Merge remote-tracking branch 'origin/eval-suggestions'

2 files changed, 48 insertions, 5 deletions

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 0207603c3..c65ef9738 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -729,9 +729,18 @@ LocalNoInlineNoReturn(void throwEvalError(const char * s, const std::string & s2
     throw EvalError(s, s2);
 }
 
+LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const Suggestions & suggestions, const char * s, const std::string & s2))
+{
+    throw EvalError(ErrorInfo {
+        .msg = hintfmt(s, s2),
+        .errPos = pos,
+        .suggestions = suggestions,
+    });
+}
+
 LocalNoInlineNoReturn(void throwEvalError(const Pos & pos, const char * s, const std::string & s2))
 {
-    throw EvalError({
+    throw EvalError(ErrorInfo {
         .msg = hintfmt(s, s2),
         .errPos = pos
     });
@@ -775,6 +784,16 @@ LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const char * s, const
     });
 }
 
+LocalNoInlineNoReturn(void throwTypeError(const Pos & pos, const Suggestions & suggestions, const char * s, const ExprLambda & fun, const Symbol & s2))
+{
+    throw TypeError(ErrorInfo {
+        .msg = hintfmt(s, fun.showNamePos(), s2),
+        .errPos = pos,
+        .suggestions = suggestions,
+    });
+}
+
+
 LocalNoInlineNoReturn(void throwTypeError(const char * s, const Value & v))
 {
     throw TypeError(s, showType(v));
@@ -1247,8 +1266,15 @@ void ExprSelect::eval(EvalState & state, Env & env, Value & v)
                 }
             } else {
                 state.forceAttrs(*vAttrs, pos);
-                if ((j = vAttrs->attrs->find(name)) == vAttrs->attrs->end())
-                    throwEvalError(pos, "attribute '%1%' missing", name);
+                if ((j = vAttrs->attrs->find(name)) == vAttrs->attrs->end()) {
+                    std::set<std::string> allAttrNames;
+                    for (auto & attr : *vAttrs->attrs)
+                        allAttrNames.insert(attr.name);
+                    throwEvalError(
+                        pos,
+                        Suggestions::bestMatches(allAttrNames, name),
+                        "attribute '%1%' missing", name);
+                }
             }
             vAttrs = j->value;
             pos2 = j->pos;
@@ -1364,8 +1390,17 @@ void EvalState::callFunction(Value & fun, size_t nrArgs, Value * * args, Value &
                     /* Nope, so show the first unexpected argument to the
                        user. */
                     for (auto & i : *args[0]->attrs)
-                        if (!lambda.formals->has(i.name))
-                            throwTypeError(pos, "%1% called with unexpected argument '%2%'", lambda, i.name);
+                        if (!lambda.formals->has(i.name)) {
+                            std::set<std::string> formalNames;
+                            for (auto & formal : lambda.formals->formals)
+                                formalNames.insert(formal.name);
+                            throwTypeError(
+                                pos,
+                                Suggestions::bestMatches(formalNames, i.name),
+                                "%1% called with unexpected argument '%2%'",
+                                lambda,
+                                i.name);
+                        }
                     abort(); // can't happen
                 }
             }
diff --git a/tests/suggestions.sh b/tests/suggestions.sh
index 16a5a7004..f18fefef9 100644
--- a/tests/suggestions.sh
+++ b/tests/suggestions.sh
@@ -34,3 +34,11 @@ NIX_BUILD_STDERR_WITH_SUGGESTIONS=$(! nix build .\#fob 2>&1 1>/dev/null)
 NIX_BUILD_STDERR_WITH_NO_CLOSE_SUGGESTION=$(! nix build .\#bar 2>&1 1>/dev/null)
 [[ ! "$NIX_BUILD_STDERR_WITH_NO_CLOSE_SUGGESTION" =~ "Did you mean" ]] || \
     fail "The nix build stderr shouldn’t suggest anything if there’s nothing relevant to suggest"
+
+NIX_EVAL_STDERR_WITH_SUGGESTIONS=$(! nix build --impure --expr '(builtins.getFlake (builtins.toPath ./.)).packages.'$system'.fob' 2>&1 1>/dev/null)
+[[ "$NIX_EVAL_STDERR_WITH_SUGGESTIONS" =~ "Did you mean one of fo1, fo2, foo or fooo?" ]] || \
+    fail "The evaluator should suggest the three closest possiblities"
+
+NIX_EVAL_STDERR_WITH_SUGGESTIONS=$(! nix build --impure --expr '({ foo }: foo) { foo = 1; fob = 2; }' 2>&1 1>/dev/null)
+[[ "$NIX_EVAL_STDERR_WITH_SUGGESTIONS" =~ "Did you mean foo?" ]] || \
+    fail "The evaluator should suggest the three closest possiblities"