Generate source maps with -cheerp-sourcemap

Cheerp can generate source maps together with the final compiled JavaScript file:

Terminal window
/opt/cheerp/bin/clang++ file.cpp -o file.js -g

The standard -g option is used to generate debugging information in the frontend. The Cheerp-specific -cheerp-sourcemap option instructs Cheerp to output the source map file in the given file. You can of course use any name for the source map file.

  • -g Required to get the compiler to generate debugging metadata
  • -cheerp-sourcemap=filename Tells Cheerp where to output the sourcemap
  • -cheerp-sourcemap-prefix=path Tells Cheerp to remove the given prefix from all the source files paths that are stored inside the sourcemap.
  • -cheerp-sourcemap-standalone Tells Cheerp to include all sources into the sourcemap file. This makes it easier to debug using sourcemap since you only need to put the map file on the Web Server, instead of the whole source code. Since the map contains the sources you should remember not to deploy this file in production.


When sourcemaps are enabled you can:

  • Set break points in C++ code
  • Single-step through C++ code
  • See C++ code when an exception is raised


The sourcemap standard does not allow any kind of variable inspection or mapping source variable to compiled variables.

This means that it is not possible to watch the values of C++ variables or change them. We plan to enable this possibility when the standard will support it.

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