Merge pull request #9634 from 9999years/combine-abstract-pos-and-pos

Combine `AbstractPos`, `PosAdapter`, and `Pos`

(cherry picked from commit 113499d16fc87d53b73fb62fe6242154909756ed)

===

this is a bit cursed because originally it was based on InputAccessor
code that we don't have and moved/patched features we likewise don't
have (fetchToStore caching, all the individual accessors,
ContentAddressMethod). the commit is adjusted accordingly to
match (remove caching, ignore accessors, use FileIngestionMethod).

note that `state.rootPath . CanonPath == abs` and
computeStorePathForPath works relative to cwd, so the slight rewrite in
the moved fetchToStore is legal.

Change-Id: I05fd340c273f0bcc8ffabfebdc4a88b98083bce5

src/libexpr/primops.cc

@@ -14,6 +14,7 @@
 #include "value-to-json.hh"
 #include "value-to-xml.hh"
 #include "primops.hh"
+#include "fetch-to-store.hh"
 
 #include <boost/container/small_vector.hpp>
 #include <nlohmann/json.hpp>
@@ -2235,9 +2236,8 @@ static void addPath(
             });
 
         if (!expectedHash || !state.store->isValidPath(*expectedStorePath)) {
-            StorePath dstPath = settings.readOnlyMode
-                ? state.store->computeStorePathForPath(name, path, method, htSHA256, filter).first
-                : state.store->addToStore(name, path, method, htSHA256, filter, state.repair, refs);
+            auto dstPath = fetchToStore(
+                *state.store, state.rootPath(CanonPath(path)), name, method, &filter, state.repair);
             if (expectedHash && expectedStorePath != dstPath)
                 state.debugThrowLastTrace(Error("store path mismatch in (possibly filtered) path added from '%s'", path));
             state.allowAndSetStorePathString(dstPath, v);