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Merge pull request #19971 from hvitved/rust/type-inference-for-range
Rust: Improve type inference for `for` loops and range expressions
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‎rust/ql/lib/change-notes/2025-07-07-type-inference-for-loops.md‎

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@@ -0,0 +1,4 @@
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---
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category: minorAnalysis
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---
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* Type inference has been improved for `for` loops and range expressions, which improves call resolution and may ultimately lead to more query results.

‎rust/ql/lib/codeql/rust/elements/RangeExprExt.qll‎

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@@ -0,0 +1,75 @@
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/**
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* This module provides sub classes of the `RangeExpr` class.
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*/
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private import rust
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/**
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* A range-from expression. For example:
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* ```rust
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* let x = 10..;
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* ```
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*/
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final class RangeFromExpr extends RangeExpr {
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RangeFromExpr() {
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this.getOperatorName() = ".." and
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this.hasStart() and
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not this.hasEnd()
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}
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}
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/**
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* A range-to expression. For example:
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* ```rust
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* let x = ..10;
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* ```
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*/
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final class RangeToExpr extends RangeExpr {
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RangeToExpr() {
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this.getOperatorName() = ".." and
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not this.hasStart() and
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this.hasEnd()
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}
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}
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/**
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* A range-from-to expression. For example:
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* ```rust
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* let x = 10..20;
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* ```
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*/
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final class RangeFromToExpr extends RangeExpr {
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RangeFromToExpr() {
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this.getOperatorName() = ".." and
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this.hasStart() and
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this.hasEnd()
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}
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}
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/**
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* A range-inclusive expression. For example:
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* ```rust
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* let x = 1..=10;
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* ```
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*/
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final class RangeInclusiveExpr extends RangeExpr {
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RangeInclusiveExpr() {
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this.getOperatorName() = "..=" and
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this.hasStart() and
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this.hasEnd()
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}
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}
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/**
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* A range-to-inclusive expression. For example:
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* ```rust
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* let x = ..=10;
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* ```
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*/
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final class RangeToInclusiveExpr extends RangeExpr {
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RangeToInclusiveExpr() {
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this.getOperatorName() = "..=" and
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not this.hasStart() and
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this.hasEnd()
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}
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}

‎rust/ql/lib/codeql/rust/frameworks/stdlib/Stdlib.qll‎

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@@ -50,6 +50,72 @@ class ResultEnum extends Enum {
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Variant getErr() { result = this.getVariant("Err") }
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}
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/**
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* The [`Range` struct][1].
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*
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* [1]: https://doc.rust-lang.org/core/ops/struct.Range.html
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*/
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class RangeStruct extends Struct {
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RangeStruct() { this.getCanonicalPath() = "core::ops::range::Range" }
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/** Gets the `start` field. */
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StructField getStart() { result = this.getStructField("start") }
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/** Gets the `end` field. */
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StructField getEnd() { result = this.getStructField("end") }
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}
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/**
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* The [`RangeFrom` struct][1].
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*
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* [1]: https://doc.rust-lang.org/core/ops/struct.RangeFrom.html
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*/
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class RangeFromStruct extends Struct {
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RangeFromStruct() { this.getCanonicalPath() = "core::ops::range::RangeFrom" }
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/** Gets the `start` field. */
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StructField getStart() { result = this.getStructField("start") }
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}
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/**
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* The [`RangeTo` struct][1].
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*
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* [1]: https://doc.rust-lang.org/core/ops/struct.RangeTo.html
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*/
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class RangeToStruct extends Struct {
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RangeToStruct() { this.getCanonicalPath() = "core::ops::range::RangeTo" }
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/** Gets the `end` field. */
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StructField getEnd() { result = this.getStructField("end") }
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}
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/**
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* The [`RangeInclusive` struct][1].
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*
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* [1]: https://doc.rust-lang.org/core/ops/struct.RangeInclusive.html
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*/
97+
class RangeInclusiveStruct extends Struct {
98+
RangeInclusiveStruct() { this.getCanonicalPath() = "core::ops::range::RangeInclusive" }
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/** Gets the `start` field. */
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StructField getStart() { result = this.getStructField("start") }
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/** Gets the `end` field. */
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StructField getEnd() { result = this.getStructField("end") }
105+
}
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/**
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* The [`RangeToInclusive` struct][1].
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*
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* [1]: https://doc.rust-lang.org/core/ops/struct.RangeToInclusive.html
111+
*/
112+
class RangeToInclusiveStruct extends Struct {
113+
RangeToInclusiveStruct() { this.getCanonicalPath() = "core::ops::range::RangeToInclusive" }
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/** Gets the `end` field. */
116+
StructField getEnd() { result = this.getStructField("end") }
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}
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/**
54120
* The [`Future` trait][1].
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*
@@ -66,6 +132,38 @@ class FutureTrait extends Trait {
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}
67133
}
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135+
/**
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* The [`Iterator` trait][1].
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*
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* [1]: https://doc.rust-lang.org/std/iter/trait.Iterator.html
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*/
140+
class IteratorTrait extends Trait {
141+
IteratorTrait() { this.getCanonicalPath() = "core::iter::traits::iterator::Iterator" }
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143+
/** Gets the `Item` associated type. */
144+
pragma[nomagic]
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TypeAlias getItemType() {
146+
result = this.getAssocItemList().getAnAssocItem() and
147+
result.getName().getText() = "Item"
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}
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}
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/**
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* The [`IntoIterator` trait][1].
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*
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* [1]: https://doc.rust-lang.org/std/iter/trait.IntoIterator.html
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*/
156+
class IntoIteratorTrait extends Trait {
157+
IntoIteratorTrait() { this.getCanonicalPath() = "core::iter::traits::collect::IntoIterator" }
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159+
/** Gets the `Item` associated type. */
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pragma[nomagic]
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TypeAlias getItemType() {
162+
result = this.getAssocItemList().getAnAssocItem() and
163+
result.getName().getText() = "Item"
164+
}
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}
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/**
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* The [`String` struct][1].
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*

‎rust/ql/lib/codeql/rust/internal/Type.qll‎

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@@ -421,21 +421,25 @@ final class ImplTypeAbstraction extends TypeAbstraction, Impl {
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}
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423423
final class TraitTypeAbstraction extends TypeAbstraction, Trait {
424-
override TypeParamTypeParameter getATypeParameter() {
425-
result.getTypeParam() = this.getGenericParamList().getATypeParam()
424+
override TypeParameter getATypeParameter() {
425+
result.(TypeParamTypeParameter).getTypeParam() = this.getGenericParamList().getATypeParam()
426+
or
427+
result.(AssociatedTypeTypeParameter).getTrait() = this
426428
}
427429
}
428430

429431
final class TypeBoundTypeAbstraction extends TypeAbstraction, TypeBound {
430-
override TypeParamTypeParameter getATypeParameter() { none() }
432+
override TypeParameter getATypeParameter() { none() }
431433
}
432434

433435
final class SelfTypeBoundTypeAbstraction extends TypeAbstraction, Name {
434-
SelfTypeBoundTypeAbstraction() { any(Trait trait).getName() = this }
436+
private TraitTypeAbstraction trait;
437+
438+
SelfTypeBoundTypeAbstraction() { trait.getName() = this }
435439

436-
override TypeParamTypeParameter getATypeParameter() { none() }
440+
override TypeParameter getATypeParameter() { none() }
437441
}
438442

439443
final class ImplTraitTypeReprAbstraction extends TypeAbstraction, ImplTraitTypeRepr {
440-
override TypeParamTypeParameter getATypeParameter() { none() }
444+
override TypeParameter getATypeParameter() { none() }
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}

‎rust/ql/lib/codeql/rust/internal/TypeInference.qll‎

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@@ -231,6 +231,24 @@ private Type inferAssignmentOperationType(AstNode n, TypePath path) {
231231
result = TUnit()
232232
}
233233

234+
pragma[nomagic]
235+
private Struct getRangeType(RangeExpr re) {
236+
re instanceof RangeFromExpr and
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result instanceof RangeFromStruct
238+
or
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re instanceof RangeToExpr and
240+
result instanceof RangeToStruct
241+
or
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re instanceof RangeFromToExpr and
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result instanceof RangeStruct
244+
or
245+
re instanceof RangeInclusiveExpr and
246+
result instanceof RangeInclusiveStruct
247+
or
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re instanceof RangeToInclusiveExpr and
249+
result instanceof RangeToInclusiveStruct
250+
}
251+
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/**
235253
* Holds if the type tree of `n1` at `prefix1` should be equal to the type tree
236254
* of `n2` at `prefix2` and type information should propagate in both directions
@@ -296,6 +314,13 @@ private predicate typeEquality(AstNode n1, TypePath prefix1, AstNode n2, TypePat
296314
n1.(ArrayRepeatExpr).getRepeatOperand() = n2 and
297315
prefix1 = TypePath::singleton(TArrayTypeParameter()) and
298316
prefix2.isEmpty()
317+
or
318+
exists(Struct s |
319+
n2 = [n1.(RangeExpr).getStart(), n1.(RangeExpr).getEnd()] and
320+
prefix1 = TypePath::singleton(TTypeParamTypeParameter(s.getGenericParamList().getATypeParam())) and
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prefix2.isEmpty() and
322+
s = getRangeType(n1)
323+
)
299324
}
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301326
pragma[nomagic]
@@ -1062,7 +1087,7 @@ private TraitType inferAsyncBlockExprRootType(AsyncBlockExpr abe) {
10621087
result = getFutureTraitType()
10631088
}
10641089

1065-
final class AwaitTarget extends Expr {
1090+
final private class AwaitTarget extends Expr {
10661091
AwaitTarget() { this = any(AwaitExpr ae).getExpr() }
10671092

10681093
Type getTypeAt(TypePath path) { result = inferType(this, path) }
@@ -1098,6 +1123,12 @@ private class Vec extends Struct {
10981123
pragma[nomagic]
10991124
private Type inferArrayExprType(ArrayExpr ae) { exists(ae) and result = TArrayType() }
11001125

1126+
/**
1127+
* Gets the root type of the range expression `re`.
1128+
*/
1129+
pragma[nomagic]
1130+
private Type inferRangeExprType(RangeExpr re) { result = TStruct(getRangeType(re)) }
1131+
11011132
/**
11021133
* According to [the Rust reference][1]: _"array and slice-typed expressions
11031134
* can be indexed with a `usize` index ... For other types an index expression
@@ -1134,23 +1165,49 @@ private Type inferIndexExprType(IndexExpr ie, TypePath path) {
11341165
)
11351166
}
11361167

1168+
final private class ForIterableExpr extends Expr {
1169+
ForIterableExpr() { this = any(ForExpr fe).getIterable() }
1170+
1171+
Type getTypeAt(TypePath path) { result = inferType(this, path) }
1172+
}
1173+
1174+
private module ForIterableSatisfiesConstraintInput implements
1175+
SatisfiesConstraintInputSig<ForIterableExpr>
1176+
{
1177+
predicate relevantConstraint(ForIterableExpr term, Type constraint) {
1178+
exists(term) and
1179+
exists(Trait t | t = constraint.(TraitType).getTrait() |
1180+
// TODO: Remove the line below once we can handle the `impl<I: Iterator> IntoIterator for I` implementation
1181+
t instanceof IteratorTrait or
1182+
t instanceof IntoIteratorTrait
1183+
)
1184+
}
1185+
}
1186+
1187+
pragma[nomagic]
1188+
private AssociatedTypeTypeParameter getIteratorItemTypeParameter() {
1189+
result.getTypeAlias() = any(IteratorTrait t).getItemType()
1190+
}
1191+
1192+
pragma[nomagic]
1193+
private AssociatedTypeTypeParameter getIntoIteratorItemTypeParameter() {
1194+
result.getTypeAlias() = any(IntoIteratorTrait t).getItemType()
1195+
}
1196+
11371197
pragma[nomagic]
11381198
private Type inferForLoopExprType(AstNode n, TypePath path) {
11391199
// type of iterable -> type of pattern (loop variable)
1140-
exists(ForExpr fe, Type iterableType, TypePath iterablePath |
1200+
exists(ForExpr fe, TypePath exprPath, AssociatedTypeTypeParameter tp |
11411201
n = fe.getPat() and
1142-
iterableType = inferType(fe.getIterable(), iterablePath) and
1143-
result = iterableType and
1144-
(
1145-
iterablePath.isCons(any(Vec v).getElementTypeParameter(), path)
1146-
or
1147-
iterablePath.isCons(any(ArrayTypeParameter tp), path)
1148-
or
1149-
iterablePath
1150-
.stripPrefix(TypePath::cons(TRefTypeParameter(),
1151-
TypePath::singleton(any(SliceTypeParameter tp)))) = path
1152-
// TODO: iterables (general case for containers, ranges etc)
1153-
)
1202+
SatisfiesConstraint<ForIterableExpr, ForIterableSatisfiesConstraintInput>::satisfiesConstraintType(fe.getIterable(),
1203+
_, exprPath, result) and
1204+
exprPath.isCons(tp, path)
1205+
|
1206+
tp = getIntoIteratorItemTypeParameter()
1207+
or
1208+
// TODO: Remove once we can handle the `impl<I: Iterator> IntoIterator for I` implementation
1209+
tp = getIteratorItemTypeParameter() and
1210+
inferType(fe.getIterable()) != TArrayType()
11541211
)
11551212
}
11561213

@@ -1589,6 +1646,9 @@ private module Cached {
15891646
result = inferArrayExprType(n) and
15901647
path.isEmpty()
15911648
or
1649+
result = inferRangeExprType(n) and
1650+
path.isEmpty()
1651+
or
15921652
result = inferIndexExprType(n, path)
15931653
or
15941654
result = inferForLoopExprType(n, path)

‎rust/ql/lib/rust.qll‎

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@@ -15,6 +15,7 @@ import codeql.rust.elements.AsyncBlockExpr
1515
import codeql.rust.elements.Variable
1616
import codeql.rust.elements.NamedFormatArgument
1717
import codeql.rust.elements.PositionalFormatArgument
18+
import codeql.rust.elements.RangeExprExt
1819
private import codeql.rust.elements.Call as Call
1920

2021
class Call = Call::Call;

‎rust/ql/test/library-tests/dataflow/sources/TaintSources.expected‎

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@@ -55,10 +55,16 @@
5555
| test.rs:412:31:412:38 | ...::read | Flow source 'FileSource' of type file (DEFAULT). |
5656
| test.rs:417:22:417:39 | ...::read_to_string | Flow source 'FileSource' of type file (DEFAULT). |
5757
| test.rs:417:22:417:39 | ...::read_to_string | Flow source 'FileSource' of type file (DEFAULT). |
58+
| test.rs:423:22:423:25 | path | Flow source 'FileSource' of type file (DEFAULT). |
59+
| test.rs:424:27:424:35 | file_name | Flow source 'FileSource' of type file (DEFAULT). |
5860
| test.rs:430:22:430:34 | ...::read_link | Flow source 'FileSource' of type file (DEFAULT). |
5961
| test.rs:439:31:439:45 | ...::read | Flow source 'FileSource' of type file (DEFAULT). |
6062
| test.rs:444:31:444:45 | ...::read | Flow source 'FileSource' of type file (DEFAULT). |
6163
| test.rs:449:22:449:46 | ...::read_to_string | Flow source 'FileSource' of type file (DEFAULT). |
64+
| test.rs:455:26:455:29 | path | Flow source 'FileSource' of type file (DEFAULT). |
65+
| test.rs:455:26:455:29 | path | Flow source 'FileSource' of type file (DEFAULT). |
66+
| test.rs:456:31:456:39 | file_name | Flow source 'FileSource' of type file (DEFAULT). |
67+
| test.rs:456:31:456:39 | file_name | Flow source 'FileSource' of type file (DEFAULT). |
6268
| test.rs:462:22:462:41 | ...::read_link | Flow source 'FileSource' of type file (DEFAULT). |
6369
| test.rs:472:20:472:38 | ...::open | Flow source 'FileSource' of type file (DEFAULT). |
6470
| test.rs:506:21:506:39 | ...::open | Flow source 'FileSource' of type file (DEFAULT). |

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