (process.platform === 'darwin' && process.arch === 'x64') {
@@ -81,7 +99,7 @@ const isRosetta = () => {
 
 /* istanbul ignore next */
 const spawnRebuild = () =>
-  spawnSync('node-gyp rebuild --directory=src', {
+  spawnSync(`node-gyp rebuild --directory=src ${isEmscripten() ? '--nodedir=emscripten' : ''}`, {
     ...spawnSyncOptions,
     stdio: 'inherit'
   }).status;

lib/sharp.js

@@ -12,7 +12,9 @@ const runtimePlatform = runtimePlatformArch();
 
 const paths = [
   `../src/build/Release/sharp-${runtimePlatform}.node`,
-  `@img/sharp-${runtimePlatform}/sharp.node`
+  '../src/build/Release/sharp-wasm32.node',
+  `@img/sharp-${runtimePlatform}/sharp.node`,
+  '@img/sharp-wasm32/sharp.node'
 ];
 
 const errors = [];
@@ -47,6 +49,8 @@ if (!module.exports) {
     help.push(`    npm install --force @img/sharp-${runtimePlatform}`);
   } else {
     help.push(`- Manually install libvips >= ${minimumLibvipsVersion}`);
+    help.push('- Add experimental WebAssembly-based dependencies:');
+    help.push('    npm install --cpu=wasm32 sharp');
   }
   if (isLinux && /symbol not found/i.test(messages)) {
     try {

lib/utility.js

@@ -59,11 +59,17 @@ let versions = {
 };
 /* istanbul ignore next */
 if (!libvipsVersion.isGlobal) {
-  try {
-    versions = require(`@img/sharp-${runtimePlatform}/versions`);
-  } catch (_) {
+  if (!libvipsVersion.isWasm) {
     try {
-      versions = require(`@img/sharp-libvips-${runtimePlatform}/versions`);
+      versions = require(`@img/sharp-${runtimePlatform}/versions`);
+    } catch (_) {
+      try {
+        versions = require(`@img/sharp-libvips-${runtimePlatform}/versions`);
+      } catch (_) {}
+    }
+  } else {
+    try {
+      versions = require('@img/sharp-wasm32/versions');
     } catch (_) {}
   }
 }