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C++: add predicate to distinguish between array/field designators

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idrissrio
2025-04-16 16:19:26 +02:00
parent e05c030bb7
commit 49183bb82a
2 changed files with 43 additions and 4 deletions
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41
cpp/ql/lib/semmle/code/cpp/exprs/Literal.qll
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@@ -213,7 +213,27 @@ class ClassAggregateLiteral extends AggregateLiteral {
Expr getFieldExpr(Field field, int position) {
field = classType.getAField() and
aggregate_field_init(underlyingElement(this), unresolveElement(result), unresolveElement(field),
position)
position, _)
}
/**
* Holds if the `position`-th initialization of `field` in this aggregate initializer
* uses a designator (e.g., `.x =`, `[42] =`) rather than a positional initializer.
*
* This can be used to distinguish explicitly designated initializations from
* implicit positional ones.
*
* For example, in the initializer:
* ```c
* struct S { int x, y; };
* struct S s = { .x = 1, 2 };
* ```
* - `.x = 1` is a designator init, therefore `isDesignatorInit(x, 0)` holds.
* - `2` is a positional init for `.y`, therefore `isDesignatorInit(y, 1)` does **not** hold.
*/
predicate isDesignatorInit(Field field, int position) {
field = classType.getAField() and
aggregate_field_init(underlyingElement(this), _, unresolveElement(field), position, true)
}
/**
@@ -304,7 +324,24 @@ class ArrayOrVectorAggregateLiteral extends AggregateLiteral {
* - `a.getElementExpr(0, 2)` gives `789`.
*/
Expr getElementExpr(int elementIndex, int position) {
aggregate_array_init(underlyingElement(this), unresolveElement(result), elementIndex, position)
aggregate_array_init(underlyingElement(this), unresolveElement(result), elementIndex, position,
_)
}
/**
* Holds if the `position`-th initialization of the array element at `elementIndex`
* in this aggregate initializer uses a designator (e.g., `[0] = ...`) rather than
* an implicit positional initializer.
*
* For example, in:
* ```c
* int x[] = { [0] = 1, 2 };
* ```
* - `[0] = 1` is a designator init, therefore `isDesignatorInit(0, 0)` holds.
* - `2` is a positional init for `x[1]`, therefore `isDesignatorInit(1, 1)` does **not** hold.
*/
predicate isDesignatorInit(int elementIndex, int position) {
aggregate_array_init(underlyingElement(this), _, elementIndex, position, true)
}
/**