Fix "control reaches end of non-void function" warnings on ppc64le

[zhaomo]

Summary

Warnings can be found here: https://lab.llvm.org/buildbot/#/builders/76/builds/2640

[zhaomo]

Warnings can be found here: https://lab.llvm.org/buildbot/#/builders/76/builds/2640

[ymandel]

Thanks!

[ymandel]

Actually, the removal of the default case in the switch gives this warning:
...llvm-project/clang/lib/ASTMatchers/GtestMatchers.cpp:102:11: warning: enumeration value 'Assert' not handled in switch [-Wswitch]

I'll reinstate the default case before comitting the patch.

clang/lib/ASTMatchers/GtestMatchers.cpp

case GtestCmp::Ge:
     return functionDecl(hasName("::testing::internal::CmpHelperGE"));
   case GtestCmp::Gt:
     return functionDecl(hasName("::testing::internal::CmpHelperGT"));
   case GtestCmp::Le:
     return functionDecl(hasName("::testing::internal::CmpHelperLE"));
   case GtestCmp::Lt:
     return functionDecl(hasName("::testing::internal::CmpHelperLT"));
   }
+  llvm_unreachable("Unhandled GtestCmp enum");
 }
 
 static llvm::StringRef getMacroTypeName(MacroType Macro) {
   switch (Macro) {
   case MacroType::Expect:
     return "EXPECT";
   case MacroType::Assert:
     return "ASSERT";
   case MacroType::On:
     return "ON";
   }
+  llvm_unreachable("Unhandled MacroType enum");
 }
 
 static llvm::StringRef getComparisonTypeName(GtestCmp Cmp) {
   switch (Cmp) {
   case GtestCmp::Eq:
     return "EQ";
   case GtestCmp::Ne:
     return "NE";
   case GtestCmp::Ge:
     return "GE";
   case GtestCmp::Gt:
     return "GT";
   case GtestCmp::Le:
     return "LE";
   case GtestCmp::Lt:
     return "LT";
   }
+  llvm_unreachable("Unhandled GtestCmp enum");
 }
 
 static std::string getMacroName(MacroType Macro, GtestCmp Cmp) {
   return (getMacroTypeName(Macro) + "_" + getComparisonTypeName(Cmp)).str();
 }
 
 static std::string getMacroName(MacroType Macro, llvm::StringRef Operation) {
   return (getMacroTypeName(Macro) + "_" + Operation).str();
 }
 
 // Under the hood, ON_CALL is expanded to a call to `InternalDefaultActionSetAt`
 // to set a default action spec to the underlying function mocker, while
 // EXPECT_CALL is expanded to a call to `InternalExpectedAt` to set a new
 // expectation spec.
 static llvm::StringRef getSpecSetterName(MacroType Macro) {
   switch (Macro) {
   case MacroType::On:
     return "InternalDefaultActionSetAt";
   case MacroType::Expect:
     return "InternalExpectedAt";
   default:
     llvm_unreachable("Unhandled MacroType enum");
   }
+  llvm_unreachable("Unhandled MacroType enum");
 }
 
 // In general, AST matchers cannot match calls to macros. However, we can
 // simulate such matches if the macro definition has identifiable elements that
 // themselves can be matched. In that case, we can match on those elements and
 // then check that the match occurs within an expansion of the desired
 // macro. The more uncommon the identified elements, the more efficient this
 // process will be.
gtestCallInternal(MacroType Macro, StatementMatcher MockCall, MockArgs Args) {
   case MockArgs::Some:
     return cxxMemberCallExpr(
         isExpandedFromMacro(getMacroName(Macro, "CALL")),
         callee(functionDecl(hasName(getSpecSetterName(Macro)))),
         onImplicitObjectArgument(ignoringImplicit(cxxOperatorCallExpr(
             hasOverloadedOperatorName("()"), argumentCountIs(3),
             hasArgument(0, ignoringImplicit(MockCall))))));
   }
+  llvm_unreachable("Unhandled MockArgs enum");
 }
 
 static internal::BindableMatcher<Stmt>
 gtestCallInternal(MacroType Macro, StatementMatcher MockObject,
                   llvm::StringRef MockMethodName, MockArgs Args) {
   return gtestCallInternal(
       Macro,
       cxxMemberCallExpr(