Move uriSchemes to *StoreConfig

It is a property of the configuration of a store --- how a store URL is
parsed into a store config, not a store itself.

Progress towards NixOS#10766

src/libstore/http-binary-cache-store.cc

@@ -14,6 +14,14 @@ struct HttpBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
 
     const std::string name() override { return "HTTP Binary Cache Store"; }
 
+    static std::set<std::string> uriSchemes()
+    {
+        static bool forceHttp = getEnv("_NIX_FORCE_HTTP") == "1";
+        auto ret = std::set<std::string>({"http", "https"});
+        if (forceHttp) ret.insert("file");
+        return ret;
+    }
+
     std::string doc() override
     {
         return
@@ -81,14 +89,6 @@ class HttpBinaryCacheStore : public virtual HttpBinaryCacheStoreConfig, public v
         }
     }
 
-    static std::set<std::string> uriSchemes()
-    {
-        static bool forceHttp = getEnv("_NIX_FORCE_HTTP") == "1";
-        auto ret = std::set<std::string>({"http", "https"});
-        if (forceHttp) ret.insert("file");
-        return ret;
-    }
-
 protected:
 
     void maybeDisable()

src/libstore/legacy-ssh-store.hh

@@ -26,6 +26,8 @@ struct LegacySSHStoreConfig : virtual CommonSSHStoreConfig
 
     const std::string name() override { return "SSH Store"; }
 
+    static std::set<std::string> uriSchemes() { return {"ssh"}; }
+
     std::string doc() override;
 };
 
@@ -46,8 +48,6 @@ struct LegacySSHStore : public virtual LegacySSHStoreConfig, public virtual Stor
 
     SSHMaster master;
 
-    static std::set<std::string> uriSchemes() { return {"ssh"}; }
-
     LegacySSHStore(
         std::string_view scheme,
         std::string_view host,

src/libstore/local-binary-cache-store.cc

@@ -13,6 +13,8 @@ struct LocalBinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
 
     const std::string name() override { return "Local Binary Cache Store"; }
 
+    static std::set<std::string> uriSchemes();
+
     std::string doc() override
     {
         return
@@ -53,8 +55,6 @@ class LocalBinaryCacheStore : public virtual LocalBinaryCacheStoreConfig, public
         return "file://" + binaryCacheDir;
     }
 
-    static std::set<std::string> uriSchemes();
-
 protected:
 
     bool fileExists(const std::string & path) override;
@@ -123,7 +123,7 @@ bool LocalBinaryCacheStore::fileExists(const std::string & path)
     return pathExists(binaryCacheDir + "/" + path);
 }
 
-std::set<std::string> LocalBinaryCacheStore::uriSchemes()
+std::set<std::string> LocalBinaryCacheStoreConfig::uriSchemes()
 {
     if (getEnv("_NIX_FORCE_HTTP") == "1")
         return {};

src/libstore/local-overlay-store.hh

@@ -58,6 +58,11 @@ struct LocalOverlayStoreConfig : virtual LocalStoreConfig
         return ExperimentalFeature::LocalOverlayStore;
     }
 
+    static std::set<std::string> uriSchemes()
+    {
+        return { "local-overlay" };
+    }
+
     std::string doc() override;
 
 protected:
@@ -99,11 +104,6 @@ public:
             throw UsageError("local-overlay:// store url doesn't support path part, only scheme and query params");
     }
 
-    static std::set<std::string> uriSchemes()
-    {
-        return { "local-overlay" };
-    }
-
     std::string getUri() override
     {
         return "local-overlay://";

src/libstore/local-store.hh

@@ -62,6 +62,9 @@ struct LocalStoreConfig : virtual LocalFSStoreConfig
 
     const std::string name() override { return "Local Store"; }
 
+    static std::set<std::string> uriSchemes()
+    { return {"local"}; }
+
     std::string doc() override;
 };
 
@@ -144,9 +147,6 @@ public:
 
     ~LocalStore();
 
-    static std::set<std::string> uriSchemes()
-    { return {"local"}; }
-
     /**
      * Implementations of abstract store API methods.
      */

src/libstore/s3-binary-cache-store.cc

@@ -253,6 +253,8 @@ struct S3BinaryCacheStoreConfig : virtual BinaryCacheStoreConfig
 
     const std::string name() override { return "S3 Binary Cache Store"; }
 
+    static std::set<std::string> uriSchemes() { return {"s3"}; }
+
     std::string doc() override
     {
         return
@@ -521,9 +523,6 @@ struct S3BinaryCacheStoreImpl : virtual S3BinaryCacheStoreConfig, public virtual
     {
         return std::nullopt;
     }
-
-    static std::set<std::string> uriSchemes() { return {"s3"}; }
-
 };
 
 static RegisterStoreImplementation<S3BinaryCacheStoreImpl, S3BinaryCacheStoreConfig> regS3BinaryCacheStore;

src/libstore/ssh-store.cc

@@ -112,6 +112,11 @@ struct MountedSSHStoreConfig : virtual SSHStoreConfig, virtual LocalFSStoreConfi
 
     const std::string name() override { return "Experimental SSH Store with filesystem mounted"; }
 
+    static std::set<std::string> uriSchemes()
+    {
+        return {"mounted-ssh-ng"};
+    }
+
     std::string doc() override
     {
         return
@@ -163,11 +168,6 @@ class MountedSSHStore : public virtual MountedSSHStoreConfig, public virtual SSH
         };
     }
 
-    static std::set<std::string> uriSchemes()
-    {
-        return {"mounted-ssh-ng"};
-    }
-
     std::string getUri() override
     {
         return *uriSchemes().begin() + "://" + host;

src/libstore/uds-remote-store.hh

@@ -35,11 +35,12 @@ struct UDSRemoteStoreConfig : virtual LocalFSStoreConfig, virtual RemoteStoreCon
      */
     std::optional<std::string> path;
 
-    static std::set<std::string> uriSchemes()
-    { return {scheme}; }
-
 protected:
     static constexpr char const * scheme = "unix";
+
+public:
+    static std::set<std::string> uriSchemes()
+    { return {scheme}; }
 };
 
 class UDSRemoteStore : public virtual UDSRemoteStoreConfig