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[BoundsSafety] Do not check for bounds-attributed output arguments in dependent contexts #9733

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Merged
merged 1 commit into from
Dec 19, 2024
Merged

[BoundsSafety] Do not check for bounds-attributed output arguments in dependent contexts #9733

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8 changes: 6 additions & 2 deletions clang/lib/Sema/SemaExpr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@
#include "clang/AST/Decl.h"
#include "clang/AST/DeclObjC.h"
#include "clang/AST/DeclTemplate.h"
#include "clang/AST/DependenceFlags.h"
#include "clang/AST/DynamicRecursiveASTVisitor.h"
#include "clang/AST/EvaluatedExprVisitor.h"
#include "clang/AST/Expr.h"
Expand Down Expand Up @@ -8332,7 +8333,7 @@ static bool checkDynamicCountPointerAsParameter(Sema &S, FunctionDecl *FDecl,
if (!ArgInfo.isCountInParamOrCountPointer() && !ArgInfo.isCountInRet() &&
!ParmInfo.isCountInParamOrCountPointer() && !ParmInfo.isCountInRet())
continue;
assert(!ActualArgExp->isValueDependent());
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Is is it still necessary to remove this, despite checking !TheCall->getDependence() before calling checkDynamicCountPointerAsParameter? Or is this something else?

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@ziqingluo-90 ziqingluo-90 Dec 18, 2024 •
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!TheCall->getDependence() implies no argument isValueDependent(). So I think that assertion becomes unreachable.

This is where I got the sense that Call->getDependence() includes dependence info of its arguments:
https://github.com/llvm/llvm-project/blob/2916352936097a35cdcaaf38a9097465adbf8cf5/clang/lib/AST/ComputeDependence.cpp#L642C1-L654C2


// Disable these checks for attribute-only mode because we don't want
// non-type-incompatibility errors in that mode.
if (!S.getLangOpts().isBoundsSafetyAttributeOnlyMode() &&
Expand Down Expand Up @@ -8903,7 +8904,10 @@ ExprResult Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
if (getLangOpts().BoundsSafetyAttributes && FDecl) {
// FIXME: We need to support function pointers and blocks that don't have
// function decl.
if (!checkDynamicCountPointerAsParameter(*this, FDecl, TheCall))

// For C++, we don't want to check for any dependent constructs.
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Nit: Maybe instead of casting enum to bool, we could be explicit TheCall->getDependence() == ExprDependence::None? We could also move the comment before if.

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@rapidsna rapidsna Dec 19, 2024 •
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Nit: "For C++, we don't want to check for any dependent constructs."

if (TheCall->getDependence() == ExprDependence::None &&
!checkDynamicCountPointerAsParameter(*this, FDecl, TheCall))
return ExprError();
if (getLangOpts().BoundsSafety)
if (!checkDynamicRangePointerAsParameter(*this, FDecl, TheCall))
Expand Down
7 changes: 5 additions & 2 deletions clang/test/BoundsSafety/Sema/unsafe-buffer-usage-interop-crash.cpp
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Expand Up @@ -11,12 +11,15 @@ class MyClass {
namespace value_dependent_assertion_violation {
// Running attribute-only mode on the C++ code below crashes
// previously.
void g(unsigned);
void g(int * __counted_by(n) * p, size_t n);

template<typename T>
struct S {
void f(T p) {
g(sizeof(p));
g(nullptr, sizeof(p));
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Are we certain this still exercises the same path as caused the crash previously, or should we keep the old function and add another?

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The old one was testing for no type checking in a dependent context, if there is no bounds attribute. Now we are testing that the same path will not be reached under a stronger condition, i.e., no type checking in a dependent context.

So the new test is stronger and covers the old one after the change of this PR.

}
};

// expected-error@-4{{incompatible dynamic count pointer argument to parameter of type 'int * __counted_by(n)*' (aka 'int **')}}
template struct S<int>; // expected-note{{in instantiation of member function 'value_dependent_assertion_violation::S<int>::f' requested here}}
}