Add pre-commit checks

The big ones here are `trim-trailing-whitespace` and `end-of-file-fixer`
(which makes sure that every file ends with exactly one newline
character).

Change-Id: Idca73b640883188f068f9903e013cf0d82aa1123

.clang-format

@@ -48,4 +48,3 @@ PointerAlignment: Middle
 SortIncludes: Never
 SpaceAfterCStyleCast: true
 SpaceAfterTemplateKeyword: false
-

.github/workflows/hydra_status.yml

@@ -17,4 +17,3 @@ jobs:
       with:
         fetch-depth: 0
     - run: bash scripts/check-hydra-status.sh
-

.gitignore

@@ -159,3 +159,5 @@ result-*
 buildtime.bin
 
 .envrc.local
+# We generate this with a Nix shell hook
+/.pre-commit-config.yaml

COPYING

@@ -55,7 +55,7 @@ modified by someone else and passed on, the recipients should know
 that what they have is not the original version, so that the original
 author's reputation will not be affected by problems that might be
 introduced by others.
-
+
   Finally, software patents pose a constant threat to the existence of
 any free program.  We wish to make sure that a company cannot
 effectively restrict the users of a free program by obtaining a
@@ -111,7 +111,7 @@ modification follow.  Pay close attention to the difference between a
 "work based on the library" and a "work that uses the library".  The
 former contains code derived from the library, whereas the latter must
 be combined with the library in order to run.
-
+
 		  GNU LESSER GENERAL PUBLIC LICENSE
    TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
 
@@ -158,7 +158,7 @@ Library.
   You may charge a fee for the physical act of transferring a copy,
 and you may at your option offer warranty protection in exchange for a
 fee.
-
+
   2. You may modify your copy or copies of the Library or any portion
 of it, thus forming a work based on the Library, and copy and
 distribute such modifications or work under the terms of Section 1
@@ -216,7 +216,7 @@ instead of to this License.  (If a newer version than version 2 of the
 ordinary GNU General Public License has appeared, then you can specify
 that version instead if you wish.)  Do not make any other change in
 these notices.
-
+
   Once this change is made in a given copy, it is irreversible for
 that copy, so the ordinary GNU General Public License applies to all
 subsequent copies and derivative works made from that copy.
@@ -267,7 +267,7 @@ Library will still fall under Section 6.)
 distribute the object code for the work under the terms of Section 6.
 Any executables containing that work also fall under Section 6,
 whether or not they are linked directly with the Library itself.
-
+
   6. As an exception to the Sections above, you may also combine or
 link a "work that uses the Library" with the Library to produce a
 work containing portions of the Library, and distribute that work
@@ -329,7 +329,7 @@ restrictions of other proprietary libraries that do not normally
 accompany the operating system.  Such a contradiction means you cannot
 use both them and the Library together in an executable that you
 distribute.
-
+
   7. You may place library facilities that are a work based on the
 Library side-by-side in a single library together with other library
 facilities not covered by this License, and distribute such a combined
@@ -370,7 +370,7 @@ subject to these terms and conditions.  You may not impose any further
 restrictions on the recipients' exercise of the rights granted herein.
 You are not responsible for enforcing compliance by third parties with
 this License.
-
+
   11. If, as a consequence of a court judgment or allegation of patent
 infringement or for any other reason (not limited to patent issues),
 conditions are imposed on you (whether by court order, agreement or
@@ -422,7 +422,7 @@ conditions either of that version or of any later version published by
 the Free Software Foundation.  If the Library does not specify a
 license version number, you may choose any version ever published by
 the Free Software Foundation.
-
+
   14. If you wish to incorporate parts of the Library into other free
 programs whose distribution conditions are incompatible with these,
 write to the author to ask for permission.  For software which is
@@ -456,7 +456,7 @@ SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
 DAMAGES.
 
 		     END OF TERMS AND CONDITIONS
-
+
            How to Apply These Terms to Your New Libraries
 
   If you develop a new library, and you want it to be of the greatest
@@ -500,5 +500,3 @@ necessary.  Here is a sample; alter the names:
   Ty Coon, President of Vice
 
 That's all there is to it!
-
-

doc/manual/rl-next/better-errors-in-nix-repl.md

@@ -37,4 +37,3 @@ error:
 
        error: uh oh!
 ```
-

doc/manual/src/_redirects

@@ -27,4 +27,3 @@
 /package-management/channels* /command-ref/nix-channel 301!
 
 /package-management/s3-substituter* /command-ref/new-cli/nix3-help-stores#s3-binary-cache-store 301!
-

doc/manual/src/architecture/architecture.md

@@ -112,4 +112,3 @@ Build inputs used as instructions to a build task are marked accordingly:
 |                                                                    |
 +--------------------------------------------------------------------+
 ```
-

doc/manual/src/command-ref/conf-file-prefix.md

@@ -67,4 +67,3 @@ Configuration options can be set on the command line, overriding the values set
 The `extra-` prefix is supported for settings that take a list of items (e.g. `--extra-trusted users alice` or `--option extra-trusted-users alice`).
 
 # Available settings
-

doc/manual/src/command-ref/nix-env/install.md

@@ -184,4 +184,3 @@ channel:
 ```console
 $ nix-env --file https://github.com/NixOS/nixpkgs/archive/nixos-14.12.tar.gz --install --attr firefox
 ```
-

doc/manual/src/command-ref/nix-env/list-generations.md

@@ -30,4 +30,3 @@ $ nix-env --list-generations
   97   2004-02-06 16:22:45
   98   2004-02-06 16:24:33   (current)
 ```
-

doc/manual/src/command-ref/nix-env/query.md

@@ -212,4 +212,3 @@ To show all packages in the latest revision of the Nixpkgs repository:
 ```console
 $ nix-env --file https://github.com/NixOS/nixpkgs/archive/master.tar.gz --query --available
 ```
-

doc/manual/src/command-ref/nix-env/set-flag.md

@@ -79,4 +79,3 @@ To make files from `binutils` take precedence over files from `gcc`:
 $ nix-env --set-flag priority 5 binutils
 $ nix-env --set-flag priority 10 gcc
 ```
-

doc/manual/src/command-ref/nix-env/set.md

@@ -27,4 +27,3 @@ contain just Firefox:
 ```console
 $ nix-env --profile /nix/var/nix/profiles/browser --set firefox
 ```
-

doc/manual/src/command-ref/nix-env/switch-generation.md

@@ -30,4 +30,3 @@ Switching will fail if the specified generation does not exist.
 $ nix-env --switch-generation 42
 switching from generation 50 to 42
 ```
-

doc/manual/src/command-ref/nix-env/upgrade.md

@@ -138,4 +138,3 @@ This is illustrated by the following examples:
     2.3a < 2.3c
     2.3pre1 < 2.3c
     2.3pre1 < 2.3q
-

doc/manual/src/command-ref/nix-store/add-fixed.md

@@ -32,4 +32,3 @@ This operation has the following options:
 $ nix-store --add-fixed sha256 ./hello-2.10.tar.gz
 /nix/store/3x7dwzq014bblazs7kq20p9hyzz0qh8g-hello-2.10.tar.gz
 ```
-

doc/manual/src/command-ref/nix-store/gc.md

@@ -69,4 +69,3 @@ To delete at least 100 MiBs of unreachable paths:
 ```console
 $ nix-store --gc --max-freed $((100 * 1024 * 1024))
 ```
-

doc/manual/src/command-ref/nix-store/opt-common.md

@@ -33,4 +33,3 @@ The following options are allowed for all `nix-store` operations, but may not al
   If there are multiple results, then multiple symlinks will be
   created by sequentially numbering symlinks beyond the first one
   (e.g., `foo`, `foo-2`, `foo-3`, and so on).
-

doc/manual/src/command-ref/nix-store/optimise.md

@@ -37,4 +37,3 @@ hashing files in `/nix/store/qhqx7l2f1kmwihc9bnxs7rc159hsxnf3-gcc-4.1.1'
 541838819 bytes (516.74 MiB) freed by hard-linking 54143 files;
 there are 114486 files with equal contents out of 215894 files in total
 ```
-

doc/manual/src/command-ref/nix-store/print-env.md

@@ -28,4 +28,3 @@ export stdenv; stdenv='/nix/store/7c8asx3yfrg5dg1gzhzyq2236zfgibnn-stdenv'
 export system; system='x86_64-linux'
 export _args; _args='-e /nix/store/9krlzvny65gdc8s7kpb6lkx8cd02c25c-default-builder.sh'
 ```
-

doc/manual/src/command-ref/nix-store/query.md

@@ -225,4 +225,3 @@ $ nix-store --query --roots $(which svn)
 /nix/var/nix/profiles/default-82-link
 /home/eelco/.local/state/nix/profiles/profile-97-link
 ```
-

doc/manual/src/command-ref/nix-store/read-log.md

@@ -35,4 +35,3 @@ ktorrent-2.2.1/
 ktorrent-2.2.1/NEWS
 ...
 ```
-

doc/manual/src/command-ref/nix-store/repair-path.md

@@ -32,4 +32,3 @@ $ nix-store --repair-path /nix/store/dj7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13
 fetching path `/nix/store/d7a81wsm1ijwwpkks3725661h3263p5-glibc-2.13'...
 …
 ```
-

doc/manual/src/command-ref/nix-store/serve.md

@@ -35,4 +35,3 @@ $ cat <<EOF >>/root/.ssh/authorized_keys
 command="nice -n20 nix-store --serve --write" ssh-rsa AAAAB3NzaC1yc2EAAAA...
 EOF
 ```
-

doc/manual/src/command-ref/nix-store/verify-path.md

@@ -26,4 +26,3 @@ To verify the integrity of the `svn` command and all its dependencies:
 ```console
 $ nix-store --verify-path $(nix-store --query --requisites $(which svn))
 ```
-

doc/manual/src/contributing/testing.md

@@ -289,4 +289,3 @@ search/replaced in it for each new build.
 The installer now supports a `--tarball-url-prefix` flag which _may_ have
 solved this need?
 -->
-

doc/manual/src/installation/uninstall.md

@@ -145,4 +145,3 @@ which you may remove.
 > complete. macOS (Catalina+) directly controls root directories and its
 > read-only root will prevent you from manually deleting the empty `/nix`
 > mountpoint.
-

doc/manual/src/language/operators.md

@@ -161,4 +161,3 @@ All comparison operators are implemented in terms of `<`, and the following equi
 Equivalent to `!`*b1* `||` *b2*.
 
 [Logical implication]: #logical-implication
-

flake.lock

@@ -3,11 +3,11 @@
     "flake-compat": {
       "flake": false,
       "locked": {
-        "lastModified": 1673956053,
+        "lastModified": 1696426674,
-        "narHash": "sha256-4gtG9iQuiKITOjNQQeQIpoIB6b16fm+504Ch3sNKLd8=",
+        "narHash": "sha256-kvjfFW7WAETZlt09AgDn1MrtKzP7t90Vf7vypd3OL1U=",
         "owner": "edolstra",
         "repo": "flake-compat",
-        "rev": "35bb57c0c8d8b62bbfd284272c928ceb64ddbde9",
+        "rev": "0f9255e01c2351cc7d116c072cb317785dd33b33",
         "type": "github"
       },
       "original": {
@@ -16,13 +16,52 @@
         "type": "github"
       }
     },
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1710146030,
+        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "gitignore": {
+      "inputs": {
+        "nixpkgs": [
+          "pre-commit-hooks",
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1709087332,
+        "narHash": "sha256-HG2cCnktfHsKV0s4XW83gU3F57gaTljL9KNSuG6bnQs=",
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "rev": "637db329424fd7e46cf4185293b9cc8c88c95394",
+        "type": "github"
+      },
+      "original": {
+        "owner": "hercules-ci",
+        "repo": "gitignore.nix",
+        "type": "github"
+      }
+    },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1709884566,
+        "lastModified": 1711481231,
-        "narHash": "sha256-NSYJg2sfdO/XS3L8XN/59Zhzn0dqWm7XtVnKI2mHq3w=",
+        "narHash": "sha256-J/fW3Xhm3WsJPNd8ksZmfMnol5aOG2qEMDPbOnNNdTQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "2be119add7b37dc535da2dd4cba68e2cf8d1517e",
+        "rev": "9d6ddb13cee3cc1192e4430277708c732685f38a",
         "type": "github"
       },
       "original": {
@@ -48,11 +87,56 @@
         "type": "github"
       }
     },
+    "pre-commit-hooks": {
+      "inputs": {
+        "flake-compat": [
+          "flake-compat"
+        ],
+        "flake-utils": "flake-utils",
+        "gitignore": "gitignore",
+        "nixpkgs": [
+          "nixpkgs"
+        ],
+        "nixpkgs-stable": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1711562502,
+        "narHash": "sha256-SLo1yf/lfozph818VME9Y56uhaZWY0juZcj/qJZPPrs=",
+        "owner": "9999years",
+        "repo": "git-hooks.nix",
+        "rev": "d2f6f9376c38fb0c48526720793a17f10cd3ac10",
+        "type": "github"
+      },
+      "original": {
+        "owner": "9999years",
+        "ref": "add-default-pre-commit-hooks",
+        "repo": "git-hooks.nix",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "flake-compat": "flake-compat",
         "nixpkgs": "nixpkgs",
-        "nixpkgs-regression": "nixpkgs-regression"
+        "nixpkgs-regression": "nixpkgs-regression",
+        "pre-commit-hooks": "pre-commit-hooks"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
       }
     }
   },

flake.nix

@@ -1,11 +1,23 @@
 {
   description = "The purely functional package manager";
 
-  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11-small";
+  inputs = {
-  inputs.nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.11-small";
-  inputs.flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
+    nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
+    pre-commit-hooks = {
+      # Can go back to `cachix/git-hooks.nix` when this is merged:
+      # https://github.com/cachix/git-hooks.nix/pull/401
+      url = "github:9999years/git-hooks.nix/add-default-pre-commit-hooks";
+      inputs = {
+        flake-compat.follows = "flake-compat";
+        nixpkgs.follows = "nixpkgs";
+        nixpkgs-stable.follows = "nixpkgs";
+      };
+    };
+    flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
+  };
 
-  outputs = { self, nixpkgs, nixpkgs-regression, flake-compat }:
+  outputs = { self, nixpkgs, nixpkgs-regression, pre-commit-hooks, flake-compat }:
 
     let
       inherit (nixpkgs) lib;
@@ -278,6 +290,49 @@
                 }
             );
         };
+
+        pre-commit = builtins.mapAttrs (system: pre-commit-lib: pre-commit-lib.run {
+          src = self;
+          hooks = {
+            no-commit-to-branch = {
+              enable = true;
+              settings.branch = ["main"];
+            };
+            check-case-conflicts.enable = true;
+            check-executables-have-shebangs = {
+              enable = true;
+              stages = [ "commit" ];
+            };
+            check-shebang-scripts-are-executable = {
+              enable = true;
+              stages = [ "commit" ];
+            };
+            check-symlinks = {
+              enable = true;
+              excludes = [ "^tests/functional/lang/symlink-resolution/broken$" ];
+            };
+            check-merge-conflicts.enable = true;
+            end-of-file-fixer = {
+              enable = true;
+              excludes = [
+                "\\.drv$"
+                "^tests/functional/lang/"
+              ];
+            };
+            mixed-line-endings = {
+              enable = true;
+              excludes = [ "^tests/functional/lang/" ];
+            };
+            # TODO: Once the test suite is nicer, clean up and start
+            # enforcing trailing whitespace on tests that don't explicitly
+            # check for it.
+            trim-trailing-whitespace = {
+              enable = true;
+              stages = [ "commit" ];
+              excludes = [ "^tests/functional/lang/" ];
+            };
+          };
+        }) pre-commit-hooks.lib;
       };
 
       checks = forAllSystems (system: let
@@ -295,6 +350,7 @@
         nixpkgsLibTests = self.hydraJobs.tests.nixpkgsLibTests.${system};
         rl-next = rl-next-check "rl-next" ./doc/manual/rl-next;
         rl-next-dev = rl-next-check "rl-next-dev" ./doc/manual/rl-next-dev;
+        pre-commit = self.hydraJobs.pre-commit.${system};
       } // (lib.optionalAttrs (builtins.elem system linux64BitSystems)) {
         dockerImage = self.hydraJobs.dockerImage.${system};
       });
@@ -340,6 +396,7 @@
               busybox-sandbox-shell = pkgs.busybox-sandbox-shell or pkgs.default-busybox-sandbox;
               forDevShell = true;
             };
+            pre-commit = self.hydraJobs.pre-commit.${pkgs.system} or {};
           in
             (nix.override {
               buildUnreleasedNotes = true;
@@ -348,6 +405,7 @@
               # Required for clang-tidy checks
               buildInputs = prev.buildInputs
                 ++ [ pkgs.just ]
+                ++ lib.optional (pre-commit ? enabledPackages) pre-commit.enabledPackages
                 ++ lib.optionals (stdenv.cc.isClang) [ pkgs.llvmPackages.llvm pkgs.llvmPackages.clang-unwrapped.dev ];
               nativeBuildInputs = prev.nativeBuildInputs
                 ++ lib.optional (stdenv.cc.isClang && !stdenv.buildPlatform.isDarwin) pkgs.buildPackages.bear
@@ -379,6 +437,8 @@
 
                 # Make bash completion work.
                 XDG_DATA_DIRS+=:$out/share
+
+                ${lib.optionalString (pre-commit ? shellHook) pre-commit.shellHook}
               '';
             } // lib.optionalAttrs (stdenv.buildPlatform.isLinux && pkgs.glibcLocales != null) {
               # Required to make non-NixOS Linux not complain about missing locale files during configure in a dev shell

maintainers/release-process.md

@@ -193,4 +193,3 @@ release:
 ## Recovering from mistakes
 
 `upload-release.pl` should be idempotent. For instance a wrong `IS_LATEST` value can be fixed that way, by running the script on the actual latest release.
-

meson/run-test.py

@@ -84,4 +84,3 @@ except Exception as e:
     print(f'{name}: INTERNAL ERROR running test ({sys.argv}): {e}', file=sys.stderr)
     print(f'this is a bug in {name}')
     sys.exit(99)
-

src/libstore/build/personality.hh

@@ -8,5 +8,3 @@ namespace nix {
 void setPersonality(std::string_view system);
 
 }
-
-

src/libutil/thread-pool.cc

@@ -152,5 +152,3 @@ void ThreadPool::doWork(bool mainThread)
 }
 
 }
-
-

tests/functional/ca/build-dry.sh

@@ -3,4 +3,3 @@ source common.sh
 export NIX_TESTS_CA_BY_DEFAULT=1
 
 cd .. && source build-dry.sh
-

tests/functional/ca/import-derivation.sh

@@ -3,4 +3,3 @@ source common.sh
 export NIX_TESTS_CA_BY_DEFAULT=1
 
 cd .. && source import-derivation.sh
-

tests/functional/ca/nix-shell.sh

@@ -5,4 +5,3 @@ source common.sh
 CONTENT_ADDRESSED=true
 cd ..
 source ./nix-shell.sh
-

tests/functional/ca/nondeterministic.nix

@@ -32,4 +32,3 @@ rec {
     '';
   };
 }
-

tests/functional/ca/post-hook.sh

@@ -7,5 +7,3 @@ requireDaemonNewerThan "2.4pre20210626"
 export NIX_TESTS_CA_BY_DEFAULT=1
 cd ..
 source ./post-hook.sh
-
-

tests/functional/fetchClosure.sh

@@ -147,4 +147,3 @@ expectStderr 1 nix eval -v --raw --expr "
     inputAddressed = true;
   }
 " | grepQuiet 'error.*The store object referred to by.*fromPath.* at .* is not input-addressed, but .*inputAddressed.* is set to .*true.*'
-

tests/functional/flakes/circular.sh

@@ -47,4 +47,3 @@ nix flake update b --flake $flakeA
 
 # Test list-inputs with circular dependencies
 nix flake metadata $flakeA
-

tests/functional/flakes/run.sh

@@ -26,4 +26,3 @@ nix run --no-write-lock-file .#pkgAsPkg
 ! nix run --no-write-lock-file .#appAsPkg || fail "elements of 'apps' should be of type 'app'"
 
 clearStore
-

tests/functional/fmt.simple.sh

@@ -1 +1,3 @@
+#!/usr/bin/env bash
+
 echo Formatting: "${@}"

tests/functional/function-trace.sh

@@ -1,3 +1,5 @@
+#!/usr/bin/env bash
+
 source common.sh
 
 set +x

tests/functional/init.sh

@@ -1,3 +1,5 @@
+#!/usr/bin/env bash
+
 # Don't start the daemon
 source common/vars-and-functions.sh
 

tests/functional/lang.sh

@@ -1,3 +1,5 @@
+#!/usr/bin/env bash
+
 source common.sh
 
 set -o pipefail

tests/functional/linux-sandbox-cert-test.nix

@@ -27,4 +27,3 @@ mkDerivation (
     normal = { };
   }.${mode}
 )
-

tests/functional/nix-channel.sh

@@ -63,4 +63,3 @@ grepQuiet 'item.*attrPath="foo".*name="dependencies-top"' $TEST_ROOT/meta.xml
 # Do an install.
 nix-env -i dependencies-top
 [ -e $TEST_HOME/.nix-profile/foobar ]
-

tests/functional/repl_characterization/data/basic.ast

@@ -14,4 +14,3 @@ Commentary "the blank below should be chomped"
 Command "command three"
 Commentary ""
 Output "meow output"
-Output ""

tests/functional/repl_characterization/data/basic.test

@@ -14,4 +14,3 @@ the blank below should be chomped
   nix-repl> command three
 
   meow output
-

tests/unit/libutil/chunked-vector.cc

@@ -51,4 +51,3 @@ namespace nix {
     }
 
 }
-

tests/unit/libutil/git.cc

@@ -30,4 +30,3 @@ namespace nix {
         ASSERT_EQ(res->reference, "refs/head/main");
     }
 }
-

tests/unit/libutil/references.cc

@@ -43,4 +43,3 @@ INSTANTIATE_TEST_CASE_P(
 );
 
 }
-