From 4e597c8fd5d604273266ea19a1074a2c870ba224 Mon Sep 17 00:00:00 2001
From: tsepez <tsepez@chromium.org>
Date: Mon, 7 Nov 2016 15:16:01 -0800
Subject: Force compiler to deduce src type for checked_cast<dst, src>.

Otherwise, we might be silently doing an unsafe cast before
applying the check if the actual argument doesn't match the
exact src type.

Review-Url: https://codereview.chromium.org/2484953003
---
 core/fpdfapi/parser/cpdf_parser.cpp | 6 ++----
 core/fpdfdoc/cpdf_formfield.cpp     | 2 +-
 fpdfsdk/fpdfview.cpp                | 6 ++----
 third_party/base/stl_util.h         | 2 +-
 4 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/core/fpdfapi/parser/cpdf_parser.cpp b/core/fpdfapi/parser/cpdf_parser.cpp
index cf23ec7cd7..ed20cf73f4 100644
--- a/core/fpdfapi/parser/cpdf_parser.cpp
+++ b/core/fpdfapi/parser/cpdf_parser.cpp
@@ -1015,10 +1015,8 @@ bool CPDF_Parser::LoadCrossRefV5(FX_FILESIZE* pos, bool bMainXRef) {
     if (startnum < 0)
       continue;
 
-    m_dwXrefStartObjNum =
-        pdfium::base::checked_cast<uint32_t, int32_t>(startnum);
-    uint32_t count =
-        pdfium::base::checked_cast<uint32_t, int32_t>(arrIndex[i].second);
+    m_dwXrefStartObjNum = pdfium::base::checked_cast<uint32_t>(startnum);
+    uint32_t count = pdfium::base::checked_cast<uint32_t>(arrIndex[i].second);
     FX_SAFE_UINT32 dwCaculatedSize = segindex;
     dwCaculatedSize += count;
     dwCaculatedSize *= totalWidth;
diff --git a/core/fpdfdoc/cpdf_formfield.cpp b/core/fpdfdoc/cpdf_formfield.cpp
index e2240c9f2f..8170b7fcbf 100644
--- a/core/fpdfdoc/cpdf_formfield.cpp
+++ b/core/fpdfdoc/cpdf_formfield.cpp
@@ -682,7 +682,7 @@ int CPDF_FormField::InsertOption(CFX_WideString csOptLabel,
     m_pDict->SetFor("Opt", pOpt);
   }
 
-  int iCount = pdfium::base::checked_cast<int, size_t>(pOpt->GetCount());
+  int iCount = pdfium::base::checked_cast<int>(pOpt->GetCount());
   if (index >= iCount) {
     pOpt->AddString(csStr);
     index = iCount;
diff --git a/fpdfsdk/fpdfview.cpp b/fpdfsdk/fpdfview.cpp
index 9142dc78c9..334c14cd45 100644
--- a/fpdfsdk/fpdfview.cpp
+++ b/fpdfsdk/fpdfview.cpp
@@ -192,8 +192,7 @@ bool CPDF_CustomAccess::ReadBlock(void* buffer,
   if (offset < 0)
     return false;
 
-  FX_SAFE_FILESIZE newPos =
-      pdfium::base::checked_cast<FX_FILESIZE, size_t>(size);
+  FX_SAFE_FILESIZE newPos = pdfium::base::checked_cast<FX_FILESIZE>(size);
   newPos += offset;
   if (!newPos.IsValid() ||
       newPos.ValueOrDie() > static_cast<FX_FILESIZE>(m_FileAccess.m_FileLen)) {
@@ -388,8 +387,7 @@ class CMemFile final : public IFX_SeekableReadStream {
     if (offset < 0) {
       return false;
     }
-    FX_SAFE_FILESIZE newPos =
-        pdfium::base::checked_cast<FX_FILESIZE, size_t>(size);
+    FX_SAFE_FILESIZE newPos = pdfium::base::checked_cast<FX_FILESIZE>(size);
     newPos += offset;
     if (!newPos.IsValid() || newPos.ValueOrDie() > m_size) {
       return false;
diff --git a/third_party/base/stl_util.h b/third_party/base/stl_util.h
index 0bf442c316..795414b59f 100644
--- a/third_party/base/stl_util.h
+++ b/third_party/base/stl_util.h
@@ -41,7 +41,7 @@ class FakeUniquePtr : public std::unique_ptr<T> {
 // size_t size() method return values will be checked.
 template <typename ResultType, typename Collection>
 ResultType CollectionSize(const Collection& collection) {
-  return pdfium::base::checked_cast<ResultType, size_t>(collection.size());
+  return pdfium::base::checked_cast<ResultType>(collection.size());
 }
 
 // Track the addition of an object to a set, removing it automatically when
-- 
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