Fix issues reported by Coverity and Visual C++ Analysis.

Throw when (impossible) dynamic_cast failures occur as it isn't reasonable to
recover. That removes 'noexcept' from some methods.
Cast to avoid 'sub-expression overflow' warnings.
Add default initializations and noexcept where safe.
Move DropRenderTarget out of #if to avoid some preprocessor use.

2 files changed, 31 insertions, 21 deletions

diff --git a/win32/PlatWin.cxx b/win32/PlatWin.cxx
index 21a5180ac..8fb415675 100644
--- a/win32/PlatWin.cxx
+++ b/win32/PlatWin.cxx
@@ -408,7 +408,7 @@ public:
 	}
 };
 
-constexpr int stackBufferLength = 1000;
+constexpr int stackBufferLength = 400;
 class TextWide : public VarBuffer<wchar_t, stackBufferLength> {
 public:
 	int tlen;	// Using int instead of size_t as most Win32 APIs take int.
@@ -471,7 +471,7 @@ class SurfaceGDI : public Surface {
 	void PenColour(ColourAlpha fore, XYPOSITION widthStroke) noexcept;
 
 	void BrushColour(ColourAlpha back) noexcept;
-	void SetFont(const Font *font_) noexcept;
+	void SetFont(const Font *font_);
 	void Clear() noexcept;
 
 public:
@@ -663,9 +663,12 @@ void SurfaceGDI::BrushColour(ColourAlpha back) noexcept {
 	brushOld = SelectBrush(hdc, brush);
 }
 
-void SurfaceGDI::SetFont(const Font *font_) noexcept {
+void SurfaceGDI::SetFont(const Font *font_) {
 	const FontGDI *pfm = dynamic_cast<const FontGDI *>(font_);
 	PLATFORM_ASSERT(pfm);
+	if (!pfm) {
+		throw std::runtime_error("SurfaceGDI::SetFont: wrong Font type.");
+	}
 	if (fontOld) {
 		SelectFont(hdc, pfm->hfont);
 	} else {
@@ -990,7 +993,7 @@ void SurfaceGDI::DrawRGBAImage(PRectangle rc, int width, int height, const unsig
 		const SIZE size { width, height };
 		DIBSection section(hdc, size);
 		if (section) {
-			RGBAImage::BGRAFromRGBA(section.Bytes(), pixelsImage, width * height);
+			RGBAImage::BGRAFromRGBA(section.Bytes(), pixelsImage, static_cast<size_t>(width) * height);
 			AlphaBlend(hdc, static_cast<int>(rc.left), static_cast<int>(rc.top),
 				static_cast<int>(rc.Width()), static_cast<int>(rc.Height()), section.DC(),
 				0, 0, width, height, mergeAlpha);
@@ -1314,7 +1317,7 @@ class SurfaceD2D : public Surface {
 	int logPixelsY = USER_DEFAULT_SCREEN_DPI;
 
 	void Clear() noexcept;
-	void SetFont(const Font *font_) noexcept;
+	void SetFont(const Font *font_);
 	HRESULT GetBitmap(ID2D1Bitmap **ppBitmap);
 
 public:
@@ -1489,9 +1492,12 @@ void SurfaceD2D::D2DPenColourAlpha(ColourAlpha fore) noexcept {
 	}
 }
 
-void SurfaceD2D::SetFont(const Font *font_) noexcept {
+void SurfaceD2D::SetFont(const Font *font_) {
 	const FontDirectWrite *pfm = dynamic_cast<const FontDirectWrite *>(font_);
 	PLATFORM_ASSERT(pfm);
+	if (!pfm) {
+		throw std::runtime_error("SurfaceD2D::SetFont: wrong Font type.");
+	}
 	pTextFormat = pfm->pTextFormat;
 	yAscent = pfm->yAscent;
 	yDescent = pfm->yDescent;
@@ -1657,6 +1663,9 @@ void SurfaceD2D::FillRectangleAligned(PRectangle rc, Fill fill) {
 void SurfaceD2D::FillRectangle(PRectangle rc, Surface &surfacePattern) {
 	SurfaceD2D *psurfOther = dynamic_cast<SurfaceD2D *>(&surfacePattern);
 	PLATFORM_ASSERT(psurfOther);
+	if (!psurfOther) {
+		throw std::runtime_error("SurfaceD2D::FillRectangle: wrong Surface type.");
+	}
 	ID2D1Bitmap *pBitmap = nullptr;
 	HRESULT hr = psurfOther->GetBitmap(&pBitmap);
 	if (SUCCEEDED(hr) && pBitmap) {
@@ -2083,6 +2092,9 @@ void ScreenLineLayout::FillTextLayoutFormats(const IScreenLine *screenLine, IDWr
 
 		const FontDirectWrite *pfm =
 			dynamic_cast<const FontDirectWrite *>(screenLine->FontOfPosition(bytePosition));
+		if (!pfm) {
+			throw std::runtime_error("FillTextLayoutFormats: wrong Font type.");
+		}
 
 		const unsigned int fontFamilyNameSize = pfm->pTextFormat->GetFontFamilyNameLength();
 		std::wstring fontFamilyName(fontFamilyNameSize, 0);
@@ -2141,7 +2153,7 @@ ScreenLineLayout::ScreenLineLayout(const IScreenLine *screenLine) {
 	// Get textFormat
 	const FontDirectWrite *pfm = dynamic_cast<const FontDirectWrite *>(screenLine->FontOfPosition(0));
 
-	if (!pIDWriteFactory || !pfm->pTextFormat) {
+	if (!pIDWriteFactory || !pfm || !pfm->pTextFormat) {
 		return;
 	}
 
@@ -2214,7 +2226,7 @@ size_t ScreenLineLayout::PositionFromX(XYPOSITION xDistance, bool charPosition)
 	if (charPosition) {
 		pos = isTrailingHit ? hitTestMetrics.textPosition : caretMetrics.textPosition;
 	} else {
-		pos = isTrailingHit ? hitTestMetrics.textPosition + hitTestMetrics.length : caretMetrics.textPosition;
+		pos = isTrailingHit ? static_cast<size_t>(hitTestMetrics.textPosition) + hitTestMetrics.length : caretMetrics.textPosition;
 	}
 
 	// Get the character position in original string
diff --git a/win32/ScintillaWin.cxx b/win32/ScintillaWin.cxx
index 4e6fc9b0d..810682df4 100644
--- a/win32/ScintillaWin.cxx
+++ b/win32/ScintillaWin.cxx
@@ -363,8 +363,8 @@ class ScintillaWin :
 	void Finalise() override;
 #if defined(USE_D2D)
 	void EnsureRenderTarget(HDC hdc);
-	void DropRenderTarget();
 #endif
+	void DropRenderTarget() noexcept;
 	HWND MainHWND() const noexcept;
 
 	static sptr_t DirectFunction(
@@ -394,7 +394,7 @@ class ScintillaWin :
 	sptr_t HandleCompositionWindowed(uptr_t wParam, sptr_t lParam);
 	sptr_t HandleCompositionInline(uptr_t wParam, sptr_t lParam);
 	static bool KoreanIME() noexcept;
-	void MoveImeCarets(Sci::Position offset);
+	void MoveImeCarets(Sci::Position offset) noexcept;
 	void DrawImeIndicator(int indicator, Sci::Position len);
 	void SetCandidateWindowPos();
 	void SelectionToHangul();
@@ -602,9 +602,7 @@ void ScintillaWin::Finalise() {
 		FineTickerCancel(tr);
 	}
 	SetIdle(false);
-#if defined(USE_D2D)
 	DropRenderTarget();
-#endif
 	::RevokeDragDrop(MainHWND());
 	if (SUCCEEDED(hrOle)) {
 		::OleUninitialize();
@@ -627,7 +625,7 @@ void ScintillaWin::EnsureRenderTarget(HDC hdc) {
 
 		// Create a Direct2D render target.
 #if 1
-		D2D1_RENDER_TARGET_PROPERTIES drtp;
+		D2D1_RENDER_TARGET_PROPERTIES drtp {};
 		drtp.type = D2D1_RENDER_TARGET_TYPE_DEFAULT;
 		drtp.pixelFormat.format = DXGI_FORMAT_UNKNOWN;
 		drtp.pixelFormat.alphaMode = D2D1_ALPHA_MODE_UNKNOWN;
@@ -651,7 +649,7 @@ void ScintillaWin::EnsureRenderTarget(HDC hdc) {
 			}
 
 		} else {
-			D2D1_HWND_RENDER_TARGET_PROPERTIES dhrtp;
+			D2D1_HWND_RENDER_TARGET_PROPERTIES dhrtp {};
 			dhrtp.hwnd = hw;
 			dhrtp.pixelSize = size;
 			dhrtp.presentOptions = (technology == SC_TECHNOLOGY_DIRECTWRITERETAIN) ?
@@ -690,12 +688,14 @@ void ScintillaWin::EnsureRenderTarget(HDC hdc) {
 		}
 	}
 }
+#endif
 
-void ScintillaWin::DropRenderTarget() {
-	ReleaseUnknown(pRenderTarget);
-}
 
+void ScintillaWin::DropRenderTarget() noexcept {
+#if defined(USE_D2D)
+	ReleaseUnknown(pRenderTarget);
 #endif
+}
 
 HWND ScintillaWin::MainHWND() const noexcept {
 	return HwndFromWindow(wMain);
@@ -991,7 +991,7 @@ sptr_t ScintillaWin::HandleCompositionWindowed(uptr_t wParam, sptr_t lParam) {
 
 			// Set new position after converted
 			const Point pos = PointMainCaret();
-			COMPOSITIONFORM CompForm;
+			COMPOSITIONFORM CompForm {};
 			CompForm.dwStyle = CFS_POINT;
 			CompForm.ptCurrentPos = POINTFromPoint(pos);
 			::ImmSetCompositionWindow(imc.hIMC, &CompForm);
@@ -1006,7 +1006,7 @@ bool ScintillaWin::KoreanIME() noexcept {
 	return codePage == 949 || codePage == 1361;
 }
 
-void ScintillaWin::MoveImeCarets(Sci::Position offset) {
+void ScintillaWin::MoveImeCarets(Sci::Position offset) noexcept {
 	// Move carets relatively by bytes.
 	for (size_t r=0; r<sel.Count(); r++) {
 		const Sci::Position positionInsert = sel.Range(r).Start().Position();
@@ -1835,9 +1835,7 @@ sptr_t ScintillaWin::SciMessage(unsigned int iMessage, uptr_t wParam, sptr_t lPa
 				} else {
 					bidirectional = EditModel::Bidirectional::bidiDisabled;
 				}
-#if defined(USE_D2D)
 				DropRenderTarget();
-#endif
 				technology = technologyNew;
 				// Invalidate all cached information including layout.
 				DropGraphics();