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Ruby: add more docs for splat flow

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Harry Maclean
2023-09-14 09:22:36 +01:00
parent 97ed5b8afb
commit 29a8a82e92
1 changed files with 31 additions and 4 deletions
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35
ruby/ql/lib/codeql/ruby/dataflow/internal/DataFlowPrivate.qll
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@@ -1280,6 +1280,16 @@ module ArgumentNodes {
override string toStringImpl() { result = "*" }
}
/**
* A data-flow node that holds data from values inside splat arguments.
* For example, in the following call
*
* ```rb
* foo(1, 2, *[3, 4])
* ```
*
* We add read steps such that `3` flows into `SynthSplatArgumentElementNode(2)` and `4` flows into `SynthSplatArgumentElementNode(3)`.
*/
class SynthSplatArgumentElementNode extends NodeImpl, TSynthSplatArgumentElementNode {
CfgNodes::ExprNodes::CallCfgNode c;
int n;
@@ -1535,8 +1545,18 @@ predicate storeStepCommon(Node node1, ContentSet c, Node node2) {
)
}
// Store from TSynthSplatArgumentElementNode(n)
// into TSynthSplatArgumentNode[n]
/**
* A store step from a `SynthSplatArgumentElementNode` into a `SynthSplatArgumentNode`.
* For example in
*
* ```rb
* foo(1, 2, *[3, 4])
* ```
*
* We have flow from `3` into `SynthSplatArgumentElementNode(2)`. This step stores the value from this node into element `2` of the `SynthSplatArgumentNode`.
*
* This allows us to match values inside splat arguments to the correct parameter in the callable.
*/
predicate synthSplatArgumentElementStoreStep(
SynthSplatArgumentElementNode node1, ContentSet c, SynthSplatArgumentNode node2
) {
@@ -1606,7 +1626,15 @@ predicate readStepCommon(Node node1, ContentSet c, Node node2) {
node2 = node1.(SynthSplatParameterNode).getAParameter(c)
}
// read from splat arg to synth splat arg element
/**
* A read step from a splat argument to a `SynthSplatArgumentElementNode`.
* For example in
* ```rb
* foo(x, y, *[1, 2])
* ```
*
* we read `1` into `SynthSplatArgumentElementNode(2)` and `2` into `SynthSplatArgumentElementNode(3)`.
*/
predicate synthSplatArgumentElementReadStep(
Node node1, ContentSet c, SynthSplatArgumentElementNode node2
) {
@@ -1665,7 +1693,6 @@ predicate readStep(Node node1, ContentSet c, Node node2) {
c = getPositionalContent(e.getReadPosition())
)
or
// TODO: convert into the above form
synthSplatArgumentElementReadStep(node1, c, node2)
or
readStepCommon(node1, c, node2)