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

6 files changed, 12 insertions, 95 deletions

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index debeaf75f..8e3077a67 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -14,6 +14,7 @@
 #include "profiles.hh"
 #include "print.hh"
 #include "gc-small-vector.hh"
+#include "fetch-to-store.hh"
 
 #include <algorithm>
 #include <chrono>
@@ -879,7 +880,7 @@ void EvalState::runDebugRepl(const Error * error, const Env & env, const Expr &
         ? std::make_unique<DebugTraceStacker>(
             *this,
             DebugTrace {
-                .pos = error->info().errPos ? error->info().errPos : static_cast<std::shared_ptr<AbstractPos>>(positions[expr.getPos()]),
+                .pos = error->info().errPos ? error->info().errPos : positions[expr.getPos()],
                 .expr = expr,
                 .env = env,
                 .hint = error->info().msg,
@@ -916,7 +917,7 @@ static std::unique_ptr<DebugTraceStacker> makeDebugTraceStacker(
     EvalState & state,
     Expr & expr,
     Env & env,
-    std::shared_ptr<AbstractPos> && pos,
+    std::shared_ptr<Pos> && pos,
     const char * s,
     const std::string & s2)
 {
@@ -1214,7 +1215,7 @@ void EvalState::cacheFile(
                 *this,
                 *e,
                 this->baseEnv,
-                e->getPos() ? static_cast<std::shared_ptr<AbstractPos>>(positions[e->getPos()]) : nullptr,
+                e->getPos() ? std::make_shared<Pos>(positions[e->getPos()]) : nullptr,
                 "while evaluating the file '%1%':", resolvedPath.to_string())
             : nullptr;
 
@@ -2388,7 +2389,7 @@ StorePath EvalState::copyPathToStore(NixStringContext & context, const SourcePat
     auto dstPath = i != srcToStore.end()
         ? i->second
         : [&]() {
-            auto dstPath = path.fetchToStore(store, path.baseName(), nullptr, repair);
+            auto dstPath = fetchToStore(*store, path, path.baseName(), FileIngestionMethod::Recursive, nullptr, repair);
             allowPath(dstPath);
             srcToStore.insert_or_assign(path, dstPath);
             printMsg(lvlChatty, "copied source '%1%' -> '%2%'", path, store->printStorePath(dstPath));
diff --git a/src/libexpr/eval.hh b/src/libexpr/eval.hh
index 9cf50ba6c..d070fdab8 100644
--- a/src/libexpr/eval.hh
+++ b/src/libexpr/eval.hh
@@ -141,7 +141,7 @@ struct RegexCache;
 std::shared_ptr<RegexCache> makeRegexCache();
 
 struct DebugTrace {
-    std::shared_ptr<AbstractPos> pos;
+    std::shared_ptr<Pos> pos;
     const Expr & expr;
     const Env & env;
     hintformat hint;
diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index b34112be1..eb5d0d3d4 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -11,58 +11,6 @@ namespace nix {
 
 ExprBlackHole eBlackHole;
 
-struct PosAdapter : AbstractPos
-{
-    Pos::Origin origin;
-
-    PosAdapter(Pos::Origin origin)
-        : origin(std::move(origin))
-    {
-    }
-
-    std::optional<std::string> getSource() const override
-    {
-        return std::visit(overloaded {
-            [](const Pos::none_tag &) -> std::optional<std::string> {
-                return std::nullopt;
-            },
-            [](const Pos::Stdin & s) -> std::optional<std::string> {
-                // Get rid of the null terminators added by the parser.
-                return std::string(s.source->c_str());
-            },
-            [](const Pos::String & s) -> std::optional<std::string> {
-                // Get rid of the null terminators added by the parser.
-                return std::string(s.source->c_str());
-            },
-            [](const SourcePath & path) -> std::optional<std::string> {
-                try {
-                    return path.readFile();
-                } catch (Error &) {
-                    return std::nullopt;
-                }
-            }
-        }, origin);
-    }
-
-    void print(std::ostream & out) const override
-    {
-        std::visit(overloaded {
-            [&](const Pos::none_tag &) { out << "«none»"; },
-            [&](const Pos::Stdin &) { out << "«stdin»"; },
-            [&](const Pos::String & s) { out << "«string»"; },
-            [&](const SourcePath & path) { out << path; }
-        }, origin);
-    }
-};
-
-Pos::operator std::shared_ptr<AbstractPos>() const
-{
-    auto pos = std::make_shared<PosAdapter>(origin);
-    pos->line = line;
-    pos->column = column;
-    return pos;
-}
-
 // FIXME: remove, because *symbols* are abstract and do not have a single
 //        textual representation; see printIdentifier()
 std::ostream & operator <<(std::ostream & str, const SymbolStr & symbol)
@@ -268,17 +216,6 @@ void ExprPos::show(const SymbolTable & symbols, std::ostream & str) const
 }
 
 
-std::ostream & operator << (std::ostream & str, const Pos & pos)
-{
-    if (auto pos2 = (std::shared_ptr<AbstractPos>) pos) {
-        str << *pos2;
-    } else
-        str << "undefined position";
-
-    return str;
-}
-
-
 std::string showAttrPath(const SymbolTable & symbols, const AttrPath & attrPath)
 {
     std::ostringstream out;
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index b38f19b41..6f2a4c0f9 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -8,6 +8,7 @@
 #include "symbol-table.hh"
 #include "error.hh"
 #include "chunked-vector.hh"
+#include "position.hh"
 
 namespace nix {
 
@@ -29,27 +30,6 @@ public:
     using EvalError::EvalError;
 };
 
-/**
- * Position objects.
- */
-struct Pos
-{
-    uint32_t line;
-    uint32_t column;
-
-    struct none_tag { };
-    struct Stdin { ref<std::string> source; };
-    struct String { ref<std::string> source; };
-
-    typedef std::variant<none_tag, Stdin, String, SourcePath> Origin;
-
-    Origin origin;
-
-    explicit operator bool() const { return line > 0; }
-
-    operator std::shared_ptr<AbstractPos>() const;
-};
-
 class PosIdx {
     friend class PosTable;
 
@@ -82,7 +62,7 @@ public:
         mutable uint32_t idx = std::numeric_limits<uint32_t>::max();
 
         // Used for searching in PosTable::[].
-        explicit Origin(uint32_t idx): idx(idx), origin{Pos::none_tag()} {}
+        explicit Origin(uint32_t idx): idx(idx), origin{std::monostate()} {}
 
     public:
         const Pos::Origin origin;
@@ -133,8 +113,6 @@ public:
 
 inline PosIdx noPos = {};
 
-std::ostream & operator << (std::ostream & str, const Pos & pos);
-
 
 struct Env;
 struct Value;
diff --git a/src/libexpr/primops.cc b/src/libexpr/primops.cc
index d64f2d51e..1a961582f 100644
--- a/src/libexpr/primops.cc
+++ b/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);
diff --git a/src/libexpr/value.hh b/src/libexpr/value.hh
index 224ffac9c..f90082e61 100644
--- a/src/libexpr/value.hh
+++ b/src/libexpr/value.hh
@@ -7,6 +7,7 @@
 #include "symbol-table.hh"
 #include "value/context.hh"
 #include "input-accessor.hh"
+#include "source-path.hh"
 
 #if HAVE_BOEHMGC
 #include <gc/gc_allocator.h>