nix flake show: add the description if it exists

(cherry picked from commit 8cd1d02f90eb9915e640c5d370d919fad9833c65)

nix flake show: Only print up to the first new line if it exists.

(cherry picked from commit 5281a44927bdb51bfe6e5de12262d815c98f6fe7)

add tests

(cherry picked from commit 74ae0fbdc70a5079a527fe143c4832d1357011f7)

Handle long strings, embedded new lines and empty descriptions

(cherry picked from commit 2ca7b3afdbbd983173a17fa0a822cf7623601367)

Account for total length of 80

(cherry picked from commit 1cc808c18cbaaf26aaae42bb1d7f7223f25dd364)

docs: add nix flake show description release note

fix: remove white space

nix flake show: trim length based on terminal size

test: account for terminal size

docs(flake-description): before and after commands; add myself to credits

Upstream-PR: https://github.com/NixOS/nix/pull/10980
Change-Id: Ie1c667dc816b3dd81e65a1f5395e57ea48ee0362

doc/manual/change-authors.yml

@@ -65,10 +65,17 @@ horrors:
 iFreilicht:
   github: iFreilicht
 
+isabelroses:
+  forgejo: isabelroses
+  github: isabelroses
+
 jade:
   forgejo: jade
   github: lf-
 
+kjeremy:
+  github: kjeremy
+
 kloenk:
   forgejo: kloenk
   github: kloenk

doc/manual/rl-next/nix-flake-show-description.md

@@ -0,0 +1,37 @@
+---
+synopsis: "Lix will now show the package descriptions in when running `nix flake show`."
+cls: [1540]
+issues: []
+credits: [kjeremy, isabelroses]
+category: Improvements
+---
+
+When running `nix flake show`, Lix will now show the package descriptions, if they exist.
+
+Before:
+
+```shell
+$ nix flake show
+path:/home/isabel/dev/lix-show?lastModified=1721736108&narHash=sha256-Zo8HP1ur7Q2b39hKUEG8EAh/opgq8xJ2jvwQ/htwO4Q%3D
+└───packages
+    └───x86_64-linux
+        ├───aNoDescription: package 'simple'
+        ├───bOneLineDescription: package 'simple'
+        ├───cMultiLineDescription: package 'simple'
+        ├───dLongDescription: package 'simple'
+        └───eEmptyDescription: package 'simple'
+```
+
+After:
+
+```shell
+$ nix flake show
+path:/home/isabel/dev/lix-show?lastModified=1721736108&narHash=sha256-Zo8HP1ur7Q2b39hKUEG8EAh/opgq8xJ2jvwQ/htwO4Q%3D
+└───packages
+    └───x86_64-linux
+        ├───aNoDescription: package 'simple'
+        ├───bOneLineDescription: package 'simple' - 'one line'
+        ├───cMultiLineDescription: package 'simple' - 'line one'
+        ├───dLongDescription: package 'simple' - 'abcdefghijklmnopqrstuvwxyz'
+        └───eEmptyDescription: package 'simple'
+```

package.nix

@@ -20,6 +20,7 @@
   doxygen,
   editline-lix ? __forDefaults.editline-lix,
   editline,
+  expect,
   git,
   gtest,
   jq,
@@ -253,6 +254,8 @@ stdenv.mkDerivation (finalAttrs: {
     ++ lib.optional (hostPlatform.canExecute buildPlatform) aws-sdk-cpp-nix
     ++ lib.optionals (finalAttrs.dontBuild) maybePropagatedInputs;
 
+  nativeCheckInputs = [ expect ];
+
   checkInputs = [
     gtest
     rapidcheck

src/nix/flake.cc

@@ -15,6 +15,7 @@
 #include "registry.hh"
 #include "eval-cache.hh"
 #include "markdown.hh"
+#include "terminal.hh"
 
 #include <nlohmann/json.hpp>
 #include <queue>
@@ -1225,25 +1226,42 @@ struct CmdFlakeShow : FlakeCommand, MixJSON
                 auto showDerivation = [&]()
                 {
                     auto name = visitor.getAttr(state->sName)->getString();
-                    if (json) {
                     std::optional<std::string> description;
                     if (auto aMeta = visitor.maybeGetAttr(state->sMeta)) {
                         if (auto aDescription = aMeta->maybeGetAttr(state->sDescription))
                             description = aDescription->getString();
                     }
+
+                    if (json) {
                         j.emplace("type", "derivation");
                         j.emplace("name", name);
                         if (description)
                             j.emplace("description", *description);
                     } else {
-                        logger->cout("%s: %s '%s'",
-                            headerPrefix,
+                        auto type =
                             attrPath.size() == 2 && attrPathS[0] == "devShell" ? "development environment" :
                             attrPath.size() >= 2 && attrPathS[0] == "devShells" ? "development environment" :
                             attrPath.size() == 3 && attrPathS[0] == "checks" ? "derivation" :
                             attrPath.size() >= 1 && attrPathS[0] == "hydraJobs" ? "derivation" :
-                            "package",
-                            name);
+                            "package";
+                        if (description && !description->empty()) {
+                            // Trim the string and only display the first line of the description.
+                            auto desc = nix::trim(*description);
+                            auto firstLineDesc = desc.substr(0, desc.find('\n'));
+
+                            std::string output = fmt("%s: %s '%s' - '%s'", headerPrefix, type, name, firstLineDesc);
+                            if (output.size() > getWindowSize().second) {
+                                // we resize to 4 less then the window size to account for the "...'" we append to
+                                // the final string, we also include the ' since that is removed when we truncate the string
+                                output.resize(getWindowSize().second - 4);
+                                output.append("...'");
+                            }
+
+                            logger->cout("%s", output.c_str());
+                        }
+                        else {
+                            logger->cout("%s: %s '%s'", headerPrefix, type, name);
+                        }
                     }
                 };
 

tests/functional/flakes/show.sh

@@ -85,3 +85,31 @@ assert show_output.legacyPackages.${builtins.currentSystem}.AAAAAASomeThingsFail
 assert show_output.legacyPackages.${builtins.currentSystem}.simple.name == "simple";
 true
 '
+
+cat >flake.nix<<EOF
+{
+  outputs = inputs: {
+    packages.$system = {
+      aNoDescription = import ./simple.nix;
+      bOneLineDescription = import ./simple.nix // { meta.description = "one line"; };
+      cMultiLineDescription = import ./simple.nix // { meta.description = ''
+         line one
+        line two
+      ''; };
+      dLongDescription = import ./simple.nix // { meta.description = ''
+        abcdefghijklmnopqrstuvwxyz
+      ''; };
+      eEmptyDescription = import ./simple.nix // { meta.description = ""; };
+    };
+  };
+}
+EOF
+unbuffer sh -c '
+  stty rows 20 cols 100
+  nix flake show > show-output.txt
+'
+test "$(awk -F '[:] ' '/aNoDescription/{print $NF}' ./show-output.txt)" = "package 'simple'"
+test "$(awk -F '[:] ' '/bOneLineDescription/{print $NF}' ./show-output.txt)" = "package 'simple' - 'one line'"
+test "$(awk -F '[:] ' '/cMultiLineDescription/{print $NF}' ./show-output.txt)" = "package 'simple' - 'line one'"
+test "$(awk -F '[:] ' '/dLongDescription/{print $NF}' ./show-output.txt)" = "package 'simple' - 'abcdefghijklmnopqrs...'"
+test "$(awk -F '[:] ' '/eEmptyDescription/{print $NF}' ./show-output.txt)" = "package 'simple'"