Backport SourcePath from the lazy-trees branch

This introduces the SourcePath type from lazy-trees as an abstraction
for accessing files from inputs that may not be materialized in the
real filesystem (e.g. Git repositories). Currently, however, it's just
a wrapper around CanonPath, so it shouldn't change any behaviour. (On
lazy-trees, SourcePath is a <InputAccessor, CanonPath> tuple.)

1 files changed, 6 insertions, 4 deletions

diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index 1219b2471..ec4ad2f5e 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -442,8 +442,10 @@ Value & AttrCursor::forceValue()
         if (v.type() == nString)
             cachedValue = {root->db->setString(getKey(), v.string.s, v.string.context),
                            string_t{v.string.s, {}}};
-        else if (v.type() == nPath)
-            cachedValue = {root->db->setString(getKey(), v.path), string_t{v.path, {}}};
+        else if (v.type() == nPath) {
+            auto path = v.path().path;
+            cachedValue = {root->db->setString(getKey(), path.abs()), string_t{path.abs(), {}}};
+        }
         else if (v.type() == nBool)
             cachedValue = {root->db->setBool(getKey(), v.boolean), v.boolean};
         else if (v.type() == nInt)
@@ -580,7 +582,7 @@ std::string AttrCursor::getString()
     if (v.type() != nString && v.type() != nPath)
         root->state.error("'%s' is not a string but %s", getAttrPathStr()).debugThrow<TypeError>();
 
-    return v.type() == nString ? v.string.s : v.path;
+    return v.type() == nString ? v.string.s : v.path().to_string();
 }
 
 string_t AttrCursor::getStringWithContext()
@@ -622,7 +624,7 @@ string_t AttrCursor::getStringWithContext()
     if (v.type() == nString)
         return {v.string.s, v.getContext(*root->state.store)};
     else if (v.type() == nPath)
-        return {v.path, {}};
+        return {v.path().to_string(), {}};
     else
         root->state.error("'%s' is not a string but %s", getAttrPathStr()).debugThrow<TypeError>();
 }