[Clang] Added check for unexpanded pack in attribute [[assume]]

[azmat-y]

Added check for unexpanded parameter pack in attribute [[assume]]. This solves #91232.

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[llvmbot]

@llvm/pr-subscribers-clang

Author: Azmat Yusuf (azmat-y)

Changes

Added check for unexpanded parameter pack in attribute [[assume]]. This solves #91232.

---

Full diff: https://github.com/llvm/llvm-project/pull/91841.diff

1 Files Affected:

• (modified) clang/lib/Sema/SemaStmtAttr.cpp (+5)

diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index 1c84830b6ddd2..36f8ecadcfab7 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -670,6 +670,11 @@ ExprResult Sema::ActOnCXXAssumeAttr(Stmt *St, const ParsedAttr &A,
   }
 
   auto *Assumption = A.getArgAsExpr(0);
+
+  if (DiagnoseUnexpandedParameterPack(Assumption)) {
+    return ExprError();
+  }
+
   if (Assumption->getDependence() == ExprDependence::None) {
     ExprResult Res = BuildCXXAssumeExpr(Assumption, A.getAttrName(), Range);
     if (Res.isInvalid())

[Sirraide]

This needs tests to make sure this is actually doing what it’s supposed to do.

[azmat-y]

Would I be correct in assuming that the test would be somewhat similar to this.

llvm-project/clang/test/Sema/unroll-template-value-crash.cpp

// RUN: %clang_cc1 -x c++ -verify %s
// expected-no-diagnostics

template <int Unroll> void foo() {
  #pragma unroll Unroll
  for (int i = 0; i < Unroll; ++i);

  #pragma GCC unroll Unroll
  for (int i = 0; i < Unroll; ++i);
}

Can you point me towards information on clang_cc1 and similar arguments used for lit. I have scanned through lit but could not find a mention for it.

[Sirraide]

I’d recommend just adding the tests to wherever the [[assume]] attribute is already being tested; that’d be somewhere in test/SemaCXX