From f2a27f40d658446fd544f6f4f226b1e1ea6bb1c4 Mon Sep 17 00:00:00 2001
From: Argyrios Kyrtzidis <akyrtzi@gmail.com>
Date: Thu, 14 Jul 2011 23:32:04 +0000
Subject: [PATCH] [arcmt] Don't remove retains/releases on a global variable,
 flag them with errors. rdar://9402555.

llvm-svn: 135213
---
 clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp |  9 +++++++++
 clang/lib/ARCMigrate/TransUnbridgedCasts.cpp       | 11 -----------
 clang/lib/ARCMigrate/Transforms.cpp                | 11 +++++++++++
 clang/lib/ARCMigrate/Transforms.h                  |  2 ++
 clang/test/ARCMT/checking.m                        |  6 ++++++
 5 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp b/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
index 4eeb47437e34..c72312b2600b 100644
--- a/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
+++ b/clang/lib/ARCMigrate/TransRetainReleaseDealloc.cpp
@@ -78,6 +78,15 @@ public:
             Pass.TA.reportError(err, rec->getLocStart());
             return true;
           }
+
+          if (isGlobalVar(rec) &&
+              (E->getMethodFamily() != OMF_retain || isRemovable(E))) {
+            std::string err = "it is not safe to remove '";
+            err += E->getSelector().getAsString() + "' message on "
+                "a global variable";
+            Pass.TA.reportError(err, rec->getLocStart());
+            return true;
+          }
         }
     case OMF_dealloc:
       break;
diff --git a/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp b/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
index 6513d98c9297..1cacd6d84e6d 100644
--- a/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
+++ b/clang/lib/ARCMigrate/TransUnbridgedCasts.cpp
@@ -193,17 +193,6 @@ private:
         return true;
     return false;
   }
-
-  static bool isGlobalVar(Expr *E) {
-    E = E->IgnoreParenCasts();
-    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
-      return DRE->getDecl()->getDeclContext()->isFileContext();
-    if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
-      return isGlobalVar(condOp->getTrueExpr()) &&
-             isGlobalVar(condOp->getFalseExpr());
-
-    return false;  
-  }
 };
 
 } // end anonymous namespace
diff --git a/clang/lib/ARCMigrate/Transforms.cpp b/clang/lib/ARCMigrate/Transforms.cpp
index 7a439d95e3ad..7bd95e54bc27 100644
--- a/clang/lib/ARCMigrate/Transforms.cpp
+++ b/clang/lib/ARCMigrate/Transforms.cpp
@@ -152,6 +152,17 @@ bool trans::hasSideEffects(Expr *E, ASTContext &Ctx) {
   return true;
 }
 
+bool trans::isGlobalVar(Expr *E) {
+  E = E->IgnoreParenCasts();
+  if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E))
+    return DRE->getDecl()->getDeclContext()->isFileContext();
+  if (ConditionalOperator *condOp = dyn_cast<ConditionalOperator>(E))
+    return isGlobalVar(condOp->getTrueExpr()) &&
+           isGlobalVar(condOp->getFalseExpr());
+
+  return false;  
+}
+
 namespace {
 
 class ReferenceClear : public RecursiveASTVisitor<ReferenceClear> {
diff --git a/clang/lib/ARCMigrate/Transforms.h b/clang/lib/ARCMigrate/Transforms.h
index 00ff733f47ea..b47d6d8e9b8b 100644
--- a/clang/lib/ARCMigrate/Transforms.h
+++ b/clang/lib/ARCMigrate/Transforms.h
@@ -54,6 +54,8 @@ bool canApplyWeak(ASTContext &Ctx, QualType type);
 SourceLocation findLocationAfterSemi(SourceLocation loc, ASTContext &Ctx);
 
 bool hasSideEffects(Expr *E, ASTContext &Ctx);
+bool isGlobalVar(Expr *E);
+
 
 template <typename BODY_TRANS>
 class BodyTransform : public RecursiveASTVisitor<BodyTransform<BODY_TRANS> > {
diff --git a/clang/test/ARCMT/checking.m b/clang/test/ARCMT/checking.m
index 7ab54ceb05d5..2e4ec122d64c 100644
--- a/clang/test/ARCMT/checking.m
+++ b/clang/test/ARCMT/checking.m
@@ -36,10 +36,16 @@ struct UnsafeS {
 - (oneway void)release { } // expected-error {{ARC forbids implementation}}
 @end
 
+id global_foo;
+
 void test1(A *a, BOOL b, struct UnsafeS *unsafeS) {
   [unsafeS->unsafeObj retain]; // expected-error {{it is not safe to remove 'retain' message on an __unsafe_unretained type}} \
                                // expected-error {{ARC forbids explicit message send}}
   id foo = [unsafeS->unsafeObj retain]; // no warning.
+  [global_foo retain]; // expected-error {{it is not safe to remove 'retain' message on a global variable}} \
+                       // expected-error {{ARC forbids explicit message send}}
+  [global_foo release]; // expected-error {{it is not safe to remove 'release' message on a global variable}} \
+                        // expected-error {{ARC forbids explicit message send}}
   [a dealloc];
   [a retain];
   [a retainCount]; // expected-error {{ARC forbids explicit message send of 'retainCount'}}