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Rust: Implement support for inference of type aliases #19146

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paldepind merged 3 commits into from
Apr 7, 2025
Merged

Rust: Implement support for inference of type aliases #19146

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e7027f0
Rust: Add type inference tests for type aliases
paldepind Mar 28, 2025
a1d36c0
Rust: Implement support for inference of type aliases
paldepind Mar 28, 2025
acc565f
Rust: Refactor PathMention as suggested in review
paldepind Apr 7, 2025
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49 changes: 48 additions & 1 deletion rust/ql/lib/codeql/rust/internal/TypeMention.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -53,9 +53,25 @@ class TypeReprMention extends TypeMention, TypeRepr {
or
result = this.(PathTypeRepr).getPath().(PathMention).resolveType()
}

override Type resolveTypeAt(TypePath path) {
result = this.(PathTypeRepr).getPath().(PathMention).resolveTypeAt(path)
or
not exists(this.(PathTypeRepr).getPath()) and
result = super.resolveTypeAt(path)
}
}

/** Holds if `path` resolves the type alias `alias` with the definition `rhs`. */
private predicate resolvePathAlias(Path path, TypeAlias alias, TypeReprMention rhs) {
alias = resolvePath(path) and rhs = alias.getTypeRepr()
}

class PathMention extends TypeMention, Path {
abstract class PathMention extends TypeMention, Path { }

class NonAliasPathMention extends PathMention {
NonAliasPathMention() { not resolvePathAlias(this, _, _) }

override TypeMention getTypeArgument(int i) {
result = this.getSegment().getGenericArgList().getTypeArg(i)
or
Expand Down Expand Up @@ -98,6 +114,37 @@ class PathMention extends TypeMention, Path {
}
}

class AliasPathMention extends PathMention {
TypeAlias alias;
TypeReprMention rhs;

AliasPathMention() { resolvePathAlias(this, alias, rhs) }

override TypeMention getTypeArgument(int i) {
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result = this.getSegment().getGenericArgList().getTypeArg(i)
}

/** Get the `i`th type parameter of the alias itself. */
private TypeParameter getTypeParameter(int i) {
result = TTypeParamTypeParameter(alias.getGenericParamList().getTypeParam(i))
}

override Type resolveType() { result = rhs.resolveType() }

override Type resolveTypeAt(TypePath path) {
result = rhs.resolveTypeAt(path) and
not result = this.getTypeParameter(_)
or
exists(TypeParameter tp, TypeMention arg, TypePath prefix, TypePath suffix, int i |
tp = rhs.resolveTypeAt(prefix) and
tp = this.getTypeParameter(i) and
arg = this.getTypeArgument(i) and
result = arg.resolveTypeAt(suffix) and
path = prefix.append(suffix)
)
}
}

// Used to represent implicit `Self` type arguments in traits and `impl` blocks,
// see `PathMention` for details.
class TypeParamMention extends TypeMention, TypeParam {
Expand Down
10 changes: 5 additions & 5 deletions rust/ql/test/library-tests/type-inference/main.rs
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Expand Up @@ -569,11 +569,11 @@ mod type_aliases {
// Alias to another alias
type AliasToAlias<A4> = AnotherPair<A4>;

// Alias that appears nested withing another alias
// Alias that appears nested within another alias
type NestedAlias<A5> = AnotherPair<AliasToAlias<A5>>;

fn g(t: NestedAlias<S3>) {
let x = t.unwrapSnd().unwrapSnd(); // $ method=unwrapSnd MISSING: type=x:S3
let x = t.unwrapSnd().unwrapSnd(); // $ method=unwrapSnd type=x:S3
println!("{:?}", x);
}

Expand All @@ -583,15 +583,15 @@ mod type_aliases {
println!("{:?}", p1);

// Type can be only inferred from the type alias
let p2: MyPair = PairOption::PairNone(); // $ MISSING: type=p2:Fst.S1 MISSING: type=p2:Snd.S2
let p2: MyPair = PairOption::PairNone(); // $ type=p2:Fst.S1 type=p2:Snd.S2
println!("{:?}", p2);

// First type from alias, second from constructor
let p3: AnotherPair<_> = PairOption::PairSnd(S3); // $ MISSING: type=p3:Fst.S2
let p3: AnotherPair<_> = PairOption::PairSnd(S3); // $ type=p3:Fst.S2
println!("{:?}", p3);

// First type from alias definition, second from argument to alias
let p3: AnotherPair<S3> = PairOption::PairNone(); // $ SPURIOUS: type=p3:Fst.S3 MISSING: type=p3:Snd.S3
let p3: AnotherPair<S3> = PairOption::PairNone(); // $ type=p3:Fst.S2 type=p3:Snd.S3
println!("{:?}", p3);

g(PairOption::PairSnd(PairOption::PairSnd(S3)));
Expand Down
38 changes: 32 additions & 6 deletions rust/ql/test/library-tests/type-inference/type-inference.expected
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Original file line number Diff line number Diff line change
Expand Up @@ -510,9 +510,21 @@ inferType
| main.rs:549:41:549:43 | snd | | main.rs:543:15:543:17 | Snd |
| main.rs:549:49:549:51 | snd | | main.rs:543:15:543:17 | Snd |
| main.rs:575:10:575:10 | t | | main.rs:535:5:541:5 | PairOption |
| main.rs:575:10:575:10 | t | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:575:10:575:10 | t | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:575:10:575:10 | t | Snd | main.rs:535:5:541:5 | PairOption |
| main.rs:575:10:575:10 | t | Snd.Fst | main.rs:557:5:558:14 | S2 |
| main.rs:575:10:575:10 | t | Snd.Snd | main.rs:560:5:561:14 | S3 |
| main.rs:576:13:576:13 | x | | main.rs:560:5:561:14 | S3 |
| main.rs:576:17:576:17 | t | | main.rs:535:5:541:5 | PairOption |
| main.rs:576:17:576:17 | t | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:576:17:576:17 | t | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:576:17:576:17 | t | Snd | main.rs:535:5:541:5 | PairOption |
| main.rs:576:17:576:17 | t | Snd.Fst | main.rs:557:5:558:14 | S2 |
| main.rs:576:17:576:17 | t | Snd.Snd | main.rs:560:5:561:14 | S3 |
| main.rs:576:17:576:29 | t.unwrapSnd() | | main.rs:535:5:541:5 | PairOption |
| main.rs:576:17:576:29 | t.unwrapSnd() | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:576:17:576:29 | t.unwrapSnd() | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:576:17:576:41 | ... .unwrapSnd() | | main.rs:560:5:561:14 | S3 |
| main.rs:577:26:577:26 | x | | main.rs:560:5:561:14 | S3 |
| main.rs:582:13:582:14 | p1 | | main.rs:535:5:541:5 | PairOption |
| main.rs:582:13:582:14 | p1 | Fst | main.rs:554:5:555:14 | S1 |
| main.rs:582:13:582:14 | p1 | Snd | main.rs:557:5:558:14 | S2 |
Expand All @@ -525,26 +537,40 @@ inferType
| main.rs:583:26:583:27 | p1 | Fst | main.rs:554:5:555:14 | S1 |
| main.rs:583:26:583:27 | p1 | Snd | main.rs:557:5:558:14 | S2 |
| main.rs:586:13:586:14 | p2 | | main.rs:535:5:541:5 | PairOption |
| main.rs:586:13:586:14 | p2 | Fst | main.rs:554:5:555:14 | S1 |
| main.rs:586:13:586:14 | p2 | Snd | main.rs:557:5:558:14 | S2 |
| main.rs:586:26:586:47 | ...::PairNone(...) | | main.rs:535:5:541:5 | PairOption |
| main.rs:586:26:586:47 | ...::PairNone(...) | Fst | main.rs:554:5:555:14 | S1 |
| main.rs:586:26:586:47 | ...::PairNone(...) | Snd | main.rs:557:5:558:14 | S2 |
| main.rs:587:26:587:27 | p2 | | main.rs:535:5:541:5 | PairOption |
| main.rs:587:26:587:27 | p2 | Fst | main.rs:554:5:555:14 | S1 |
| main.rs:587:26:587:27 | p2 | Snd | main.rs:557:5:558:14 | S2 |
| main.rs:590:13:590:14 | p3 | | main.rs:535:5:541:5 | PairOption |
| main.rs:590:13:590:14 | p3 | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:590:13:590:14 | p3 | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:590:34:590:56 | ...::PairSnd(...) | | main.rs:535:5:541:5 | PairOption |
| main.rs:590:34:590:56 | ...::PairSnd(...) | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:590:34:590:56 | ...::PairSnd(...) | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:590:54:590:55 | S3 | | main.rs:560:5:561:14 | S3 |
| main.rs:591:26:591:27 | p3 | | main.rs:535:5:541:5 | PairOption |
| main.rs:591:26:591:27 | p3 | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:591:26:591:27 | p3 | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:594:13:594:14 | p3 | | main.rs:535:5:541:5 | PairOption |
| main.rs:594:13:594:14 | p3 | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:594:13:594:14 | p3 | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:594:13:594:14 | p3 | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:594:35:594:56 | ...::PairNone(...) | | main.rs:535:5:541:5 | PairOption |
| main.rs:594:35:594:56 | ...::PairNone(...) | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:594:35:594:56 | ...::PairNone(...) | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:594:35:594:56 | ...::PairNone(...) | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:595:26:595:27 | p3 | | main.rs:535:5:541:5 | PairOption |
| main.rs:595:26:595:27 | p3 | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:595:26:595:27 | p3 | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:595:26:595:27 | p3 | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:597:11:597:54 | ...::PairSnd(...) | | main.rs:535:5:541:5 | PairOption |
| main.rs:597:11:597:54 | ...::PairSnd(...) | Fst | main.rs:560:5:561:14 | S3 |
| main.rs:597:11:597:54 | ...::PairSnd(...) | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:597:11:597:54 | ...::PairSnd(...) | Snd | main.rs:535:5:541:5 | PairOption |
| main.rs:597:11:597:54 | ...::PairSnd(...) | Snd.Fst | main.rs:557:5:558:14 | S2 |
| main.rs:597:11:597:54 | ...::PairSnd(...) | Snd.Snd | main.rs:560:5:561:14 | S3 |
| main.rs:597:31:597:53 | ...::PairSnd(...) | | main.rs:535:5:541:5 | PairOption |
| main.rs:597:31:597:53 | ...::PairSnd(...) | Fst | main.rs:557:5:558:14 | S2 |
| main.rs:597:31:597:53 | ...::PairSnd(...) | Snd | main.rs:560:5:561:14 | S3 |
| main.rs:597:51:597:52 | S3 | | main.rs:560:5:561:14 | S3 |
| main.rs:610:16:610:24 | SelfParam | | file://:0:0:0:0 | & |
Expand Down