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parser-state: fix attribute merging
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@rhendric
rhendric committed Aug 20, 2024
1 parent 4956e7c commit 85b7453
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Showing 4 changed files with 114 additions and 52 deletions.
108 changes: 64 additions & 44 deletions src/libexpr/parser-state.hh
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Original file line number Diff line number Diff line change
Expand Up @@ -88,6 +88,7 @@ struct ParserState
void dupAttr(const AttrPath & attrPath, const PosIdx pos, const PosIdx prevPos);
void dupAttr(Symbol attr, const PosIdx pos, const PosIdx prevPos);
void addAttr(ExprAttrs * attrs, AttrPath && attrPath, const ParserLocation & loc, Expr * e, const ParserLocation & exprLoc);
void addAttr(ExprAttrs * attrs, AttrPath & attrPath, const Symbol & symbol, ExprAttrs::AttrDef && def);
Formals * validateFormals(Formals * formals, PosIdx pos = noPos, Symbol arg = {});
Expr * stripIndentation(const PosIdx pos,
std::vector<std::pair<PosIdx, std::variant<Expr *, StringToken>>> && es);
Expand Down Expand Up @@ -120,64 +121,29 @@ inline void ParserState::addAttr(ExprAttrs * attrs, AttrPath && attrPath, const
// Checking attrPath validity.
// ===========================
for (i = attrPath.begin(); i + 1 < attrPath.end(); i++) {
ExprAttrs * nested;
if (i->symbol) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
if (j != attrs->attrs.end()) {
if (j->second.kind != ExprAttrs::AttrDef::Kind::Inherited) {
ExprAttrs * attrs2 = dynamic_cast<ExprAttrs *>(j->second.e);
if (!attrs2) dupAttr(attrPath, pos, j->second.pos);
attrs = attrs2;
} else
nested = dynamic_cast<ExprAttrs *>(j->second.e);
if (!nested) {
attrPath.erase(i + 1, attrPath.end());
dupAttr(attrPath, pos, j->second.pos);
}
} else {
ExprAttrs * nested = new ExprAttrs;
nested = new ExprAttrs;
attrs->attrs[i->symbol] = ExprAttrs::AttrDef(nested, pos);
attrs = nested;
}
} else {
ExprAttrs *nested = new ExprAttrs;
nested = new ExprAttrs;
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, nested, pos));
attrs = nested;
}
attrs = nested;
}
// Expr insertion.
// ==========================
if (i->symbol) {
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(i->symbol);
if (j != attrs->attrs.end()) {
// This attr path is already defined. However, if both
// e and the expr pointed by the attr path are two attribute sets,
// we want to merge them.
// Otherwise, throw an error.
auto ae = dynamic_cast<ExprAttrs *>(e);
auto jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);
if (jAttrs && ae) {
if (ae->inheritFromExprs && !jAttrs->inheritFromExprs)
jAttrs->inheritFromExprs = std::make_unique<std::vector<Expr *>>();
for (auto & ad : ae->attrs) {
auto j2 = jAttrs->attrs.find(ad.first);
if (j2 != jAttrs->attrs.end()) // Attr already defined in iAttrs, error.
dupAttr(ad.first, j2->second.pos, ad.second.pos);
jAttrs->attrs.emplace(ad.first, ad.second);
if (ad.second.kind == ExprAttrs::AttrDef::Kind::InheritedFrom) {
auto & sel = dynamic_cast<ExprSelect &>(*ad.second.e);
auto & from = dynamic_cast<ExprInheritFrom &>(*sel.e);
from.displ += jAttrs->inheritFromExprs->size();
}
}
jAttrs->dynamicAttrs.insert(jAttrs->dynamicAttrs.end(), ae->dynamicAttrs.begin(), ae->dynamicAttrs.end());
if (ae->inheritFromExprs) {
jAttrs->inheritFromExprs->insert(jAttrs->inheritFromExprs->end(),
ae->inheritFromExprs->begin(), ae->inheritFromExprs->end());
}
} else {
dupAttr(attrPath, pos, j->second.pos);
}
} else {
// This attr path is not defined. Let's create it.
attrs->attrs.emplace(i->symbol, ExprAttrs::AttrDef(e, pos));
e->setName(i->symbol);
}
addAttr(attrs, attrPath, i->symbol, ExprAttrs::AttrDef(e, pos));
} else {
attrs->dynamicAttrs.push_back(ExprAttrs::DynamicAttrDef(i->expr, e, pos));
}
Expand All @@ -189,6 +155,60 @@ inline void ParserState::addAttr(ExprAttrs * attrs, AttrPath && attrPath, const
}
}

/**
* Precondition: attrPath is used for error messages and should already contain
* symbol as its last element.
*/
inline void ParserState::addAttr(ExprAttrs * attrs, AttrPath & attrPath, const Symbol & symbol, ExprAttrs::AttrDef && def)
{
ExprAttrs::AttrDefs::iterator j = attrs->attrs.find(symbol);
if (j != attrs->attrs.end()) {
// This attr path is already defined. However, if both
// e and the expr pointed by the attr path are two attribute sets,
// we want to merge them.
// Otherwise, throw an error.
auto ae = dynamic_cast<ExprAttrs *>(def.e);
auto jAttrs = dynamic_cast<ExprAttrs *>(j->second.e);

// N.B. In a world in which we are less bound by our past mistakes, we
// would also test that jAttrs and ae are not recursive. The effect of
// not doing so is that any `rec` marker on ae is discarded, and any
// `rec` marker on jAttrs will apply to the attributes in ae.
// See https://github.com/NixOS/nix/issues/9020.
if (jAttrs && ae) {
if (ae->inheritFromExprs && !jAttrs->inheritFromExprs)
jAttrs->inheritFromExprs = std::make_unique<std::vector<Expr *>>();
for (auto & ad : ae->attrs) {
if (ad.second.kind == ExprAttrs::AttrDef::Kind::InheritedFrom) {
auto & sel = dynamic_cast<ExprSelect &>(*ad.second.e);
auto & from = dynamic_cast<ExprInheritFrom &>(*sel.e);
from.displ += jAttrs->inheritFromExprs->size();
}
attrPath.emplace_back(AttrName(ad.first));
addAttr(jAttrs, attrPath, ad.first, std::move(ad.second));
attrPath.pop_back();
}
ae->attrs.clear();
jAttrs->dynamicAttrs.insert(jAttrs->dynamicAttrs.end(),
std::make_move_iterator(ae->dynamicAttrs.begin()),
std::make_move_iterator(ae->dynamicAttrs.end()));
ae->dynamicAttrs.clear();
if (ae->inheritFromExprs) {
jAttrs->inheritFromExprs->insert(jAttrs->inheritFromExprs->end(),
std::make_move_iterator(ae->inheritFromExprs->begin()),
std::make_move_iterator(ae->inheritFromExprs->end()));
ae->inheritFromExprs = nullptr;
}
} else {
dupAttr(attrPath, def.pos, j->second.pos);
}
} else {
// This attr path is not defined. Let's create it.
attrs->attrs.emplace(symbol, def);
def.e->setName(symbol);
}
}

inline Formals * ParserState::validateFormals(Formals * formals, PosIdx pos, Symbol arg)
{
std::sort(formals->formals.begin(), formals->formals.end(),
Expand Down
8 changes: 4 additions & 4 deletions tests/functional/lang/parse-fail-mixed-nested-attrs1.err.exp
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
error: attribute 'z' already defined at «stdin»:3:16
at «stdin»:2:3:
1| {
error: attribute 'x.z' already defined at «stdin»:2:3
at «stdin»:3:16:
2| x.z = 3;
| ^
3| x = { y = 3; z = 3; };
| ^
4| }
8 changes: 4 additions & 4 deletions tests/functional/lang/parse-fail-mixed-nested-attrs2.err.exp
View file
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
error: attribute 'y' already defined at «stdin»:3:9
at «stdin»:2:3:
1| {
error: attribute 'x.y.y' already defined at «stdin»:2:3
at «stdin»:3:9:
2| x.y.y = 3;
| ^
3| x = { y.y= 3; z = 3; };
| ^
4| }
42 changes: 42 additions & 0 deletions tests/unit/libexpr/trivial.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -177,6 +177,48 @@ namespace nix {
)
);

#define X_EXPAND_IF0(k, v) k "." v
#define X_EXPAND_IF1(k, v) k " = { " v " };"
#define X4(w, x, y, z) \
TEST_F(TrivialExpressionTest, nestedAttrsetMerge##w##x##y##z) { \
auto v = eval("{ a.b = { c = 1; d = 2; }; } == { " \
X_EXPAND_IF##w("a", X_EXPAND_IF##x("b","c = 1;")) " " \
X_EXPAND_IF##y("a", X_EXPAND_IF##z("b","d = 2;")) " }"); \
ASSERT_THAT(v, IsTrue()); \
}; \
TEST_F(TrivialExpressionTest, nestedAttrsetMergeDup##w##x##y##z) { \
ASSERT_THROW(eval("{ " \
X_EXPAND_IF##w("a", X_EXPAND_IF##x("b","c = 1;")) " " \
X_EXPAND_IF##y("a", X_EXPAND_IF##z("b","c = 2;")) " }"), Error); \
}; \
TEST_F(TrivialExpressionTest, nestedAttrsetMergeLet##w##x##y##z) { \
auto v = eval("{ b = { c = 1; d = 2; }; } == (let " \
X_EXPAND_IF##w("a", X_EXPAND_IF##x("b","c = 1;")) " " \
X_EXPAND_IF##y("a", X_EXPAND_IF##z("b","d = 2;")) " in a)"); \
ASSERT_THAT(v, IsTrue()); \
};
#define X3(...) X4(__VA_ARGS__, 0) X4(__VA_ARGS__, 1)
#define X2(...) X3(__VA_ARGS__, 0) X3(__VA_ARGS__, 1)
#define X1(...) X2(__VA_ARGS__, 0) X2(__VA_ARGS__, 1)
X1(0) X1(1)
#undef X_EXPAND_IF0
#undef X_EXPAND_IF1
#undef X1
#undef X2
#undef X3
#undef X4

// This is for backwards compatibility, not because we like it.
// See https://github.com/NixOS/nix/issues/9020.
TEST_F(TrivialExpressionTest, regrettableRecAttrsetMerge) {
auto v = eval("{ a = rec { b = c + 1; d = 2; }; a.c = d + 3; }.a.b");
ASSERT_THAT(v, IsIntEq(6));
}

TEST_F(TrivialExpressionTest, attrsetMergeDropsLaterRec) {
ASSERT_THROW(eval("{ a.b = 1; a = rec { c = d + 2; d = 3; }; }.c"), Error);
}

TEST_F(TrivialExpressionTest, functor) {
auto v = eval("{ __functor = self: arg: self.v + arg; v = 10; } 5");
ASSERT_THAT(v, IsIntEq(15));
Expand Down

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