[clang] c47f971 - [Sema][SVE] Don't allow sizeless objects to be thrown

[Richard Sandiford via cfe-commits]

Author: Richard Sandiford
Date: 2020-03-17T11:52:37Z
New Revision: c47f971694be0159ffddfee8a75ae515eba91439

URL: https://github.com/llvm/llvm-project/commit/c47f971694be0159ffddfee8a75ae515eba91439
DIFF: https://github.com/llvm/llvm-project/commit/c47f971694be0159ffddfee8a75ae515eba91439.diff

LOG: [Sema][SVE] Don't allow sizeless objects to be thrown

Summary:
The same rules for throwing and catching incomplete types also apply
to sizeless types.  This patch enforces that for throw statements.
It also make sure that we use "sizeless type" rather "incomplete type"
in the associated message.  (Both are correct, but "sizeless type" is
more specific and hopefully more user-friendly.)

The SVE ACLE simply extends the rule for incomplete types to
sizeless types.  However, throwing pointers to sizeless types
should not pose any real difficulty, so as an extension,
the clang implementation allows that.

Reviewers: sdesmalen, efriedma, rovka, rjmccall

Subscribers: tschuett, rkruppe, psnobl, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D76088

Added: 
    

Modified: 
    clang/include/clang/Basic/DiagnosticSemaKinds.td
    clang/lib/Sema/SemaExprCXX.cpp
    clang/test/SemaCXX/sizeless-1.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index b33e11e79604..1b82abadd8a9 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -7120,6 +7120,8 @@ def err_throw_incomplete : Error<
   "cannot throw object of incomplete type %0">;
 def err_throw_incomplete_ptr : Error<
   "cannot throw pointer to object of incomplete type %0">;
+def err_throw_sizeless : Error<
+  "cannot throw object of sizeless type %0">;
 def warn_throw_underaligned_obj : Warning<
   "underaligned exception object thrown">,
   InGroup<UnderalignedExceptionObject>;

diff  --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index f81aabb55e4c..5969b5abd399 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -956,6 +956,11 @@ bool Sema::CheckCXXThrowOperand(SourceLocation ThrowLoc,
                             E->getSourceRange()))
       return true;
 
+    if (!isPointer && Ty->isSizelessType()) {
+      Diag(ThrowLoc, diag::err_throw_sizeless) << Ty << E->getSourceRange();
+      return true;
+    }
+
     if (RequireNonAbstractType(ThrowLoc, ExceptionObjectTy,
                                diag::err_throw_abstract_type, E))
       return true;

diff  --git a/clang/test/SemaCXX/sizeless-1.cpp b/clang/test/SemaCXX/sizeless-1.cpp
index 876f5931a7db..af207550eb37 100644
--- a/clang/test/SemaCXX/sizeless-1.cpp
+++ b/clang/test/SemaCXX/sizeless-1.cpp
@@ -395,6 +395,9 @@ void cxx_only(int sel) {
   local_int16 = static_cast<svint16_t>(local_int8); // expected-error {{static_cast from 'svint8_t' (aka '__SVInt8_t') to 'svint16_t' (aka '__SVInt16_t') is not allowed}}
   sel = static_cast<int>(local_int8);               // expected-error {{static_cast from 'svint8_t' (aka '__SVInt8_t') to 'int' is not allowed}}
 
+  throw local_int8; // expected-error {{cannot throw object of sizeless type 'svint8_t'}}
+  throw global_int8_ptr;
+
   local_int8.~__SVInt8_t(); // expected-error {{object expression of non-scalar type 'svint8_t' (aka '__SVInt8_t') cannot be used in a pseudo-destructor expression}}
 
   (void)svint8_t();