[commonjs] strictRequires indent with \t modifies multi-line string values.

[simonbuchan]

• Rollup Plugin Name: commonjs
• Rollup Plugin Version: 22.0.1
• Rollup Version: 2.77.2
• Operating System (or Browser):
• Node Version: v16.16.0
• Link to reproduction: https://replit.com/@simonbuchan/rollup-plugin-repro#output/bundle.js

Expected Behavior

Multiline-string values should be preserved.

Actual Behavior

Indent \t characters are blindly inserted into the multi-line string.

Additional Information

This particular issue seems to be due to:

plugins/packages/commonjs/src/transform-commonjs.js

Line 534 in add3a35

magicString.trim().indent('\t');

but there are other uses of magicString.indent("\t") in the code-base, e.g.:

plugins/packages/commonjs/src/generate-exports.js

Lines 12 to 16 in add3a35

	magicString
	.trim()
	.indent('\t')
	.prepend(`(function (${args.join(', ')}) {\n`)
	.append(`\n} (${passedArgs.join(', ')}));`);

The simple fix is just don't indent code - I doubt it would be simple to implement a correct source-map-preserving indent. Perhaps instead doing a transform from multi-line template strings to single-line escape codes would also work?

[lukastaegert]

Actually considering that the plugin is already parsing the entire code and knows all template literals, the fix is to pass an indentExclusionRanges array to the MagicString constructor and for every TemplateLiteral, push [start, end] into the array. This should actually be done for regular Literals as well as you can escape a line-break in a string. This is how Rollup does it https://github.com/rollup/rollup/blob/release-3.0.0/src/ast/nodes/TemplateLiteral.ts#L57-L57 https://github.com/rollup/rollup/blob/release-3.0.0/src/ast/nodes/Literal.ts#L88-L88, see also https://github.com/Rich-Harris/magic-string#usage

[simonbuchan]

As a workaround for now, I'm flattening multi-line strings with:

import * as babelTypes from "@babel/types"

import babel from "@rollup/plugin-babel";
import commonjs from "@rollup/plugin-commonjs";

export default {
  ...
  plugins: [
    ...
    babel({
      skipPreflightCheck: true,
      babelHelpers: "external",
      babelrc: false,
      configFile: false,
      plugins: [babelPluginFlattenTemplate()],
    }),
    commonjs(),
    ...
  ],
};

function babelPluginFlattenTemplate(): babel.PluginObj<unknown> {
  return {
    visitor: {
      TemplateElement(path) {
        const value = path.node.value;
        if (value.raw.includes("\n")) {
          path.replaceWith(
            babelTypes.templateElement({
              raw: value.raw.replace(/\n/g, "\\n"),
              cooked: value.cooked?.replace(/\n/g, "\\n"),
            }),
          );
        }
      },
    },
  };
}