467c911dc5
Every invariant `tests/ic` checked was IC-against-IC — clean == incremental, a no-op edit changes nothing, a body edit moves no interface cookie. An IC that is *consistently* wrong satisfies all of them, and that is exactly how two silent miscompilations survived. `koch bootic` has the same blind spot: it proves the compiler reproduces itself, not that it agrees with the reference backend. Two mechanisms, at different scales. **The oracle, in the metamorphic runner.** Every successful step is now also compiled with `nim c` and run, and the two outputs must agree. Unlike the hand-written `expect:` strings this needs no foresight from the test author: it compares everything the program does, not only what someone thought to print, which is what a silently-skipped destructor evades. `no-oracle` opts out. The format also grew the expressiveness the recent bug hunt showed was missing — every one of these described a state the suite could not reach: * `#!DELETE <file>` removes a module. Deleting a still-imported file moves no mtime, so nothing re-fires. * `#!FLAGS <switches>` changes the compiler switches between steps. A config change is not a file either. * `fails: <substring>` asserts that BOTH compilers reject the program with that text. Previously every step had to succeed, so the whole error path — and recovery from it — was untested. Six regression tests cover the eight bugs the last round fixed. `testament r <file>` now dispatches metamorphic tests like `testament cat ic`. **`testament --ic` runs the whole corpus through the incremental compiler**, so IC inherits ~10k programs with expected output instead of 30 bespoke tests. Two things had to change for that to mean anything: * `nimcacheDir` now keys on the `matrix:` entry too. Two matrix variants of one file are two different compilations; sharing a cache meant each run invalidated what the previous left — harmless for a backend that caches only object files, useless for an incremental one. * About half the corpus overrides the command wholesale (`cmd: "nim c --gc:arc $file"`), bypassing both `$target` and `$options`. Those are rewritten to `ic` and given a private cache. **Warm cache, hastur-style.** A generated warmup program pulling in `system` and the most-imported stdlib modules is compiled once per distinct compile configuration into `nimcache/ic_warmup_<hash>`, and each test's empty cache is seeded from it with mtimes preserved (nifmake compares output-mtime > input-mtime, so stamping the copies "now" re-fires the whole graph). Only program-independent artifacts are copied: the frontend NIFs and cookies plus the per-module `lower`/`cg` output. The `.c`/`.o` are left behind on purpose — the merge decision is whole-program, so they are re-rendered for every program anyway. `tests/destructor` (97 runs): `nim c` 35s cold / 32s warm; `nim ic` ~3m30 cold / **9.8s warm**. Compiler changes this required or uncovered: * `merge` read the live-module list from a manifest the driver writes instead of globbing `*.c.nif` off the nimcache. Globbing absorbed artifacts belonging to any other program sharing the directory — which is what made a prefilled cache produce undefined symbols at link. * The build-arg signature no longer includes `--icproject:`/`--icPreparsedConfig:` (they name where a build lives, not what it produces, so two caches holding identical artifacts got different signatures). The precompiled config still counts, by content hash, minus its `(nimcache …)` line. * `.s.deps` seeding is speculative and runs before the prune, so a sidecar entry that has gone stale (an import that a `when` no longer takes) can be dropped instead of lingering forever; a pruned module's scan artifacts are deleted so an edit-accumulated cache still matches a clean one. * A failed nifmake run no longer prints an `Error:` of its own. The children have already reported; adding a build-system status as the LAST error hid the compiler's real message from anything reading the final error — every reject-style test under `nim ic` said "nifmake failed with exit code: 1". * `--mm:hooks` fed the mm mode to an on/off switch and failed outright with "'on' or 'off' expected, but 'hooks' found". Pre-existing and unrelated to IC; only reachable through the explicit switch, since `--newruntime` sets `selectedGC` directly. Running `tests/destructor` under `--ic` currently leaves 10 failures. They are genuine IC defects, not harness noise (all 97 pass under `nim c`) — the clearest is `tglobaldestructor`: `graph.globalDestructors` is accumulated while injecting destructors into a module's top level, but the main module's `cg` — which emits the teardown — is a different process, so a module-level `var` with a `=destroy` is never destroyed. Same shape as the init/datInit metas, and it wants the same fix: record it in the `.c.nif` head. Validation: `koch bootic` reaches its byte-identical fixed point; `tests/ic` is 36/36; arc, destructor, macros, template, iter, closure, ccg, codegen, types and effects pass under `nim c`, with generics showing only its pre-existing failure. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Nim
This repository contains the Nim compiler, Nim's stdlib, tools, and documentation. For more information about Nim, including downloads and documentation for the latest release, check out Nim's website or bleeding edge docs.
Community
- The forum - the best place to ask questions and to discuss Nim.
- #nim IRC Channel (Libera Chat) - a place to discuss Nim in real-time. Also where most development decisions get made.
- Discord - an additional place to discuss Nim in real-time. Most channels there are bridged to IRC.
- Gitter - an additional place to discuss Nim in real-time. There is a bridge between Gitter and the IRC channel.
- Matrix - the main room to discuss Nim in real-time. Matrix space contains a list of rooms, most of them are bridged to IRC.
- Telegram - an additional place to discuss Nim in real-time. There is the official Telegram channel. Not bridged to IRC.
- Stack Overflow - a popular Q/A site for programming related topics that includes posts about Nim.
- GitHub Wiki - Misc user-contributed content.
Compiling
The compiler currently officially supports the following platform and architecture combinations:
| Operating System | Architectures Supported |
|---|---|
| Windows (Windows XP or greater) | x86 and x86_64 |
| Linux (most distributions) | x86, x86_64, ppc64, and armv6l |
| Mac OS X (10.4 or greater) | x86, x86_64, ppc64, and Apple Silicon (ARM64) |
More platforms are supported, however, they are not tested regularly and they may not be as stable as the above-listed platforms.
Compiling the Nim compiler is quite straightforward if you follow these steps:
First, the C source of an older version of the Nim compiler is needed to
bootstrap the latest version because the Nim compiler itself is written in the
Nim programming language. Those C sources are available within the
nim-lang/csources_v3 repository.
Next, to build from source you will need:
- A C compiler such as
gcc6.x/later or an alternative such asclang,Visual C++orIntel C++. It is recommended to usegcc6.x or later. - Either
gitorwgetto download the needed source repositories. - The
build-essentialpackage when usinggccon Ubuntu (and likely other distros as well). - On Windows MinGW 4.3.0 (GCC 8.10) is the minimum recommended compiler.
- Nim hosts a known working MinGW distribution:
Windows Note: Cygwin and similar POSIX runtime environments are not supported.
Then, if you are on a *nix system or Windows, the following steps should compile
Nim from source using gcc, git, and the koch build tool.
Note: The following commands are for the development version of the compiler. For most users, installing the latest stable version is enough. Check out the installation instructions on the website to do so: https://nim-lang.org/install.html.
For package maintainers: see packaging guidelines.
First, get Nim from GitHub:
git clone https://github.com/nim-lang/Nim.git
cd Nim
Next, run the appropriate build shell script for your platform:
build_all.sh(Linux, Mac)build_all.bat(Windows)
Finally, once you have finished the build steps (on Windows, Mac, or Linux) you
should add the bin directory to your PATH.
See also bootstrapping the compiler.
See also reproducible builds.
Koch
koch is the build tool used to build various parts of Nim and to generate
documentation and the website, among other things. The koch tool can also
be used to run the Nim test suite.
Assuming that you added Nim's bin directory to your PATH, you may execute
the tests using ./koch tests. The tests take a while to run, but you
can run a subset of tests by specifying a category (for example
./koch tests cat async).
For more information on the koch build tool please see the documentation
within the doc/koch.md file.
Nimble
nimble is Nim's package manager. To learn more about it, see the
nim-lang/nimble repository.
Contributors
This project exists thanks to all the people who contribute.
Contributing
See detailed contributing guidelines. We welcome all contributions to Nim regardless of how small or large they are. Everything from spelling fixes to new modules to be included in the standard library are welcomed and appreciated. Before you start contributing, you should familiarize yourself with the following repository structure:
bin/,build/- these directories are empty, but are used when Nim is built.compiler/- the compiler source code. Also includes plugins withincompiler/plugins.nimsuggest- the nimsuggest tool that previously lived in thenim-lang/nimsuggestrepository.config/- the configuration for the compiler and documentation generator.doc/- the documentation files in reStructuredText format.lib/- the standard library, including:pure/- modules in the standard library written in pure Nim.impure/- modules in the standard library written in pure Nim with dependencies written in other languages.wrappers/- modules that wrap dependencies written in other languages.
tests/- contains categorized tests for the compiler and standard library.tools/- the tools includingniminst(mostly invoked viakoch).koch.nim- the tool used to bootstrap Nim, generate C sources, build the website, and generate the documentation.
If you are not familiar with making a pull request using GitHub and/or git, please read this guide.
Ideally, you should make sure that all tests pass before submitting a pull request.
However, if you are short on time, you can just run the tests specific to your
changes by only running the corresponding categories of tests. CI verifies
that all tests pass before allowing the pull request to be accepted, so only
running specific tests should be harmless.
Integration tests should go in tests/untestable.
If you're looking for ways to contribute, please look at our issue tracker.
There are always plenty of issues labeled Easy; these should
be a good starting point for an initial contribution to Nim.
You can also help with the development of Nim by making donations. Donations can be made using:
If you have any questions feel free to submit a question on the Nim forum, or via IRC on the #nim channel.
Backers
Thank you to all our backers! [Become a backer]
Sponsors
Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]
You can also see a list of all our sponsors/backers from various payment services on the sponsors page of our website.
License
The compiler and the standard library are licensed under the MIT license, except for some modules which explicitly state otherwise. As a result, you may use any compatible license (essentially any license) for your own programs developed with Nim. You are explicitly permitted to develop commercial applications using Nim.
Please read the copying.txt file for more details.
Copyright © 2006-2026 Andreas Rumpf, all rights reserved.