Make the Store API more type-safe

Most functions now take a StorePath argument rather than a Path (which
is just an alias for std::string). The StorePath constructor ensures
that the path is syntactically correct (i.e. it looks like
<store-dir>/<base32-hash>-<name>). Similarly, functions like
buildPaths() now take a StorePathWithOutputs, rather than abusing Path
by adding a '!<outputs>' suffix.

Note that the StorePath type is implemented in Rust. This involves
some hackery to allow Rust values to be used directly in C++, via a
helper type whose destructor calls the Rust type's drop()
function. The main issue is the dynamic nature of C++ move semantics:
after we have moved a Rust value, we should not call the drop function
on the original value. So when we move a value, we set the original
value to bitwise zero, and the destructor only calls drop() if the
value is not bitwise zero. This should be sufficient for most types.

Also lots of minor cleanups to the C++ API to make it more modern
(e.g. using std::optional and std::string_view in some places).

1 files changed, 21 insertions, 21 deletions

diff --git a/src/libstore/remote-store.hh b/src/libstore/remote-store.hh
index 728df8b00..f301a97d8 100644
--- a/src/libstore/remote-store.hh
+++ b/src/libstore/remote-store.hh
@@ -35,50 +35,50 @@ public:
 
     /* Implementations of abstract store API methods. */
 
-    bool isValidPathUncached(const Path & path) override;
+    bool isValidPathUncached(const StorePath & path) override;
 
-    PathSet queryValidPaths(const PathSet & paths,
+    StorePathSet queryValidPaths(const StorePathSet & paths,
         SubstituteFlag maybeSubstitute = NoSubstitute) override;
 
-    PathSet queryAllValidPaths() override;
+    StorePathSet queryAllValidPaths() override;
 
-    void queryPathInfoUncached(const Path & path,
+    void queryPathInfoUncached(const StorePath & path,
         Callback<std::shared_ptr<const ValidPathInfo>> callback) noexcept override;
 
-    void queryReferrers(const Path & path, PathSet & referrers) override;
+    void queryReferrers(const StorePath & path, StorePathSet & referrers) override;
 
-    PathSet queryValidDerivers(const Path & path) override;
+    StorePathSet queryValidDerivers(const StorePath & path) override;
 
-    PathSet queryDerivationOutputs(const Path & path) override;
+    StorePathSet queryDerivationOutputs(const StorePath & path) override;
 
-    StringSet queryDerivationOutputNames(const Path & path) override;
+    StringSet queryDerivationOutputNames(const StorePath & path) override;
 
-    Path queryPathFromHashPart(const string & hashPart) override;
+    std::optional<StorePath> queryPathFromHashPart(const std::string & hashPart) override;
 
-    PathSet querySubstitutablePaths(const PathSet & paths) override;
+    StorePathSet querySubstitutablePaths(const StorePathSet & paths) override;
 
-    void querySubstitutablePathInfos(const PathSet & paths,
+    void querySubstitutablePathInfos(const StorePathSet & paths,
         SubstitutablePathInfos & infos) override;
 
     void addToStore(const ValidPathInfo & info, Source & nar,
         RepairFlag repair, CheckSigsFlag checkSigs,
         std::shared_ptr<FSAccessor> accessor) override;
 
-    Path addToStore(const string & name, const Path & srcPath,
+    StorePath addToStore(const string & name, const Path & srcPath,
         bool recursive = true, HashType hashAlgo = htSHA256,
         PathFilter & filter = defaultPathFilter, RepairFlag repair = NoRepair) override;
 
-    Path addTextToStore(const string & name, const string & s,
-        const PathSet & references, RepairFlag repair) override;
+    StorePath addTextToStore(const string & name, const string & s,
+        const StorePathSet & references, RepairFlag repair) override;
 
-    void buildPaths(const PathSet & paths, BuildMode buildMode) override;
+    void buildPaths(const std::vector<StorePathWithOutputs> & paths, BuildMode buildMode) override;
 
-    BuildResult buildDerivation(const Path & drvPath, const BasicDerivation & drv,
+    BuildResult buildDerivation(const StorePath & drvPath, const BasicDerivation & drv,
         BuildMode buildMode) override;
 
-    void ensurePath(const Path & path) override;
+    void ensurePath(const StorePath & path) override;
 
-    void addTempRoot(const Path & path) override;
+    void addTempRoot(const StorePath & path) override;
 
     void addIndirectRoot(const Path & path) override;
 
@@ -92,10 +92,10 @@ public:
 
     bool verifyStore(bool checkContents, RepairFlag repair) override;
 
-    void addSignatures(const Path & storePath, const StringSet & sigs) override;
+    void addSignatures(const StorePath & storePath, const StringSet & sigs) override;
 
-    void queryMissing(const PathSet & targets,
-        PathSet & willBuild, PathSet & willSubstitute, PathSet & unknown,
+    void queryMissing(const std::vector<StorePathWithOutputs> & targets,
+        StorePathSet & willBuild, StorePathSet & willSubstitute, StorePathSet & unknown,
         unsigned long long & downloadSize, unsigned long long & narSize) override;
 
     void connect() override;