Re-enable several MSVC warnings

Re-enable the following warnings:
 4245: signed/unsigned conversion mismatch;
 4310: cast may truncate data;
 4389: operator on signed/unsigned mismatch;
 4701: use potentially uninitialized local variable;
 4706: assignment within conditional expression

Clean up the code to avoid those warnings.

BUG=pdfium:29
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1801383002 .

7 files changed, 27 insertions, 22 deletions

diff --git a/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp b/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
index 42315dad53..2fddf10a78 100644
--- a/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
+++ b/core/fpdfapi/fpdf_edit/fpdf_edit_doc.cpp
@@ -924,7 +924,7 @@ CPDF_Font* CPDF_Document::AddFont(CFX_Font* pFont, int charset, FX_BOOL bVert) {
     pFontDict = new CPDF_Dictionary;
     CFX_ByteString cmap;
     CFX_ByteString ordering;
-    int supplement;
+    int supplement = 0;
     CPDF_Array* pWidthArray = new CPDF_Array;
     switch (charset) {
       case FXFONT_CHINESEBIG5_CHARSET:
@@ -936,7 +936,8 @@ CPDF_Font* CPDF_Document::AddFont(CFX_Font* pFont, int charset, FX_BOOL bVert) {
         break;
       case FXFONT_GB2312_CHARSET:
         cmap = bVert ? "GBK-EUC-V" : "GBK-EUC-H";
-        ordering = "GB1", supplement = 2;
+        ordering = "GB1";
+        supplement = 2;
         pWidthArray->AddInteger(7716);
         _InsertWidthArray1(pFont, pEncoding.get(), 0x20, 0x20, pWidthArray);
         pWidthArray->AddInteger(814);
diff --git a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
index 1295c624ad..f370b86049 100644
--- a/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
+++ b/core/fpdfapi/fpdf_font/fpdf_font_cid.cpp
@@ -1584,7 +1584,8 @@ void CPDF_CIDFont::LoadMetricsArray(CPDF_Array* pArray,
                                     int nElements) {
   int width_status = 0;
   int iCurElement = 0;
-  int first_code = 0, last_code;
+  int first_code = 0;
+  int last_code = 0;
   FX_DWORD count = pArray->GetCount();
   for (FX_DWORD i = 0; i < count; i++) {
     CPDF_Object* pObj = pArray->GetElementValue(i);
diff --git a/core/fpdfapi/fpdf_page/cpdf_page.cpp b/core/fpdfapi/fpdf_page/cpdf_page.cpp
index 0da5452969..2c01cd5573 100644
--- a/core/fpdfapi/fpdf_page/cpdf_page.cpp
+++ b/core/fpdfapi/fpdf_page/cpdf_page.cpp
@@ -140,7 +140,12 @@ void CPDF_Page::GetDisplayMatrix(CFX_Matrix& matrix,
     return;
   }
   CFX_Matrix display_matrix;
-  int x0, y0, x1, y1, x2, y2;
+  int x0 = 0;
+  int y0 = 0;
+  int x1 = 0;
+  int y1 = 0;
+  int x2 = 0;
+  int y2 = 0;
   iRotate %= 4;
   switch (iRotate) {
     case 0:
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp b/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
index c9f05ac5ab..87ed09735a 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_parser_old.cpp
@@ -41,11 +41,11 @@ CPDF_StreamParser::~CPDF_StreamParser() {
   }
 }
 
-FX_DWORD _DecodeAllScanlines(ICodec_ScanlineDecoder* pDecoder,
-                             uint8_t*& dest_buf,
-                             FX_DWORD& dest_size) {
+FX_DWORD DecodeAllScanlines(ICodec_ScanlineDecoder* pDecoder,
+                            uint8_t*& dest_buf,
+                            FX_DWORD& dest_size) {
   if (!pDecoder) {
-    return (FX_DWORD)-1;
+    return static_cast<FX_DWORD>(-1);
   }
   int ncomps = pDecoder->CountComps();
   int bpc = pDecoder->GetBPC();
@@ -54,7 +54,7 @@ FX_DWORD _DecodeAllScanlines(ICodec_ScanlineDecoder* pDecoder,
   int pitch = (width * ncomps * bpc + 7) / 8;
   if (height == 0 || pitch > (1 << 30) / height) {
     delete pDecoder;
-    return -1;
+    return static_cast<FX_DWORD>(-1);
   }
   dest_buf = FX_Alloc2D(uint8_t, pitch, height);
   dest_size = pitch * height;  // Safe since checked alloc returned.
@@ -88,7 +88,7 @@ FX_DWORD PDF_DecodeInlineStream(const uint8_t* src_buf,
   if (decoder == "CCITTFaxDecode" || decoder == "CCF") {
     ICodec_ScanlineDecoder* pDecoder =
         FPDFAPI_CreateFaxDecoder(src_buf, limit, width, height, pParam);
-    return _DecodeAllScanlines(pDecoder, dest_buf, dest_size);
+    return DecodeAllScanlines(pDecoder, dest_buf, dest_size);
   }
   if (decoder == "ASCII85Decode" || decoder == "A85") {
     return A85Decode(src_buf, limit, dest_buf, dest_size);
@@ -109,7 +109,7 @@ FX_DWORD PDF_DecodeInlineStream(const uint8_t* src_buf,
         CPDF_ModuleMgr::Get()->GetJpegModule()->CreateDecoder(
             src_buf, limit, width, height, 0,
             pParam ? pParam->GetIntegerBy("ColorTransform", 1) : 1);
-    return _DecodeAllScanlines(pDecoder, dest_buf, dest_size);
+    return DecodeAllScanlines(pDecoder, dest_buf, dest_size);
   }
   if (decoder == "RunLengthDecode" || decoder == "RL") {
     return RunLengthDecode(src_buf, limit, dest_buf, dest_size);
diff --git a/core/fpdfapi/fpdf_parser/cpdf_parser.cpp b/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
index c9b8583d16..3ee53e6cf9 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_parser.cpp
@@ -1538,9 +1538,8 @@ CPDF_Parser::Error CPDF_Parser::StartAsyncParse(IFX_FileRead* pFileAccess) {
   FX_FILESIZE dwFirstXRefOffset = m_pSyntax->SavePos();
 
   FX_BOOL bXRefRebuilt = FALSE;
-  FX_BOOL bLoadV4 = FALSE;
-  if (!(bLoadV4 = LoadCrossRefV4(dwFirstXRefOffset, 0, FALSE)) &&
-      !LoadCrossRefV5(&dwFirstXRefOffset, TRUE)) {
+  FX_BOOL bLoadV4 = LoadCrossRefV4(dwFirstXRefOffset, 0, FALSE);
+  if (!bLoadV4 && !LoadCrossRefV5(&dwFirstXRefOffset, TRUE)) {
     if (!RebuildCrossRef())
       return FORMAT_ERROR;
 
diff --git a/core/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp b/core/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
index f7fc3099fc..c91e99b9cb 100644
--- a/core/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
+++ b/core/fpdfapi/fpdf_parser/fpdf_parser_decode.cpp
@@ -177,14 +177,14 @@ FX_DWORD RunLengthDecode(const uint8_t* src_buf,
       old = dest_size;
       dest_size += src_buf[i] + 1;
       if (dest_size < old) {
-        return (FX_DWORD)-1;
+        return static_cast<FX_DWORD>(-1);
       }
       i += src_buf[i] + 2;
     } else if (src_buf[i] > 128) {
       old = dest_size;
       dest_size += 257 - src_buf[i];
       if (dest_size < old) {
-        return (FX_DWORD)-1;
+        return static_cast<FX_DWORD>(-1);
       }
       i += 2;
     } else {
@@ -192,7 +192,7 @@ FX_DWORD RunLengthDecode(const uint8_t* src_buf,
     }
   }
   if (dest_size >= _STREAM_MAX_SIZE_) {
-    return -1;
+    return static_cast<FX_DWORD>(-1);
   }
   dest_buf = FX_Alloc(uint8_t, dest_size);
   i = 0;
diff --git a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
index fe72bb3aee..6741d1a70b 100644
--- a/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
+++ b/core/fpdfapi/fpdf_render/fpdf_render_text.cpp
@@ -140,12 +140,12 @@ CFX_GlyphBitmap* CPDF_Type3Cache::RenderGlyph(CPDF_Type3Glyphs* pSize,
   text_matrix.Set(pMatrix->a, pMatrix->b, pMatrix->c, pMatrix->d, 0, 0);
   image_matrix.Concat(text_matrix);
   CFX_DIBitmap* pResBitmap = NULL;
-  int left, top;
+  int left = 0;
+  int top = 0;
   if (FXSYS_fabs(image_matrix.b) < FXSYS_fabs(image_matrix.a) / 100 &&
       FXSYS_fabs(image_matrix.c) < FXSYS_fabs(image_matrix.d) / 100) {
-    int top_line, bottom_line;
-    top_line = _DetectFirstLastScan(pBitmap, TRUE);
-    bottom_line = _DetectFirstLastScan(pBitmap, FALSE);
+    int top_line = _DetectFirstLastScan(pBitmap, TRUE);
+    int bottom_line = _DetectFirstLastScan(pBitmap, FALSE);
     if (top_line == 0 && bottom_line == pBitmap->GetHeight() - 1) {
       FX_FLOAT top_y = image_matrix.d + image_matrix.f;
       FX_FLOAT bottom_y = image_matrix.f;
@@ -167,7 +167,6 @@ CFX_GlyphBitmap* CPDF_Type3Cache::RenderGlyph(CPDF_Type3Glyphs* pSize,
       } else {
         left = FXSYS_round(image_matrix.e);
       }
-    } else {
     }
   }
   if (!pResBitmap) {