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-rw-r--r--doc/manual/src/release-notes/rl-next.md3
-rw-r--r--src/libcmd/installables.cc30
-rw-r--r--src/libexpr/attr-path.cc10
-rw-r--r--src/libexpr/eval-cache.cc35
-rw-r--r--src/libexpr/eval-cache.hh8
-rw-r--r--src/libutil/args.cc9
-rw-r--r--src/libutil/error.cc7
-rw-r--r--src/libutil/error.hh8
-rw-r--r--src/libutil/suggestions.cc114
-rw-r--r--src/libutil/suggestions.hh102
-rw-r--r--src/libutil/tests/suggestions.cc43
-rw-r--r--tests/local.mk5
-rw-r--r--tests/suggestions.sh36
13 files changed, 385 insertions, 25 deletions
diff --git a/doc/manual/src/release-notes/rl-next.md b/doc/manual/src/release-notes/rl-next.md
index 80a20278e..ae37ac3be 100644
--- a/doc/manual/src/release-notes/rl-next.md
+++ b/doc/manual/src/release-notes/rl-next.md
@@ -27,3 +27,6 @@
* Templates can now define a `welcomeText` attribute, which is printed out by
`nix flake {init,new} --template <template>`.
+
+* Nix will now helpfully suggest some valid inputs when the user mistypes
+ something on the command-line
diff --git a/src/libcmd/installables.cc b/src/libcmd/installables.cc
index 3209456bf..03f3bd409 100644
--- a/src/libcmd/installables.cc
+++ b/src/libcmd/installables.cc
@@ -272,9 +272,9 @@ void completeFlakeRefWithFragment(
auto attr = root->findAlongAttrPath(attrPath);
if (!attr) continue;
- for (auto & attr2 : attr->getAttrs()) {
+ for (auto & attr2 : (*attr)->getAttrs()) {
if (hasPrefix(attr2, lastAttr)) {
- auto attrPath2 = attr->getAttrPath(attr2);
+ auto attrPath2 = (*attr)->getAttrPath(attr2);
/* Strip the attrpath prefix. */
attrPath2.erase(attrPath2.begin(), attrPath2.begin() + attrPathPrefix.size());
completions->add(flakeRefS + "#" + concatStringsSep(".", attrPath2));
@@ -568,15 +568,22 @@ std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableF
auto cache = openEvalCache(*state, lockedFlake);
auto root = cache->getRoot();
+ Suggestions suggestions;
+
for (auto & attrPath : getActualAttrPaths()) {
debug("trying flake output attribute '%s'", attrPath);
- auto attr = root->findAlongAttrPath(
+ auto attrOrSuggestions = root->findAlongAttrPath(
parseAttrPath(*state, attrPath),
true
);
- if (!attr) continue;
+ if (!attrOrSuggestions) {
+ suggestions += attrOrSuggestions.getSuggestions();
+ continue;
+ }
+
+ auto attr = *attrOrSuggestions;
if (!attr->isDerivation())
throw Error("flake output attribute '%s' is not a derivation", attrPath);
@@ -591,7 +598,7 @@ std::tuple<std::string, FlakeRef, InstallableValue::DerivationInfo> InstallableF
return {attrPath, lockedFlake->flake.lockedRef, std::move(drvInfo)};
}
- throw Error("flake '%s' does not provide attribute %s",
+ throw Error(suggestions, "flake '%s' does not provide attribute %s",
flakeRef, showAttrPaths(getActualAttrPaths()));
}
@@ -610,17 +617,24 @@ std::pair<Value *, Pos> InstallableFlake::toValue(EvalState & state)
auto emptyArgs = state.allocBindings(0);
+ Suggestions suggestions;
+
for (auto & attrPath : getActualAttrPaths()) {
try {
auto [v, pos] = findAlongAttrPath(state, attrPath, *emptyArgs, *vOutputs);
state.forceValue(*v, pos);
return {v, pos};
} catch (AttrPathNotFound & e) {
+ suggestions += e.info().suggestions;
}
}
- throw Error("flake '%s' does not provide attribute %s",
- flakeRef, showAttrPaths(getActualAttrPaths()));
+ throw Error(
+ suggestions,
+ "flake '%s' does not provide attribute %s",
+ flakeRef,
+ showAttrPaths(getActualAttrPaths())
+ );
}
std::vector<std::pair<std::shared_ptr<eval_cache::AttrCursor>, std::string>>
@@ -635,7 +649,7 @@ InstallableFlake::getCursors(EvalState & state)
for (auto & attrPath : getActualAttrPaths()) {
auto attr = root->findAlongAttrPath(parseAttrPath(state, attrPath));
- if (attr) res.push_back({attr, attrPath});
+ if (attr) res.push_back({*attr, attrPath});
}
return res;
diff --git a/src/libexpr/attr-path.cc b/src/libexpr/attr-path.cc
index eb0e706c7..32deecfae 100644
--- a/src/libexpr/attr-path.cc
+++ b/src/libexpr/attr-path.cc
@@ -74,8 +74,14 @@ std::pair<Value *, Pos> findAlongAttrPath(EvalState & state, const std::string &
throw Error("empty attribute name in selection path '%1%'", attrPath);
Bindings::iterator a = v->attrs->find(state.symbols.create(attr));
- if (a == v->attrs->end())
- throw AttrPathNotFound("attribute '%1%' in selection path '%2%' not found", attr, attrPath);
+ if (a == v->attrs->end()) {
+ std::set<std::string> attrNames;
+ for (auto & attr : *v->attrs)
+ attrNames.insert(attr.name);
+
+ auto suggestions = Suggestions::bestMatches(attrNames, attr);
+ throw AttrPathNotFound(suggestions, "attribute '%1%' in selection path '%2%' not found", attr, attrPath);
+ }
v = &*a->value;
pos = *a->pos;
}
diff --git a/src/libexpr/eval-cache.cc b/src/libexpr/eval-cache.cc
index 00d0749f9..188223957 100644
--- a/src/libexpr/eval-cache.cc
+++ b/src/libexpr/eval-cache.cc
@@ -406,6 +406,16 @@ Value & AttrCursor::forceValue()
return v;
}
+Suggestions AttrCursor::getSuggestionsForAttr(Symbol name)
+{
+ auto attrNames = getAttrs();
+ std::set<std::string> strAttrNames;
+ for (auto & name : attrNames)
+ strAttrNames.insert(std::string(name));
+
+ return Suggestions::bestMatches(strAttrNames, name);
+}
+
std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(Symbol name, bool forceErrors)
{
if (root->db) {
@@ -446,6 +456,11 @@ std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(Symbol name, bool forceErro
return nullptr;
//throw TypeError("'%s' is not an attribute set", getAttrPathStr());
+ for (auto & attr : *v.attrs) {
+ if (root->db)
+ root->db->setPlaceholder({cachedValue->first, attr.name});
+ }
+
auto attr = v.attrs->get(name);
if (!attr) {
@@ -464,7 +479,7 @@ std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(Symbol name, bool forceErro
cachedValue2 = {root->db->setPlaceholder({cachedValue->first, name}), placeholder_t()};
}
- return std::make_shared<AttrCursor>(
+ return make_ref<AttrCursor>(
root, std::make_pair(shared_from_this(), name), attr->value, std::move(cachedValue2));
}
@@ -473,27 +488,31 @@ std::shared_ptr<AttrCursor> AttrCursor::maybeGetAttr(std::string_view name)
return maybeGetAttr(root->state.symbols.create(name));
}
-std::shared_ptr<AttrCursor> AttrCursor::getAttr(Symbol name, bool forceErrors)
+ref<AttrCursor> AttrCursor::getAttr(Symbol name, bool forceErrors)
{
auto p = maybeGetAttr(name, forceErrors);
if (!p)
throw Error("attribute '%s' does not exist", getAttrPathStr(name));
- return p;
+ return ref(p);
}
-std::shared_ptr<AttrCursor> AttrCursor::getAttr(std::string_view name)
+ref<AttrCursor> AttrCursor::getAttr(std::string_view name)
{
return getAttr(root->state.symbols.create(name));
}
-std::shared_ptr<AttrCursor> AttrCursor::findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force)
+OrSuggestions<ref<AttrCursor>> AttrCursor::findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force)
{
auto res = shared_from_this();
for (auto & attr : attrPath) {
- res = res->maybeGetAttr(attr, force);
- if (!res) return {};
+ auto child = res->maybeGetAttr(attr, force);
+ if (!child) {
+ auto suggestions = res->getSuggestionsForAttr(attr);
+ return OrSuggestions<ref<AttrCursor>>::failed(suggestions);
+ }
+ res = child;
}
- return res;
+ return ref(res);
}
std::string AttrCursor::getString()
diff --git a/src/libexpr/eval-cache.hh b/src/libexpr/eval-cache.hh
index 43b34ebcb..40f1d4ffc 100644
--- a/src/libexpr/eval-cache.hh
+++ b/src/libexpr/eval-cache.hh
@@ -94,15 +94,17 @@ public:
std::string getAttrPathStr(Symbol name) const;
+ Suggestions getSuggestionsForAttr(Symbol name);
+
std::shared_ptr<AttrCursor> maybeGetAttr(Symbol name, bool forceErrors = false);
std::shared_ptr<AttrCursor> maybeGetAttr(std::string_view name);
- std::shared_ptr<AttrCursor> getAttr(Symbol name, bool forceErrors = false);
+ ref<AttrCursor> getAttr(Symbol name, bool forceErrors = false);
- std::shared_ptr<AttrCursor> getAttr(std::string_view name);
+ ref<AttrCursor> getAttr(std::string_view name);
- std::shared_ptr<AttrCursor> findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force = false);
+ OrSuggestions<ref<AttrCursor>> findAlongAttrPath(const std::vector<Symbol> & attrPath, bool force = false);
std::string getString();
diff --git a/src/libutil/args.cc b/src/libutil/args.cc
index f970c0e9e..69aa0d094 100644
--- a/src/libutil/args.cc
+++ b/src/libutil/args.cc
@@ -328,8 +328,13 @@ MultiCommand::MultiCommand(const Commands & commands_)
completions->add(name);
}
auto i = commands.find(s);
- if (i == commands.end())
- throw UsageError("'%s' is not a recognised command", s);
+ if (i == commands.end()) {
+ std::set<std::string> commandNames;
+ for (auto & [name, _] : commands)
+ commandNames.insert(name);
+ auto suggestions = Suggestions::bestMatches(commandNames, s);
+ throw UsageError(suggestions, "'%s' is not a recognised command", s);
+ }
command = {s, i->second()};
command->second->parent = this;
}}
diff --git a/src/libutil/error.cc b/src/libutil/error.cc
index dcd2f82a5..b2dfb35b2 100644
--- a/src/libutil/error.cc
+++ b/src/libutil/error.cc
@@ -282,6 +282,13 @@ std::ostream & showErrorInfo(std::ostream & out, const ErrorInfo & einfo, bool s
}
}
+ auto suggestions = einfo.suggestions.trim();
+ if (! suggestions.suggestions.empty()){
+ oss << "Did you mean " <<
+ suggestions.trim() <<
+ "?" << std::endl;
+ }
+
// traces
if (showTrace && !einfo.traces.empty()) {
for (auto iter = einfo.traces.rbegin(); iter != einfo.traces.rend(); ++iter) {
diff --git a/src/libutil/error.hh b/src/libutil/error.hh
index d55e1d701..600e94888 100644
--- a/src/libutil/error.hh
+++ b/src/libutil/error.hh
@@ -1,5 +1,6 @@
#pragma once
+#include "suggestions.hh"
#include "ref.hh"
#include "types.hh"
#include "fmt.hh"
@@ -112,6 +113,8 @@ struct ErrorInfo {
std::optional<ErrPos> errPos;
std::list<Trace> traces;
+ Suggestions suggestions;
+
static std::optional<std::string> programName;
};
@@ -141,6 +144,11 @@ public:
: err { .level = lvlError, .msg = hintfmt(fs, args...) }
{ }
+ template<typename... Args>
+ BaseError(const Suggestions & sug, const Args & ... args)
+ : err { .level = lvlError, .msg = hintfmt(args...), .suggestions = sug }
+ { }
+
BaseError(hintformat hint)
: err { .level = lvlError, .msg = hint }
{ }
diff --git a/src/libutil/suggestions.cc b/src/libutil/suggestions.cc
new file mode 100644
index 000000000..9510a5f0c
--- /dev/null
+++ b/src/libutil/suggestions.cc
@@ -0,0 +1,114 @@
+#include "suggestions.hh"
+#include "ansicolor.hh"
+#include "util.hh"
+#include <algorithm>
+
+namespace nix {
+
+int levenshteinDistance(std::string_view first, std::string_view second)
+{
+ // Implementation borrowed from
+ // https://en.wikipedia.org/wiki/Levenshtein_distance#Iterative_with_two_matrix_rows
+
+ int m = first.size();
+ int n = second.size();
+
+ auto v0 = std::vector<int>(n+1);
+ auto v1 = std::vector<int>(n+1);
+
+ for (auto i = 0; i <= n; i++)
+ v0[i] = i;
+
+ for (auto i = 0; i < m; i++) {
+ v1[0] = i+1;
+
+ for (auto j = 0; j < n; j++) {
+ auto deletionCost = v0[j+1] + 1;
+ auto insertionCost = v1[j] + 1;
+ auto substitutionCost = first[i] == second[j] ? v0[j] : v0[j] + 1;
+ v1[j+1] = std::min({deletionCost, insertionCost, substitutionCost});
+ }
+
+ std::swap(v0, v1);
+ }
+
+ return v0[n];
+}
+
+Suggestions Suggestions::bestMatches (
+ std::set<std::string> allMatches,
+ std::string query)
+{
+ std::set<Suggestion> res;
+ for (const auto & possibleMatch : allMatches) {
+ res.insert(Suggestion {
+ .distance = levenshteinDistance(query, possibleMatch),
+ .suggestion = possibleMatch,
+ });
+ }
+ return Suggestions { res };
+}
+
+Suggestions Suggestions::trim(int limit, int maxDistance) const
+{
+ std::set<Suggestion> res;
+
+ int count = 0;
+
+ for (auto & elt : suggestions) {
+ if (count >= limit || elt.distance > maxDistance)
+ break;
+ count++;
+ res.insert(elt);
+ }
+
+ return Suggestions{res};
+}
+
+std::string Suggestion::to_string() const
+{
+ return ANSI_WARNING + filterANSIEscapes(suggestion) + ANSI_NORMAL;
+}
+
+std::string Suggestions::to_string() const
+{
+ switch (suggestions.size()) {
+ case 0:
+ return "";
+ case 1:
+ return suggestions.begin()->to_string();
+ default: {
+ std::string res = "one of ";
+ auto iter = suggestions.begin();
+ res += iter->to_string(); // Iter can’t be end() because the container isn’t null
+ iter++;
+ auto last = suggestions.end(); last--;
+ for ( ; iter != suggestions.end() ; iter++) {
+ res += (iter == last) ? " or " : ", ";
+ res += iter->to_string();
+ }
+ return res;
+ }
+ }
+}
+
+Suggestions & Suggestions::operator+=(const Suggestions & other)
+{
+ suggestions.insert(
+ other.suggestions.begin(),
+ other.suggestions.end()
+ );
+ return *this;
+}
+
+std::ostream & operator<<(std::ostream & str, const Suggestion & suggestion)
+{
+ return str << suggestion.to_string();
+}
+
+std::ostream & operator<<(std::ostream & str, const Suggestions & suggestions)
+{
+ return str << suggestions.to_string();
+}
+
+}
diff --git a/src/libutil/suggestions.hh b/src/libutil/suggestions.hh
new file mode 100644
index 000000000..d54dd8e31
--- /dev/null
+++ b/src/libutil/suggestions.hh
@@ -0,0 +1,102 @@
+#pragma once
+
+#include "comparator.hh"
+#include "types.hh"
+#include <set>
+
+namespace nix {
+
+int levenshteinDistance(std::string_view first, std::string_view second);
+
+/**
+ * A potential suggestion for the cli interface.
+ */
+class Suggestion {
+public:
+ int distance; // The smaller the better
+ std::string suggestion;
+
+ std::string to_string() const;
+
+ GENERATE_CMP(Suggestion, me->distance, me->suggestion)
+};
+
+class Suggestions {
+public:
+ std::set<Suggestion> suggestions;
+
+ std::string to_string() const;
+
+ Suggestions trim(
+ int limit = 5,
+ int maxDistance = 2
+ ) const;
+
+ static Suggestions bestMatches (
+ std::set<std::string> allMatches,
+ std::string query
+ );
+
+ Suggestions& operator+=(const Suggestions & other);
+};
+
+std::ostream & operator<<(std::ostream & str, const Suggestion &);
+std::ostream & operator<<(std::ostream & str, const Suggestions &);
+
+// Either a value of type `T`, or some suggestions
+template<typename T>
+class OrSuggestions {
+public:
+ using Raw = std::variant<T, Suggestions>;
+
+ Raw raw;
+
+ T* operator ->()
+ {
+ return &**this;
+ }
+
+ T& operator *()
+ {
+ return std::get<T>(raw);
+ }
+
+ operator bool() const noexcept
+ {
+ return std::holds_alternative<T>(raw);
+ }
+
+ OrSuggestions(T t)
+ : raw(t)
+ {
+ }
+
+ OrSuggestions()
+ : raw(Suggestions{})
+ {
+ }
+
+ static OrSuggestions<T> failed(const Suggestions & s)
+ {
+ auto res = OrSuggestions<T>();
+ res.raw = s;
+ return res;
+ }
+
+ static OrSuggestions<T> failed()
+ {
+ return OrSuggestions<T>::failed(Suggestions{});
+ }
+
+ const Suggestions & getSuggestions()
+ {
+ static Suggestions noSuggestions;
+ if (const auto & suggestions = std::get_if<Suggestions>(&raw))
+ return *suggestions;
+ else
+ return noSuggestions;
+ }
+
+};
+
+}
diff --git a/src/libutil/tests/suggestions.cc b/src/libutil/tests/suggestions.cc
new file mode 100644
index 000000000..279994abc
--- /dev/null
+++ b/src/libutil/tests/suggestions.cc
@@ -0,0 +1,43 @@
+#include "suggestions.hh"
+#include <gtest/gtest.h>
+
+namespace nix {
+
+ struct LevenshteinDistanceParam {
+ std::string s1, s2;
+ int distance;
+ };
+
+ class LevenshteinDistanceTest :
+ public testing::TestWithParam<LevenshteinDistanceParam> {
+ };
+
+ TEST_P(LevenshteinDistanceTest, CorrectlyComputed) {
+ auto params = GetParam();
+
+ ASSERT_EQ(levenshteinDistance(params.s1, params.s2), params.distance);
+ ASSERT_EQ(levenshteinDistance(params.s2, params.s1), params.distance);
+ }
+
+ INSTANTIATE_TEST_SUITE_P(LevenshteinDistance, LevenshteinDistanceTest,
+ testing::Values(
+ LevenshteinDistanceParam{"foo", "foo", 0},
+ LevenshteinDistanceParam{"foo", "", 3},
+ LevenshteinDistanceParam{"", "", 0},
+ LevenshteinDistanceParam{"foo", "fo", 1},
+ LevenshteinDistanceParam{"foo", "oo", 1},
+ LevenshteinDistanceParam{"foo", "fao", 1},
+ LevenshteinDistanceParam{"foo", "abc", 3}
+ )
+ );
+
+ TEST(Suggestions, Trim) {
+ auto suggestions = Suggestions::bestMatches({"foooo", "bar", "fo", "gao"}, "foo");
+ auto onlyOne = suggestions.trim(1);
+ ASSERT_EQ(onlyOne.suggestions.size(), 1);
+ ASSERT_TRUE(onlyOne.suggestions.begin()->suggestion == "fo");
+
+ auto closest = suggestions.trim(999, 2);
+ ASSERT_EQ(closest.suggestions.size(), 3);
+ }
+}
diff --git a/tests/local.mk b/tests/local.mk
index c3a6aa1fc..8032fc38a 100644
--- a/tests/local.mk
+++ b/tests/local.mk
@@ -92,8 +92,9 @@ nix_tests = \
bash-profile.sh \
pass-as-file.sh \
describe-stores.sh \
- store-ping.sh \
- nix-profile.sh
+ nix-profile.sh \
+ suggestions.sh \
+ store-ping.sh
ifeq ($(HAVE_LIBCPUID), 1)
nix_tests += compute-levels.sh
diff --git a/tests/suggestions.sh b/tests/suggestions.sh
new file mode 100644
index 000000000..16a5a7004
--- /dev/null
+++ b/tests/suggestions.sh
@@ -0,0 +1,36 @@
+source common.sh
+
+clearStore
+
+cd "$TEST_HOME"
+
+cat <<EOF > flake.nix
+{
+ outputs = a: {
+ packages.$system = {
+ foo = 1;
+ fo1 = 1;
+ fo2 = 1;
+ fooo = 1;
+ foooo = 1;
+ fooooo = 1;
+ fooooo1 = 1;
+ fooooo2 = 1;
+ fooooo3 = 1;
+ fooooo4 = 1;
+ fooooo5 = 1;
+ fooooo6 = 1;
+ };
+ };
+}
+EOF
+
+# Probable typo in the requested attribute path. Suggest some close possibilities
+NIX_BUILD_STDERR_WITH_SUGGESTIONS=$(! nix build .\#fob 2>&1 1>/dev/null)
+[[ "$NIX_BUILD_STDERR_WITH_SUGGESTIONS" =~ "Did you mean one of fo1, fo2, foo or fooo?" ]] || \
+ fail "The nix build stderr should suggest the three closest possiblities"
+
+# None of the possible attributes is close to `bar`, so shouldn’t suggest anything
+NIX_BUILD_STDERR_WITH_NO_CLOSE_SUGGESTION=$(! 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"
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-23 03:08:06 +0000