Enable Rollup treeshaking pass by default, disable only for CLI builds (#944)

Author: lorisleiva

.changeset/pink-peaches-grab.md

@@ -0,0 +1,16 @@
+---
+'@codama/cli': patch
+'@codama/dynamic-codecs': patch
+'@codama/dynamic-parsers': patch
+'@codama/errors': patch
+'codama': patch
+'@codama/node-types': patch
+'@codama/nodes': patch
+'@codama/nodes-from-anchor': patch
+'@codama/renderers-core': patch
+'@codama/validators': patch
+'@codama/visitors': patch
+'@codama/visitors-core': patch
+---
+
+Enable Rollup treeshaking pass by default, disable only for CLI builds

packages/cli/tsup.config.ts

@@ -1,9 +1,23 @@
-import { defineConfig } from 'tsup';
+import { defineConfig, Options as TsupConfig } from 'tsup';
 
 import { getBuildConfig, getCliBuildConfig } from '../../tsup.config.base';
 
 export default defineConfig([
-    getBuildConfig({ format: 'cjs', platform: 'node' }),
-    getBuildConfig({ format: 'esm', platform: 'node' }),
-    getCliBuildConfig(),
+    removeAdditionalTreeShaking(getBuildConfig({ format: 'cjs', platform: 'node' })),
+    removeAdditionalTreeShaking(getBuildConfig({ format: 'esm', platform: 'node' })),
+    removeAdditionalTreeShaking(getCliBuildConfig()),
 ]);
+
+function removeAdditionalTreeShaking(config: TsupConfig): TsupConfig {
+    return {
+        ...config,
+
+        // Treeshaking already happens with esbuild but tsup offers this options
+        // for "better" treeshaking strategies using Rollup as an additional step.
+        // The issue is Rollup now uses the deprecated "assert" import keyword by default
+        // And tsup doesn't offer a way to change this behavior. Since the CLI package
+        // relies on using the "with" keyword to dynamically import JSON files,
+        // we can't use Rollup for treeshaking.
+        treeshake: false,
+    };
+}

tsup.config.base.ts

@@ -54,6 +54,7 @@ export function getBuildConfig(options: BuildOptions): TsupConfig {
         publicDir: true,
         pure: ['process'],
         sourcemap: format !== 'iife',
+        treeshake: true,
     };
 }