Fix nix shebang interaction with #8131 overhaul completions

src/libcmd/installables.cc

@@ -294,7 +294,9 @@ void completeFlakeRefWithFragment(
                 prefixRoot = ".";
             }
             auto flakeRefS = std::string(prefix.substr(0, hash));
-            auto flakeRef = parseFlakeRef(expandTilde(flakeRefS), absPath(getCommandBaseDir()));
+
+            // TODO: ideally this would use the command base directory instead of assuming ".".
+            auto flakeRef = parseFlakeRef(expandTilde(flakeRefS), absPath("."));
 
             auto evalCache = openEvalCache(*evalState,
                 std::make_shared<flake::LockedFlake>(lockFlake(*evalState, flakeRef, lockFlags)));

src/libutil/args.cc

@@ -80,12 +80,6 @@ std::optional<std::string> RootArgs::needsCompletion(std::string_view s)
     return {};
 }
 
-void RootArgs::parseCmdline(const Strings & _cmdline)
-{
-    // Default via 5.1.2.2.1 in C standard
-    Args::parseCmdline(_cmdline, false);
-}
-
 /**
  * Basically this is `typedef std::optional<Parser> Parser(std::string_view s, Strings & r);`
  *
@@ -227,7 +221,7 @@ static Strings parseShebangContent(std::string_view s) {
     return result;
 }
 
-void Args::parseCmdline(const Strings & _cmdline, bool allowShebang)
+void RootArgs::parseCmdline(const Strings & _cmdline, bool allowShebang)
 {
     Strings pendingArgs;
     bool dashDash = false;
@@ -339,10 +333,13 @@ void Args::parseCmdline(const Strings & _cmdline, bool allowShebang)
 
 Path Args::getCommandBaseDir() const
 {
-    if (parent)
-        return parent->getCommandBaseDir();
-    else
-        return commandBaseDir;
+    assert(parent);
+    return parent->getCommandBaseDir();
+}
+
+Path RootArgs::getCommandBaseDir() const
+{
+    return commandBaseDir;
 }
 
 bool Args::processFlag(Strings::iterator & pos, Strings::iterator end)

src/libutil/args.hh

@@ -24,24 +24,9 @@ class AddCompletions;
 
 class Args
 {
-    /**
-     * @brief The command's "working directory", but only set when top level.
-     *
-     * Use getCommandBaseDir() to get the directory regardless of whether this
-     * is a top-level command or subcommand.
-     *
-     * @see getCommandBaseDir()
-     */
-    Path commandBaseDir = ".";
 
 public:
 
-    /**
-     * Parse the command line with argv0, throwing a UsageError if something
-       goes wrong.
-     */
-    void parseCmdline(const Strings & _cmdline, bool allowShebang);
-
     /**
      * Return a short one-line description of the command.
     */
@@ -62,7 +47,7 @@ public:
      *
      * This only returns the correct value after parseCmdline() has run.
      */
-    Path getCommandBaseDir() const;
+    virtual Path getCommandBaseDir() const;
 
 protected:
 

src/libutil/args/root.hh

@@ -29,14 +29,26 @@ struct Completions final : AddCompletions
  */
 class RootArgs : virtual public Args
 {
+    /**
+     * @brief The command's "working directory", but only set when top level.
+     *
+     * Use getCommandBaseDir() to get the directory regardless of whether this
+     * is a top-level command or subcommand.
+     *
+     * @see getCommandBaseDir()
+     */
+    Path commandBaseDir = ".";
+
 public:
     /** Parse the command line, throwing a UsageError if something goes
      * wrong.
      */
-    void parseCmdline(const Strings & cmdline);
+    void parseCmdline(const Strings & cmdline, bool allowShebang = false);
 
     std::shared_ptr<Completions> completions;
 
+    Path getCommandBaseDir() const override;
+
 protected:
 
     friend class Args;