[analyzer] -drain is not an alias for -release.

This was previously added to support -[NSAutoreleasePool drain], which
behaves like -release under non-GC and "please collect" under GC. We're
not currently modeling the autorelease pool stack, though, so we can
just take this out entirely.

Fixes PR14927.

llvm-svn: 172444

clang/lib/StaticAnalyzer/Checkers/RetainCountChecker.cpp

@@ -1570,10 +1570,6 @@ void RetainSummaryManager::InitializeMethodSummaries() {
   Summ = getPersistentSummary(NoRet, DecRefMsg);
   addNSObjectMethSummary(GetNullarySelector("release", Ctx), Summ);
 
-  // Create the "drain" selector.
-  Summ = getPersistentSummary(NoRet, isGCEnabled() ? DoNothing : DecRef);
-  addNSObjectMethSummary(GetNullarySelector("drain", Ctx), Summ);
-
   // Create the -dealloc summary.
   Summ = getPersistentSummary(NoRet, Dealloc);
   addNSObjectMethSummary(GetNullarySelector("dealloc", Ctx), Summ);

clang/test/Analysis/retain-release.m

@@ -1938,6 +1938,21 @@ void test_CFPlugInInstanceCreate(CFUUIDRef factoryUUID, CFUUIDRef typeUUID) {
   CFPlugInInstanceCreate(kCFAllocatorDefault, factoryUUID, typeUUID); // no-warning
 }
 
+//===----------------------------------------------------------------------===//
+// PR14927: -drain only has retain-count semantics on NSAutoreleasePool.
+//===----------------------------------------------------------------------===//
+
+@interface PR14927 : NSObject
+- (void)drain;
+@end
+
+void test_drain() {
+  PR14927 *obj = [[PR14927 alloc] init];
+  [obj drain];
+  [obj release]; // no-warning
+}
+
+
 // CHECK:  <key>diagnostics</key>
 // CHECK-NEXT:  <array>
 // CHECK-NEXT:   <dict>