Fix unreachable-break-or-return issue in proxygen/lib/http/codec/HTTPCodec.h +5

Summary:
LLVM has two warnings `-Wunreachable-code-return` and `-Wunreachable-code-break` which identify `return` and `break` statements that cannot be reached. These compromise readability, can be misleading, and may identify bugs. This diff removes such statements.

`break` was often used defensively in `switch` statements. We now have `-Wimplicit-fallthrough` [enabled globally](https://fb.workplace.com/groups/fbcode/posts/8021835991186503), which replaces this inexact practice with a compiler guarantee.

The compiler used to be less intelligent and would throw an error if a function didn't return the correct type after a `throw` statement. The compiler is smarter now, so this code is unnecessary. `-Wreturn-type` is enabled globally and prevents functions from ending without an appropriate return.

 - If you approve of this diff, please use the "Accept & Ship" button :-)

Reviewed By: dtolnay

Differential Revision: D79967259

fbshipit-source-id: 37b547b324af1db83599ccc78a927d4be77ec6f3

Author: r-barnes

third-party/proxygen/src/proxygen/lib/http/codec/HTTPCodec.h

@@ -386,7 +386,6 @@ class HTTPCodec {
         [[fallthrough]];
       default:
         LOG(FATAL) << "Unreachable";
-        return std::numeric_limits<size_t>::max();
     }
   }
 

third-party/proxygen/src/proxygen/lib/http/codec/HTTPCodecFactory.cpp

@@ -29,7 +29,6 @@ std::unique_ptr<HTTPCodec> HTTPCodecFactory::getCodec(
     }
     default:
       LOG(FATAL) << "Unreachable";
-      return nullptr;
   }
 }
 

third-party/proxygen/src/proxygen/lib/http/codec/compress/QPACKStaticHeaderTable.cpp

@@ -141,7 +141,6 @@ namespace proxygen {
 bool QPACKStaticHeaderTable::isHeaderCodeInTableWithNonEmptyValue(
     HTTPHeaderCode /*headerCode*/) {
   LOG(FATAL) << __func__ << " not supported for QPACK";
-  return false;
 }
 
 const StaticHeaderTable& QPACKStaticHeaderTable::get() {

third-party/proxygen/src/proxygen/lib/http/codec/compress/experimental/simulator/CompressionSimulator.cpp

@@ -279,7 +279,6 @@ unique_ptr<CompressionScheme> CompressionSimulator::makeScheme() {
       return make_unique<HPACKScheme>(this, params_.tableSize);
   }
   LOG(FATAL) << "Bad scheme";
-  return nullptr;
 }
 
 std::pair<FrameFlags, unique_ptr<IOBuf>> CompressionSimulator::encode(

third-party/proxygen/src/proxygen/lib/http/codec/test/HQCodecTest.cpp

@@ -905,7 +905,6 @@ std::string frameParamsToTestName(
       break;
     default:
       LOG(FATAL) << "Unknown Codec Type";
-      break;
   }
   switch (info.param.frameType) {
     case FrameType::DATA:
@@ -982,7 +981,6 @@ TEST_P(HQCodecTestFrameAllowed, FrameAllowedOnCodec) {
       break;
     default:
       CHECK(false);
-      break;
   }
   expectedFrames += GetParam().allowed ? 1 : 0;
   EXPECT_EQ(callbacks_.headerFrames, expectedFrames);
@@ -1015,7 +1013,6 @@ TEST_P(HQCodecTestFrameAllowed, FrameAllowedOnCodec) {
         break;
       default:
         CHECK(false);
-        break;
     }
     EXPECT_EQ(lenBefore, lenAfter);
     EXPECT_EQ(callbacks_.headerFrames, expectedFrames);