From cf04d04ccf6879aa943e09ca8066105e692ab2df Mon Sep 17 00:00:00 2001
From: Anastasia Stulova <anastasia.stulova@arm.com>
Date: Tue, 5 Jan 2016 14:39:27 +0000
Subject: [PATCH] [OpenCL] Disallow taking an address of a function.

An undecorated function designator implies taking the address of a function,
which is illegal in OpenCL. Implementing a check for this earlier to allow
the error to be reported even in the presence of other more obvious errors.

Patch by Neil Hickey!

http://reviews.llvm.org/D15691

llvm-svn: 256838
---
 .../include/clang/Basic/DiagnosticParseKinds.td |  4 ++++
 clang/lib/Parse/ParseExpr.cpp                   | 17 ++++++++++++++++-
 clang/test/SemaOpenCL/cond.cl                   |  2 +-
 clang/test/SemaOpenCL/func_ptr.cl               |  3 +++
 4 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/clang/include/clang/Basic/DiagnosticParseKinds.td b/clang/include/clang/Basic/DiagnosticParseKinds.td
index 446852a86b0d..f8dee2f98cca 100644
--- a/clang/include/clang/Basic/DiagnosticParseKinds.td
+++ b/clang/include/clang/Basic/DiagnosticParseKinds.td
@@ -910,6 +910,10 @@ def warn_pragma_expected_enable_disable : Warning<
 def warn_pragma_unknown_extension : Warning<
   "unknown OpenCL extension %0 - ignoring">, InGroup<IgnoredPragmas>;
 
+// OpenCL error
+def err_opencl_taking_function_address_parser : Error<
+  "taking address of function is not allowed">;
+
 // OpenMP support.
 def warn_pragma_omp_ignored : Warning<
   "unexpected '#pragma omp ...' in program">, InGroup<SourceUsesOpenMP>, DefaultIgnore;
diff --git a/clang/lib/Parse/ParseExpr.cpp b/clang/lib/Parse/ParseExpr.cpp
index 490bd5ada62d..1fd98c140e0e 100644
--- a/clang/lib/Parse/ParseExpr.cpp
+++ b/clang/lib/Parse/ParseExpr.cpp
@@ -1334,8 +1334,23 @@ ExprResult Parser::ParseCastExpression(bool isUnaryExpression,
     return ExprError();
   }
 
+  // Check to see whether Res is a function designator only. If it is and we
+  // are compiling for OpenCL, we need to return an error as this implies
+  // that the address of the function is being taken, which is illegal in CL.
+
   // These can be followed by postfix-expr pieces.
-  return ParsePostfixExpressionSuffix(Res);
+  Res = ParsePostfixExpressionSuffix(Res);
+  if (getLangOpts().OpenCL)
+    if (Expr *PostfixExpr = Res.get()) {
+      QualType Ty = PostfixExpr->getType();
+      if (!Ty.isNull() && Ty->isFunctionType()) {
+        Diag(PostfixExpr->getExprLoc(),
+             diag::err_opencl_taking_function_address_parser);
+        return ExprError();
+      }
+    }
+
+  return Res;
 }
 
 /// \brief Once the leading part of a postfix-expression is parsed, this
diff --git a/clang/test/SemaOpenCL/cond.cl b/clang/test/SemaOpenCL/cond.cl
index 8cc4f1e8e910..60f70564d861 100644
--- a/clang/test/SemaOpenCL/cond.cl
+++ b/clang/test/SemaOpenCL/cond.cl
@@ -128,5 +128,5 @@ int foo2(int);
 
 unsigned int ntest12(int2 C)
 {
-  return (unsigned int)(C ? foo1 : foo2); // expected-error {{taking address of function is not allowed}}
+  return (unsigned int)(C ? foo1 : foo2); // expected-error {{taking address of function is not allowed}} expected-error {{taking address of function is not allowed}}
 }
diff --git a/clang/test/SemaOpenCL/func_ptr.cl b/clang/test/SemaOpenCL/func_ptr.cl
index f21a3d3265a5..abeab73a779c 100644
--- a/clang/test/SemaOpenCL/func_ptr.cl
+++ b/clang/test/SemaOpenCL/func_ptr.cl
@@ -11,6 +11,9 @@ void bar()
   foo((void*)foo); // expected-error{{taking address of function is not allowed}}
   foo(&foo); // expected-error{{taking address of function is not allowed}}
 
+  // initializing an array with the address of functions is an error
+  void* vptrarr[2] = {foo, &foo}; // expected-error{{taking address of function is not allowed}} expected-error{{taking address of function is not allowed}}
+
   // just calling a function is correct
   foo(0);
 }