nix flake info: Show flake subdirectory

src/libexpr/flake/flakeref.cc

@@ -16,7 +16,10 @@ const static std::string subDirRegex = subDirElemRegex + "(?:/" + subDirElemRege
 
 std::string FlakeRef::to_string() const
 {
-    return input->to_string();
+    auto url = input->toURL();
+    if (subdir != "")
+        url.query.insert_or_assign("dir", subdir);
+    return url.to_string();
 }
 
 fetchers::Attrs FlakeRef::toAttrs() const

src/libstore/fetchers/fetchers.hh

@@ -5,6 +5,7 @@
 #include "path.hh"
 #include "tree-info.hh"
 #include "attrs.hh"
+#include "parse.hh"
 
 #include <memory>
 
@@ -45,7 +46,12 @@ struct Input : std::enable_shared_from_this<Input>
 
     virtual std::optional<Hash> getRev() const { return {}; }
 
-    virtual std::string to_string() const = 0;
+    virtual ParsedURL toURL() const = 0;
+
+    std::string to_string() const
+    {
+        return toURL().to_string();
+    }
 
     Attrs toAttrs() const;
 
@@ -74,8 +80,6 @@ private:
     virtual Attrs toAttrsInternal() const = 0;
 };
 
-struct ParsedURL;
-
 struct InputScheme
 {
     virtual ~InputScheme() { }

src/libstore/fetchers/git.cc

@@ -48,14 +48,14 @@ struct GitInput : Input
 
     std::optional<Hash> getRev() const override { return rev; }
 
-    std::string to_string() const override
+    ParsedURL toURL() const override
     {
         ParsedURL url2(url);
         if (url2.scheme != "git") url2.scheme = "git+" + url2.scheme;
         if (rev) url2.query.insert_or_assign("rev", rev->gitRev());
         if (ref) url2.query.insert_or_assign("ref", *ref);
         if (shallow) url2.query.insert_or_assign("shallow", "1");
-        return url2.to_string();
+        return url2;
     }
 
     Attrs toAttrsInternal() const override

src/libstore/fetchers/github.cc

@@ -42,13 +42,16 @@ struct GitHubInput : Input
 
     std::optional<Hash> getRev() const override { return rev; }
 
-    std::string to_string() const override
+    ParsedURL toURL() const override
     {
-        auto s = fmt("github:%s/%s", owner, repo);
+        auto path = owner + "/" + repo;
         assert(!(ref && rev));
-        if (ref) s += "/" + *ref;
+        if (ref) path += "/" + *ref;
-        if (rev) s += "/" + rev->to_string(Base16, false);
+        if (rev) path += "/" + rev->to_string(Base16, false);
-        return s;
+        return ParsedURL {
+            .scheme = "github",
+            .path = path,
+        };
     }
 
     Attrs toAttrsInternal() const override

src/libstore/fetchers/indirect.cc

@@ -43,14 +43,14 @@ struct IndirectInput : Input
             && (!rev || rev == other2->rev);
     }
 
-    std::string to_string() const override
+    ParsedURL toURL() const override
     {
         ParsedURL url;
         url.scheme = "flake";
         url.path = id;
         if (ref) { url.path += '/'; url.path += *ref; };
         if (rev) { url.path += '/'; url.path += rev->gitRev(); };
-        return url.to_string();
+        return url;
     }
 
     Attrs toAttrsInternal() const override

src/libstore/fetchers/mercurial.cc

@@ -42,13 +42,13 @@ struct MercurialInput : Input
 
     std::optional<Hash> getRev() const override { return rev; }
 
-    std::string to_string() const override
+    ParsedURL toURL() const override
     {
         ParsedURL url2(url);
         url2.scheme = "hg+" + url2.scheme;
         if (rev) url2.query.insert_or_assign("rev", rev->gitRev());
         if (ref) url2.query.insert_or_assign("ref", *ref);
-        return url2.to_string();
+        return url;
     }
 
     Attrs toAttrsInternal() const override

src/libstore/fetchers/tarball.cc

@@ -190,7 +190,7 @@ struct TarballInput : Input
         return hash || narHash;
     }
 
-    std::string to_string() const override
+    ParsedURL toURL() const override
     {
         auto url2(url);
         // NAR hashes are preferred over file hashes since tar/zip files
@@ -199,7 +199,7 @@ struct TarballInput : Input
             url2.query.insert_or_assign("narHash", narHash->to_string(SRI));
         else if (hash)
             url2.query.insert_or_assign("hash", hash->to_string(SRI));
-        return url2.to_string();
+        return url2;
     }
 
     Attrs toAttrsInternal() const override

src/nix/flake.cc

@@ -79,7 +79,7 @@ struct CmdFlakeList : EvalCommand
 
 static void printFlakeInfo(const Store & store, const Flake & flake)
 {
-    std::cout << fmt("URL:           %s\n", flake.lockedRef.input->to_string());
+    std::cout << fmt("URL:           %s\n", flake.lockedRef.to_string());
     std::cout << fmt("Edition:       %s\n", flake.edition);
     if (flake.description)
         std::cout << fmt("Description:   %s\n", *flake.description);
@@ -99,7 +99,7 @@ static nlohmann::json flakeToJson(const Store & store, const Flake & flake)
     if (flake.description)
         j["description"] = *flake.description;
     j["edition"] = flake.edition;
-    j["url"] = flake.lockedRef.input->to_string();
+    j["url"] = flake.lockedRef.to_string();
     if (auto rev = flake.lockedRef.input->getRev())
         j["revision"] = rev->to_string(Base16, false);
     if (flake.sourceInfo->info.revCount)