[PATCH] Permit OpenCL event_t's to be constructed from integer value 0.

[Neil Henning]

Hi rsmith,

The OpenCL specification and conformance tests have code similar to;

  void func(event_t e);
  ...
  func((event_t)0);

Clang (in OpenCL language mode) currently supports the above, but without the explicit cast, like;

  func(0);

But doesn't allow the explicit cast. This patch fixes this, and also adds in a more descriptive error for when a user does;

  (event_t)5;

and also adds in some more expected results to the OpenCL event_t tests.

Any comments or suggestions would be greatly appreciated!

http://llvm-reviews.chandlerc.com/D2860

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/Sema/SemaCast.cpp
  test/SemaOpenCL/event_t.cl

Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -6785,6 +6785,8 @@
   "return value cannot be qualified with address space">;
 def err_opencl_constant_no_init : Error<
   "variable in constant address space must be initialized">;
+def error_opencl_cast_non_zero_to_event_t : Error<
+  "cannot cast non-zero value '%0' to 'event_t'">;
 } // end of sema category
 
 let CategoryName = "OpenMP Issue" in {
Index: lib/Sema/SemaCast.cpp
===================================================================
--- lib/Sema/SemaCast.cpp
+++ lib/Sema/SemaCast.cpp
@@ -2238,6 +2238,21 @@
       return;
     }
 
+    // for OpenCL, allow casts from '0' to event_t type
+    if ((Self.getLangOpts().OpenCL) && DestType->isEventT()) {
+      llvm::APSInt intValue;
+      if(SrcExpr.get()->EvaluateAsInt(intValue, Self.getASTContext())) {
+        if(0 == intValue) {
+          return;
+        } else {
+          Self.Diag(OpRange.getBegin(), diag::error_opencl_cast_non_zero_to_event_t)
+            << intValue.toString(10) << SrcExpr.get()->getSourceRange();
+          SrcExpr = ExprError();
+          return;
+        }
+      }
+    }
+
     // Reject any other conversions to non-scalar types.
     Self.Diag(OpRange.getBegin(), diag::err_typecheck_cond_expect_scalar)
       << DestType << SrcExpr.get()->getSourceRange();
Index: test/SemaOpenCL/event_t.cl
===================================================================
--- test/SemaOpenCL/event_t.cl
+++ test/SemaOpenCL/event_t.cl
@@ -6,13 +6,18 @@
   event_t evt;  // expected-error {{the event_t type cannot be used to declare a structure or union field}}
 } evt_str = {0};
 
-void foo(event_t evt); // expected-note {{passing argument to parameter 'evt' here}}
+void foo(event_t evt); // expected-note 2 {{passing argument to parameter 'evt' here}}
 
 void kernel ker(event_t argevt) { // expected-error {{'event_t' cannot be used as the type of a kernel parameter}}
   event_t e;
+  int i;
   constant event_t const_evt; // expected-error {{the event_t type can only be used with __private address space qualifier}}
   foo(e);
   foo(0);
+  foo((event_t)0);
+  foo(i); // expected-error {{passing 'int' to parameter of incompatible type 'event_t'}}
+  foo((event_t)i); // expected-error {{used type 'event_t' where arithmetic or pointer type is required}}
   foo(5); // expected-error {{passing 'int' to parameter of incompatible type 'event_t'}}
+  foo((event_t)5); // expected-error {{cannot cast non-zero value '5' to 'event_t'}}
 }
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