[analyzer] Allow a checker to be hidden even if its package is hidden & enabled.

For example, if 'core.experimental.UnreachableCode' is hidden, it should not be enabled with 'core.experimental'.
Note that this requires llvm commit r126436.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126439 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/Checkers.td b/lib/StaticAnalyzer/Checkers/Checkers.td
index 0320d28..9bcd6c6 100644
--- a/lib/StaticAnalyzer/Checkers/Checkers.td
+++ b/lib/StaticAnalyzer/Checkers/Checkers.td
@@ -137,7 +137,8 @@
 def UnreachableCodeChecker : Checker<"UnreachableCode">,
   InPackage<CoreExperimental>,
   HelpText<"Check unreachable code">,
-  DescFile<"UnreachableCodeChecker.cpp">;
+  DescFile<"UnreachableCodeChecker.cpp">,
+  Hidden; // Must be specified explicitly in order to run.
 
 def IdempotentOperationChecker : Checker<"IdempotentOps">,
   InPackage<CoreExperimental>,
diff --git a/lib/StaticAnalyzer/Checkers/ClangSACheckerProvider.cpp b/lib/StaticAnalyzer/Checkers/ClangSACheckerProvider.cpp
index 94f200f..aefaf54 100644
--- a/lib/StaticAnalyzer/Checkers/ClangSACheckerProvider.cpp
+++ b/lib/StaticAnalyzer/Checkers/ClangSACheckerProvider.cpp
@@ -104,9 +104,10 @@
 
   // Enable/disable all subgroups along with this one.
   if (const short *subGroups = checkName->SubGroups) {
-    for (; *subGroups != -1; ++subGroups)
-      collectCheckers(&CheckNameTable[*subGroups], enable, checkers,
-                      collectHidden && checkName->Hidden);
+    for (; *subGroups != -1; ++subGroups) {
+      const CheckNameOption *sub = &CheckNameTable[*subGroups];
+      collectCheckers(sub, enable, checkers, collectHidden && !sub->Hidden);
+    }
   }
 }