EvalState::getBuiltins

src/libexpr-test-support/tests/libexpr.hh

@@ -40,6 +40,12 @@ namespace nix {
                 return v;
             }
 
+            Value * maybeThunk(std::string input, bool forceValue = true) {
+                Expr * e = state.parseExprFromString(input, state.rootPath(CanonPath::root));
+                assert(e);
+                return e->maybeThunk(state, state.baseEnv);
+            }
+
             Symbol createSymbol(const char * value) {
                 return state.symbols.create(value);
             }

src/libexpr-tests/eval.cc

@@ -138,4 +138,27 @@ TEST(nix_isAllowedURI, non_scheme_colon) {
     ASSERT_FALSE(isAllowedURI("https://foo/bar:baz", allowed));
 }
 
-} // namespace nix
+class EvalStateTest : public LibExprTest {};
+
+TEST_F(EvalStateTest, getBuiltins_ok) {
+    auto evaled = maybeThunk("builtins");
+    auto & builtins = state.getBuiltins();
+    ASSERT_TRUE(builtins.type() == nAttrs);
+    ASSERT_EQ(evaled, &builtins);
+}
+
+TEST_F(EvalStateTest, getBuiltin_ok) {
+    auto & builtin = state.getBuiltin("toString");
+    ASSERT_TRUE(builtin.type() == nFunction);
+    // FIXME
+    // auto evaled = maybeThunk("builtins.toString");
+    // ASSERT_EQ(evaled, &builtin);
+    auto & builtin2 = state.getBuiltin("true");
+    ASSERT_EQ(state.forceBool(builtin2, noPos, "in unit test"), true);
+}
+
+TEST_F(EvalStateTest, getBuiltin_fail) {
+    ASSERT_THROW(state.getBuiltin("nonexistent"), EvalError);
+}
+
+} // namespace nix

src/libexpr/eval.cc

@@ -448,7 +448,7 @@ void EvalState::addConstant(const std::string & name, Value * v, Constant info)
         /* Install value the base environment. */
         staticBaseEnv->vars.emplace_back(symbols.create(name), baseEnvDispl);
         baseEnv.values[baseEnvDispl++] = v;
-        baseEnv.values[0]->payload.attrs->push_back(Attr(symbols.create(name2), v));
+        getBuiltins().payload.attrs->push_back(Attr(symbols.create(name2), v));
     }
 }
 
@@ -516,16 +516,26 @@ Value * EvalState::addPrimOp(PrimOp && primOp)
     else {
         staticBaseEnv->vars.emplace_back(envName, baseEnvDispl);
         baseEnv.values[baseEnvDispl++] = v;
-        baseEnv.values[0]->payload.attrs->push_back(Attr(symbols.create(primOp.name), v));
+        getBuiltins().payload.attrs->push_back(Attr(symbols.create(primOp.name), v));
     }
 
     return v;
 }
 
 
+Value & EvalState::getBuiltins()
+{
+    return *baseEnv.values[0];
+}
+
+
 Value & EvalState::getBuiltin(const std::string & name)
 {
-    return *baseEnv.values[0]->attrs()->find(symbols.create(name))->value;
+    auto it = getBuiltins().attrs()->get(symbols.create(name));
+    if (it)
+        return *it->value;
+    else
+        error<EvalError>("builtin '%1%' not found", name).debugThrow();
 }
 
 

src/libexpr/eval.hh

@@ -623,8 +623,19 @@ private:
 
 public:
 
+    /**
+     * Retrieve a specific builtin, equivalent to evaluating `builtins.${name}`.
+     * @param name The attribute name of the builtin to retrieve.
+     * @throws EvalError if the builtin does not exist.
+     */
     Value & getBuiltin(const std::string & name);
 
+    /**
+     * Retrieve the `builtins` attrset, equivalent to evaluating the reference `builtins`.
+     * Always returns an attribute set value.
+     */
+    Value & getBuiltins();
+
     struct Doc
     {
         Pos pos;

src/libexpr/primops.cc

@@ -4937,7 +4937,7 @@ void EvalState::createBaseEnv()
 
     /* Now that we've added all primops, sort the `builtins' set,
        because attribute lookups expect it to be sorted. */
-    baseEnv.values[0]->payload.attrs->sort();
+    getBuiltins().payload.attrs->sort();
 
     staticBaseEnv->sort();
 

src/nix/main.cc

@@ -435,7 +435,8 @@ void mainWrapped(int argc, char * * argv)
         evalSettings.pureEval = false;
         EvalState state({}, openStore("dummy://"), fetchSettings, evalSettings);
         auto builtinsJson = nlohmann::json::object();
-        for (auto & builtin : *state.baseEnv.values[0]->attrs()) {
+        for (auto & builtinPtr : state.getBuiltins().attrs()->lexicographicOrder(state.symbols)) {
+            auto & builtin = *builtinPtr;
             auto b = nlohmann::json::object();
             if (!builtin.value->isPrimOp()) continue;
             auto primOp = builtin.value->primOp();