Merge pull request #11167 from NixOS/repl-test-rejiggle

Fix repl test for `buildReadlineNoMarkdown`

src/libcmd/markdown.cc

@@ -1,21 +1,23 @@
 #include "markdown.hh"
-#include "util.hh"
+#include "environment-variables.hh"
+#include "error.hh"
 #include "finally.hh"
 #include "terminal.hh"
 
 #if HAVE_LOWDOWN
-# include <sys/queue.h>
-# include <lowdown.h>
+#  include <sys/queue.h>
+#  include <lowdown.h>
 #endif
 
 namespace nix {
 
-std::string renderMarkdownToTerminal(std::string_view markdown)
-{
 #if HAVE_LOWDOWN
+static std::string doRenderMarkdownToTerminal(std::string_view markdown)
+{
     int windowWidth = getWindowSize().second;
 
-    struct lowdown_opts opts {
+    struct lowdown_opts opts
+    {
         .type = LOWDOWN_TERM,
         .maxdepth = 20,
         .cols = (size_t) std::max(windowWidth - 5, 60),
@@ -51,9 +53,21 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         throw Error("allocation error while rendering Markdown");
 
     return filterANSIEscapes(std::string(buf->data, buf->size), !isTTY());
-#else
-    return std::string(markdown);
-#endif
 }
 
+std::string renderMarkdownToTerminal(std::string_view markdown)
+{
+    if (auto e = getEnv("_NIX_TEST_RAW_MARKDOWN"); e && *e == "1")
+        return std::string(markdown);
+    else
+        return doRenderMarkdownToTerminal(markdown);
 }
+
+#else
+std::string renderMarkdownToTerminal(std::string_view markdown)
+{
+    return std::string(markdown);
+}
+#endif
+
+} // namespace nix

src/libcmd/markdown.hh

@@ -1,10 +1,17 @@
 #pragma once
 ///@file
 
-#include "types.hh"
+#include <string_view>
 
 namespace nix {
 
+/**
+ * Render the given Markdown text to the terminal.
+ *
+ * If Nix is compiled without Markdown support, this function will return the input text as-is.
+ *
+ * The renderer takes into account the terminal width, and wraps text accordingly.
+ */
 std::string renderMarkdownToTerminal(std::string_view markdown);
 
 }

src/libcmd/repl-interacter.cc

@@ -19,6 +19,7 @@ extern "C" {
 #include "repl-interacter.hh"
 #include "file-system.hh"
 #include "repl.hh"
+#include "environment-variables.hh"
 
 namespace nix {
 
@@ -175,10 +176,23 @@ bool ReadlineLikeInteracter::getLine(std::string & input, ReplPromptType promptT
         return true;
     }
 
+    // editline doesn't echo the input to the output when non-interactive, unlike readline
+    // this results in a different behavior when running tests. The echoing is
+    // quite useful for reading the test output, so we add it here.
+    if (auto e = getEnv("_NIX_TEST_REPL_ECHO"); s && e && *e == "1")
+    {
+#ifndef USE_READLINE
+        // This is probably not right for multi-line input, but we don't use that
+        // in the characterisation tests, so it's fine.
+        std::cout << promptForType(promptType) << s << std::endl;
+#endif
+    }
+
     if (!s)
         return false;
     input += s;
     input += '\n';
+
     return true;
 }
 

src/libcmd/repl.cc

@@ -217,7 +217,7 @@ ReplExitStatus NixRepl::mainLoop()
                 case ProcessLineResult::PromptAgain:
                     break;
                 default:
-                    abort();
+                    unreachable();
             }
         } catch (ParseError & e) {
             if (e.msg().find("unexpected end of file") != std::string::npos) {

src/libexpr/attr-path.cc

@@ -134,7 +134,7 @@ std::pair<SourcePath, uint32_t> findPackageFilename(EvalState & state, Value & v
         return {SourcePath{path.accessor, CanonPath(fn.substr(0, colon))}, lineno};
     } catch (std::invalid_argument & e) {
         fail();
-        abort();
+        unreachable();
     }
 }
 

src/libexpr/eval-gc.cc

@@ -86,7 +86,9 @@ void fixupBoehmStackPointer(void ** sp_ptr, void * _pthread_id)
 {
     void *& sp = *sp_ptr;
     auto pthread_id = reinterpret_cast<pthread_t>(_pthread_id);
+#  ifndef __APPLE__
     pthread_attr_t pattr;
+#  endif
     size_t osStackSize;
     // The low address of the stack, which grows down.
     void * osStackLimit;

src/libexpr/eval.cc

@@ -149,7 +149,7 @@ std::string_view showType(ValueType type, bool withArticle)
         case nFloat: return WA("a", "float");
         case nThunk: return WA("a", "thunk");
     }
-    abort();
+    unreachable();
 }
 
 
@@ -780,7 +780,7 @@ void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr &
             case ReplExitStatus::Continue:
                 break;
             default:
-                abort();
+                unreachable();
         }
     }
 }
@@ -1149,7 +1149,7 @@ inline void EvalState::evalAttrs(Env & env, Expr * e, Value & v, const PosIdx po
 
 void Expr::eval(EvalState & state, Env & env, Value & v)
 {
-    abort();
+    unreachable();
 }
 
 
@@ -1582,7 +1582,7 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                                 .withFrame(*fun.payload.lambda.env, lambda)
                                 .debugThrow();
                         }
-                    abort(); // can't happen
+                    unreachable();
                 }
             }
 

src/libexpr/nixexpr.cc

@@ -25,7 +25,7 @@ std::ostream & operator <<(std::ostream & str, const SymbolStr & symbol)
 
 void Expr::show(const SymbolTable & symbols, std::ostream & str) const
 {
-    abort();
+    unreachable();
 }
 
 void ExprInt::show(const SymbolTable & symbols, std::ostream & str) const
@@ -271,7 +271,7 @@ std::string showAttrPath(const SymbolTable & symbols, const AttrPath & attrPath)
 
 void Expr::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
-    abort();
+    unreachable();
 }
 
 void ExprInt::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)

src/libexpr/primops.cc

@@ -426,7 +426,7 @@ static void prim_typeOf(EvalState & state, const PosIdx pos, Value * * args, Val
             t = args[0]->external()->typeOf();
             break;
         case nFloat: t = "float"; break;
-        case nThunk: abort();
+        case nThunk: unreachable();
     }
     v.mkString(t);
 }

src/libexpr/print-ambiguous.cc

@@ -94,7 +94,7 @@ void printAmbiguous(
         break;
     default:
         printError("Nix evaluator internal error: printAmbiguous: invalid value type");
-        abort();
+        unreachable();
     }
 }
 

src/libexpr/print.cc

@@ -475,7 +475,7 @@ private:
             else
                 output << "primop";
         } else {
-            abort();
+            unreachable();
         }
 
         output << "»";
@@ -504,7 +504,7 @@ private:
             if (options.ansiColors)
                     output << ANSI_NORMAL;
         } else {
-            abort();
+            unreachable();
         }
     }
 

src/libexpr/symbol-table.hh

@@ -7,6 +7,7 @@
 
 #include "types.hh"
 #include "chunked-vector.hh"
+#include "error.hh"
 
 namespace nix {
 
@@ -113,7 +114,7 @@ public:
     SymbolStr operator[](Symbol s) const
     {
         if (s.id == 0 || s.id > store.size())
-            abort();
+            unreachable();
         return SymbolStr(store[s.id - 1]);
     }
 

src/libexpr/value.hh

@@ -285,7 +285,7 @@ public:
         if (invalidIsThunk)
             return nThunk;
         else
-            abort();
+            unreachable();
     }
 
     inline void finishValue(InternalType newType, Payload newPayload)

src/libfetchers/attrs.cc

@@ -33,7 +33,7 @@ nlohmann::json attrsToJSON(const Attrs & attrs)
             json[attr.first] = *v;
         } else if (auto v = std::get_if<Explicit<bool>>(&attr.second)) {
             json[attr.first] = v->t;
-        } else abort();
+        } else unreachable();
     }
     return json;
 }
@@ -99,7 +99,7 @@ std::map<std::string, std::string> attrsToQuery(const Attrs & attrs)
             query.insert_or_assign(attr.first, *v);
         } else if (auto v = std::get_if<Explicit<bool>>(&attr.second)) {
             query.insert_or_assign(attr.first, v->t ? "1" : "0");
-        } else abort();
+        } else unreachable();
     }
     return query;
 }

src/libmain/loggers.cc

@@ -36,7 +36,7 @@ Logger * makeDefaultLogger() {
         return logger;
     }
     default:
-        abort();
+        unreachable();
     }
 }
 

src/libstore/build/drv-output-substitution-goal.hh

@@ -36,7 +36,7 @@ public:
     Co init() override;
     Co realisationFetched(std::shared_ptr<const Realisation> outputInfo, nix::ref<nix::Store> sub);
 
-    void timedOut(Error && ex) override { abort(); };
+    void timedOut(Error && ex) override { unreachable(); };
 
     std::string key() override;
 

src/libstore/build/goal.hh

@@ -400,12 +400,12 @@ public:
 
     virtual void handleChildOutput(Descriptor fd, std::string_view data)
     {
-        abort();
+        unreachable();
     }
 
     virtual void handleEOF(Descriptor fd)
     {
-        abort();
+        unreachable();
     }
 
     void trace(std::string_view s);

src/libstore/build/substitution-goal.hh

@@ -50,7 +50,7 @@ public:
     PathSubstitutionGoal(const StorePath & storePath, Worker & worker, RepairFlag repair = NoRepair, std::optional<ContentAddress> ca = std::nullopt);
     ~PathSubstitutionGoal();
 
-    void timedOut(Error && ex) override { abort(); };
+    void timedOut(Error && ex) override { unreachable(); };
 
     /**
      * We prepend "a$" to the key name to ensure substitution goals

src/libstore/build/worker.cc

@@ -216,7 +216,7 @@ void Worker::childStarted(GoalPtr goal, const std::set<MuxablePipePollState::Com
             nrLocalBuilds++;
             break;
         default:
-            abort();
+            unreachable();
         }
     }
 }
@@ -239,7 +239,7 @@ void Worker::childTerminated(Goal * goal, bool wakeSleepers)
             nrLocalBuilds--;
             break;
         default:
-            abort();
+            unreachable();
         }
     }
 

src/libstore/daemon.cc

@@ -33,7 +33,7 @@ Sink & operator << (Sink & sink, const Logger::Fields & fields)
             sink << f.i;
         else if (f.type == Logger::Field::tString)
             sink << f.s;
-        else abort();
+        else unreachable();
     }
     return sink;
 }

src/libstore/gc.cc

@@ -559,7 +559,7 @@ void LocalStore::collectGarbage(const GCOptions & options, GCResults & results)
                        non-blocking flag from the server socket, so
                        explicitly make it blocking. */
                     if (fcntl(fdClient.get(), F_SETFL, fcntl(fdClient.get(), F_GETFL) & ~O_NONBLOCK) == -1)
-                        abort();
+                        panic("Could not set non-blocking flag on client socket");
 
                     while (true) {
                         try {

src/libstore/globals.cc

@@ -297,7 +297,7 @@ template<> std::string BaseSetting<SandboxMode>::to_string() const
     if (value == smEnabled) return "true";
     else if (value == smRelaxed) return "relaxed";
     else if (value == smDisabled) return "false";
-    else abort();
+    else unreachable();
 }
 
 template<> void BaseSetting<SandboxMode>::convertToArg(Args & args, const std::string & category)

src/libstore/nar-info-disk-cache.cc

@@ -164,7 +164,7 @@ public:
     Cache & getCache(State & state, const std::string & uri)
     {
         auto i = state.caches.find(uri);
-        if (i == state.caches.end()) abort();
+        if (i == state.caches.end()) unreachable();
         return i->second;
     }
 
@@ -211,7 +211,7 @@ public:
 
             {
                 auto r(state->insertCache.use()(uri)(time(0))(storeDir)(wantMassQuery)(priority));
-                if (!r.next()) { abort(); }
+                if (!r.next()) { unreachable(); }
                 ret.id = (int) r.getInt(0);
             }
 

src/libstore/unix/build/local-derivation-goal.cc

@@ -165,7 +165,7 @@ void LocalDerivationGoal::killSandbox(bool getStats)
             buildResult.cpuSystem = stats.cpuSystem;
         }
         #else
-        abort();
+        unreachable();
         #endif
     }
 

src/libstore/unix/pathlocks.cc

@@ -45,7 +45,7 @@ bool lockFile(Descriptor desc, LockType lockType, bool wait)
     if (lockType == ltRead) type = LOCK_SH;
     else if (lockType == ltWrite) type = LOCK_EX;
     else if (lockType == ltNone) type = LOCK_UN;
-    else abort();
+    else unreachable();
 
     if (wait) {
         while (flock(desc, type) != 0) {

src/libutil/chunked-vector.hh

@@ -6,6 +6,8 @@
 #include <vector>
 #include <limits>
 
+#include "error.hh"
+
 namespace nix {
 
 /**
@@ -30,7 +32,7 @@ private:
     auto & addChunk()
     {
         if (size_ >= std::numeric_limits<uint32_t>::max() - ChunkSize)
-            abort();
+            unreachable();
         chunks.emplace_back();
         chunks.back().reserve(ChunkSize);
         return chunks.back();

src/libutil/error.cc

@@ -1,3 +1,5 @@
+#include <algorithm>
+
 #include "error.hh"
 #include "environment-variables.hh"
 #include "signals.hh"
@@ -430,4 +432,36 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s
     return out;
 }
 
+/** Write to stderr in a robust and minimal way, considering that the process
+ * may be in a bad state.
+ */
+static void writeErr(std::string_view buf)
+{
+    while (!buf.empty()) {
+        auto n = write(STDERR_FILENO, buf.data(), buf.size());
+        if (n < 0) {
+            if (errno == EINTR) continue;
+            abort();
+        }
+        buf = buf.substr(n);
+    }
+}
+
+void panic(std::string_view msg)
+{
+    writeErr("\n\n" ANSI_RED "terminating due to unexpected unrecoverable internal error: " ANSI_NORMAL );
+    writeErr(msg);
+    writeErr("\n");
+    abort();
+}
+
+void panic(const char * file, int line, const char * func)
+{
+    char buf[512];
+    int n = snprintf(buf, sizeof(buf), "Unexpected condition in %s at %s:%d", func, file, line);
+    if (n < 0)
+        panic("Unexpected condition and could not format error message");
+    panic(std::string_view(buf, std::min(static_cast<int>(sizeof(buf)), n)));
+}
+
 }

src/libutil/error.hh

@@ -273,4 +273,24 @@ using NativeSysError =
  */
 void throwExceptionSelfCheck();
 
+/**
+ * Print a message and abort().
+ */
+[[noreturn]]
+void panic(std::string_view msg);
+
+/**
+ * Print a basic error message with source position and abort().
+ * Use the unreachable() macro to call this.
+ */
+[[noreturn]]
+void panic(const char * file, int line, const char * func);
+
+/**
+ * Print a basic error message with source position and abort().
+ *
+ * @note: This assumes that the logger is operational
+ */
+#define unreachable() (::nix::panic(__FILE__, __LINE__, __func__))
+
 }

src/libutil/file-content-address.cc

@@ -63,7 +63,7 @@ std::string_view renderFileIngestionMethod(FileIngestionMethod method)
     case FileIngestionMethod::Git:
         return "git";
     default:
-        abort();
+        unreachable();
     }
 }
 

src/libutil/fs-sink.cc

@@ -53,7 +53,7 @@ void copyRecursive(
         throw Error("file '%1%' has an unsupported type", from);
 
     default:
-        abort();
+        unreachable();
     }
 }
 

src/libutil/git.cc

@@ -201,7 +201,7 @@ std::optional<Mode> convertMode(SourceAccessor::Type type)
     case SourceAccessor::tRegular:   return Mode::Regular;
     case SourceAccessor::tDirectory: return Mode::Directory;
     case SourceAccessor::tMisc:      return std::nullopt;
-    default: abort();
+    default: unreachable();
     }
 }
 

src/libutil/hash.cc

@@ -25,7 +25,7 @@ static size_t regularHashSize(HashAlgorithm type) {
     case HashAlgorithm::SHA256: return sha256HashSize;
     case HashAlgorithm::SHA512: return sha512HashSize;
     }
-    abort();
+    unreachable();
 }
 
 

src/libutil/logging.cc

@@ -189,7 +189,7 @@ struct JSONLogger : Logger {
             else if (f.type == Logger::Field::tString)
                 arr.push_back(f.s);
             else
-                abort();
+                unreachable();
     }
 
     void write(const nlohmann::json & json)

src/libutil/serialise.cc

@@ -260,7 +260,7 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
                 });
             }
 
-            if (!*coro) { abort(); }
+            if (!*coro) { unreachable(); }
 
             if (!cur.empty()) {
                 CoroutineContext ctx;
@@ -271,12 +271,12 @@ std::unique_ptr<FinishSink> sourceToSink(std::function<void(Source &)> fun)
         void finish() override
         {
             if (!coro) return;
-            if (!*coro) abort();
+            if (!*coro) unreachable();
             {
                 CoroutineContext ctx;
                 (*coro)(true);
             }
-            if (*coro) abort();
+            if (*coro) unreachable();
         }
     };
 
@@ -316,7 +316,7 @@ std::unique_ptr<Source> sinkToSource(
                 });
             }
 
-            if (!*coro) { eof(); abort(); }
+            if (!*coro) { eof(); unreachable(); }
 
             if (pos == cur.size()) {
                 if (!cur.empty()) {

src/libutil/sync.hh

@@ -7,6 +7,8 @@
 #include <condition_variable>
 #include <cassert>
 
+#include "error.hh"
+
 namespace nix {
 
 /**
@@ -47,7 +49,7 @@ public:
         friend SyncBase;
         Lock(SyncBase * s) : s(s), lk(s->mutex) { }
     public:
-        Lock(Lock && l) : s(l.s) { abort(); }
+        Lock(Lock && l) : s(l.s) { unreachable(); }
         Lock(const Lock & l) = delete;
         ~Lock() { }
 

src/libutil/unix/monitor-fd.hh

@@ -40,7 +40,9 @@ public:
                     #endif
                     ;
                 auto count = poll(fds, 1, -1);
-                if (count == -1) abort(); // can't happen
+                if (count == -1)
+                    unreachable();
+
                 /* This shouldn't happen, but can on macOS due to a bug.
                    See rdar://37550628.
 

src/libutil/unix/processes.cc

@@ -182,7 +182,7 @@ static pid_t doFork(bool allowVfork, ChildWrapperFunction & fun)
 #endif
     if (pid != 0) return pid;
     fun();
-    abort();
+    unreachable();
 }
 
 

src/nix-env/nix-env.cc

@@ -1159,7 +1159,7 @@ static void opQuery(Globals & globals, Strings opFlags, Strings opArgs)
                     case cvEqual: ch = '='; break;
                     case cvGreater: ch = '<'; break;
                     case cvUnavail: ch = '-'; break;
-                    default: abort();
+                    default: unreachable();
                 }
 
                 if (xmlOutput) {

src/nix-store/nix-store.cc

@@ -480,7 +480,7 @@ static void opQuery(Strings opFlags, Strings opArgs)
         }
 
         default:
-            abort();
+            unreachable();
     }
 }
 

tests/functional/repl.sh

@@ -262,6 +262,23 @@ badExitCode=0
 
 nixVersion="$(nix eval --impure --raw --expr 'builtins.nixVersion' --extra-experimental-features nix-command)"
 
+# TODO: write a repl interacter for testing. Papering over the differences between readline / editline and between platforms is a pain.
+
+# I couldn't get readline and editline to agree on the newline before the prompt,
+# so let's just force it to be one empty line.
+stripEmptyLinesBeforePrompt() {
+  # --null-data:  treat input as NUL-terminated instead of newline-terminated
+  sed --null-data 's/\n\n*nix-repl>/\n\nnix-repl>/g'
+}
+
+# We don't get a final prompt on darwin, so we strip this as well.
+stripFinalPrompt() {
+  # Strip the final prompt and/or any trailing spaces
+  sed --null-data \
+    -e 's/\(.*[^\n]\)\n\n*nix-repl>[ \n]*$/\1/' \
+    -e 's/[ \n]*$/\n/'
+}
+
 runRepl () {
 
   # That is right, we are also filtering out the testdir _without underscores_.
@@ -273,8 +290,13 @@ runRepl () {
   testDirNoUnderscores="${testDir//_/}"
 
   # TODO: pass arguments to nix repl; see lang.sh
+  _NIX_TEST_RAW_MARKDOWN=1 \
+  _NIX_TEST_REPL_ECHO=1 \
   nix repl 2>&1 \
     | stripColors \
+    | tr -d '\0' \
+    | stripEmptyLinesBeforePrompt \
+    | stripFinalPrompt \
     | sed \
       -e "s@$testDir@/path/to/tests/functional@g" \
       -e "s@$testDirNoUnderscores@/path/to/tests/functional@g" \
@@ -289,7 +311,10 @@ for test in $(cd "$testDir/repl"; echo *.in); do
     in="$testDir/repl/$test.in"
     actual="$testDir/repl/$test.actual"
     expected="$testDir/repl/$test.expected"
-    (cd "$testDir/repl"; set +x; runRepl 2>&1) < "$in" > "$actual"
+    (cd "$testDir/repl"; set +x; runRepl 2>&1) < "$in" > "$actual" || {
+        echo "FAIL: $test (exit code $?)" >&2
+        badExitCode=1
+    }
     diffAndAcceptInner "$test" "$actual" "$expected"
 done
 

tests/functional/repl/doc-comment-curried-args.expected

@@ -1,24 +1,28 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function curriedArgs
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:48:5
+nix-repl> :doc curriedArgs
+Function `curriedArgs`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:48:5
 
-    A documented function.
+A documented function.
 
+nix-repl> x = curriedArgs 1        
 
+nix-repl> "Note that users may not expect this to behave as it currently does"
 "Note that users may not expect this to behave as it currently does"
 
-Function curriedArgs
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:50:5
+nix-repl> :doc x
+Function `curriedArgs`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:50:5
 
-    The function returned by applying once
+The function returned by applying once
 
-"This won't produce documentation, because we can't actually document arbitrary values"
+nix-repl> "This won't produce docs; no support for arbitrary values"
+"This won't produce docs; no support for arbitrary values"
 
+nix-repl> :doc x 2
 error: value does not have documentation
-
-

tests/functional/repl/doc-comment-curried-args.in

@@ -3,5 +3,5 @@
 x = curriedArgs 1        
 "Note that users may not expect this to behave as it currently does"
 :doc x
-"This won't produce documentation, because we can't actually document arbitrary values"
+"This won't produce docs; no support for arbitrary values"
 :doc x 2

tests/functional/repl/doc-comment-formals.expected

@@ -1,13 +1,14 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
+nix-repl> "Note that this is not yet complete"
 "Note that this is not yet complete"
 
-Function documentedFormals
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:57:5
-
-    Finds x
-
+nix-repl> :doc documentedFormals
+Function `documentedFormals`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:57:5
 
+Finds x

tests/functional/repl/doc-comment-function.expected

@@ -1,8 +1,7 @@
 Nix <nix version>
 Type :? for help.
-Function defined at
-    /path/to/tests/functional/repl/doc-comment-function.nix:2:1
-
-    A doc comment for a file that only contains a function
 
+nix-repl> :doc import ./doc-comment-function.nix
+Function defined at /path/to/tests/functional/repl/doc-comment-function.nix:2:1
 
+A doc comment for a file that only contains a function

tests/functional/repl/doc-compact.expected

@@ -1,11 +1,11 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function compact
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:18:20
-
-    boom
-
+nix-repl> :doc compact
+Function `compact`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:18:20
 
+boom

tests/functional/repl/doc-constant.expected

@@ -1,23 +1,27 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
+nix-repl> :doc constant
 error: value does not have documentation
 
-Attribute version
+nix-repl> :doc lib.version
+Attribute `version`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:30:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:30:3
 
-    Immovably fixed.
+Immovably fixed.
 
-Attribute empty
+nix-repl> :doc lib.attr.empty
+Attribute `empty`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:33:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:33:3
 
-    Unchangeably constant.
+Unchangeably constant.
 
+nix-repl> :doc lib.attr.undocument
 error:
        … while evaluating the attribute 'attr.undocument'
          at /path/to/tests/functional/repl/doc-comments.nix:33:3:
@@ -32,59 +36,65 @@ error:
              | ^
        Did you mean undocumented?
 
-Attribute constant
+nix-repl> :doc (import ./doc-comments.nix).constant
+Attribute `constant`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:27:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:27:3
 
-    Firmly rigid.
+Firmly rigid.
 
-Attribute version
+nix-repl> :doc (import ./doc-comments.nix).lib.version
+Attribute `version`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:30:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:30:3
 
-    Immovably fixed.
+Immovably fixed.
 
-Attribute empty
+nix-repl> :doc (import ./doc-comments.nix).lib.attr.empty
+Attribute `empty`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:33:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:33:3
 
-    Unchangeably constant.
+Unchangeably constant.
 
-Attribute undocumented
+nix-repl> :doc (import ./doc-comments.nix).lib.attr.undocumented
+Attribute `undocumented`
 
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:35:3
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:35:3
 
-    No documentation found.
+No documentation found.
 
+nix-repl> :doc missing
 error: undefined variable 'missing'
        at «string»:1:1:
             1| missing
              | ^
 
+nix-repl> :doc constanz
 error: undefined variable 'constanz'
        at «string»:1:1:
             1| constanz
              | ^
 
+nix-repl> :doc missing.attr
 error: undefined variable 'missing'
        at «string»:1:1:
             1| missing.attr
              | ^
 
+nix-repl> :doc lib.missing
 error: attribute 'missing' missing
        at «string»:1:1:
             1| lib.missing
              | ^
 
+nix-repl> :doc lib.missing.attr
 error: attribute 'missing' missing
        at «string»:1:1:
             1| lib.missing.attr
              | ^
 
+nix-repl> :doc lib.attr.undocumental
 error:
        … while evaluating the attribute 'attr.undocumental'
          at /path/to/tests/functional/repl/doc-comments.nix:33:3:
@@ -98,5 +108,3 @@ error:
             1| lib.attr.undocumental
              | ^
        Did you mean undocumented?
-
-

tests/functional/repl/doc-floatedIn.expected

@@ -1,11 +1,11 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function floatedIn
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:16:5
-
-    This also works.
-
+nix-repl> :doc floatedIn
+Function `floatedIn`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:16:5
 
+This also works.

tests/functional/repl/doc-lambda-flavors.expected

@@ -1,29 +1,29 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function nonStrict
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:37:70
+nix-repl> :doc nonStrict
+Function `nonStrict`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:37:70
 
-    My syntax is not strict, but I'm strict anyway.
+My syntax is not strict, but I'm strict anyway.
 
-Function strict
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:38:63
+nix-repl> :doc strict
+Function `strict`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:38:63
 
-    I don't have to be strict, but I am anyway.
+I don't have to be strict, but I am anyway.
 
-Function strictPre
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:40:48
+nix-repl> :doc strictPre
+Function `strictPre`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:40:48
 
-    Here's one way to do this
-
-Function strictPost
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:41:53
-
-    Here's another way to do this
+Here's one way to do this
 
+nix-repl> :doc strictPost
+Function `strictPost`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:41:53
 
+Here's another way to do this

tests/functional/repl/doc-measurement.expected

@@ -1,11 +1,11 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function measurement
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:13:17
-
-    👈 precisely this wide 👉
-
+nix-repl> :doc measurement
+Function `measurement`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:13:17
 
+👈 precisely this wide 👉

tests/functional/repl/doc-multiply.expected

@@ -1,15 +1,17 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function multiply
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:10:14
-
-    Perform arithmetic multiplication. It's kind of like
-    repeated addition, very neat.
-
-      | multiply 2 3
-      | => 6
+nix-repl> :doc multiply
+Function `multiply`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:10:14
 
 
+Perform *arithmetic* multiplication. It's kind of like repeated **addition**, very neat.
+
+```nix
+multiply 2 3
+=> 6
+```

tests/functional/repl/doc-unambiguous.expected

@@ -1,11 +1,11 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l doc-comments.nix
 Added <number omitted> variables.
 
-Function unambiguous
-    … defined at
-    /path/to/tests/functional/repl/doc-comments.nix:24:5
-
-    Very close
-
+nix-repl> :doc unambiguous
+Function `unambiguous`\
+  … defined at /path/to/tests/functional/repl/doc-comments.nix:24:5
 
+Very close

tests/functional/repl/pretty-print-idempotent.expected

@@ -1,29 +1,37 @@
 Nix <nix version>
 Type :? for help.
+
+nix-repl> :l pretty-print-idempotent.nix
 Added <number omitted> variables.
 
+nix-repl> oneDeep
 { homepage = "https://example.com"; }
 
+nix-repl> oneDeep
 { homepage = "https://example.com"; }
 
+nix-repl> twoDeep
 {
   layerOne = { ... };
 }
 
+nix-repl> twoDeep
 {
   layerOne = { ... };
 }
 
+nix-repl> oneDeepList
 [ "https://example.com" ]
 
+nix-repl> oneDeepList
 [ "https://example.com" ]
 
+nix-repl> twoDeepList
 [
   [ ... ]
 ]
 
+nix-repl> twoDeepList
 [
   [ ... ]
 ]
-
-