From f6ecadb7aea68fb322bfa1dfce703a24cbd1e395 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Sat, 10 Feb 2018 00:51:00 +0000
Subject: Renable -Wimplicit-fallthrough for PDFium.

Didn't find any bugs, but also doesn't require much boilerplate.

Bug: TODO
Change-Id: I5f30183c55216f1333c79fcb46476d281720873e
Reviewed-on: https://pdfium-review.googlesource.com/26210
Reviewed-by: Lei Zhang <thestig@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
---
 core/fxcrt/fx_extension.cpp    |  3 +++
 core/fxcrt/fx_fallthrough.h    | 20 ++++++++++++++++++++
 core/fxcrt/xml/cxml_parser.cpp |  3 +++
 3 files changed, 26 insertions(+)
 create mode 100644 core/fxcrt/fx_fallthrough.h

(limited to 'core/fxcrt')

diff --git a/core/fxcrt/fx_extension.cpp b/core/fxcrt/fx_extension.cpp
index 62cf8a0e04..371f1b5211 100644
--- a/core/fxcrt/fx_extension.cpp
+++ b/core/fxcrt/fx_extension.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fxcrt/fx_extension.h"
 
+#include "core/fxcrt/fx_fallthrough.h"
+
 #include <algorithm>
 #include <cwctype>
 
@@ -21,6 +23,7 @@ float FXSYS_wcstof(const wchar_t* pwsStr, int32_t iLength, int32_t* pUsedLen) {
   switch (pwsStr[iUsedLen]) {
     case '-':
       bNegtive = true;
+      FX_FALLTHROUGH;
     case '+':
       iUsedLen++;
       break;
diff --git a/core/fxcrt/fx_fallthrough.h b/core/fxcrt/fx_fallthrough.h
new file mode 100644
index 0000000000..5587ee2295
--- /dev/null
+++ b/core/fxcrt/fx_fallthrough.h
@@ -0,0 +1,20 @@
+// Copyright 2018 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CORE_FXCRT_FX_FALLTHROUGH_H_
+#define CORE_FXCRT_FX_FALLTHROUGH_H_
+
+// When clang suggests inserting [[clang::fallthrough]], it first checks if
+// it knows of a macro expanding to it, and if so suggests inserting the
+// macro.  This means that this macro must be used only in code internal
+// to PDFium, so that PDFium's user code doesn't end up getting suggestions
+// for FX_FALLTHROUGH instead of the user-specific fallthrough macro.
+// So do not include this header in any of PDFium's public headers.
+#if defined(__clang__)
+#define FX_FALLTHROUGH [[clang::fallthrough]]
+#else
+#define FX_FALLTHROUGH
+#endif
+
+#endif  // CORE_FXCRT_FX_FALLTHROUGH_H_
diff --git a/core/fxcrt/xml/cxml_parser.cpp b/core/fxcrt/xml/cxml_parser.cpp
index ae5fd6d0fc..64bb0ec530 100644
--- a/core/fxcrt/xml/cxml_parser.cpp
+++ b/core/fxcrt/xml/cxml_parser.cpp
@@ -14,6 +14,7 @@
 #include "core/fxcrt/cfx_utf8decoder.h"
 #include "core/fxcrt/cfx_widetextbuf.h"
 #include "core/fxcrt/fx_extension.h"
+#include "core/fxcrt/fx_fallthrough.h"
 #include "core/fxcrt/xml/cxml_content.h"
 #include "core/fxcrt/xml/cxml_element.h"
 #include "core/fxcrt/xml/cxml_parser.h"
@@ -200,6 +201,7 @@ uint32_t CXML_Parser::GetCharRef() {
             break;
           }
           iState = 1;
+          FX_FALLTHROUGH;
         case 1:
           m_dwIndex++;
           if (ch == ';') {
@@ -226,6 +228,7 @@ uint32_t CXML_Parser::GetCharRef() {
             break;
           }
           iState = 3;
+          FX_FALLTHROUGH;
         case 3:
           m_dwIndex++;
           if (ch == ';') {
-- 
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