[Libreoffice-commits] core.git: include/o3tl vcl/win

[Stephan Bergmann (via logerrit)]

 include/o3tl/safeint.hxx           |    5 +++++
 vcl/win/gdi/DWriteTextRenderer.cxx |    5 ++++-
 vcl/win/gdi/winlayout.cxx          |    7 +++++--
 3 files changed, 14 insertions(+), 3 deletions(-)

New commits:
commit b1404b5919f8c18bde715f68b229d2c030de5b2a
Author:     Stephan Bergmann <sbergman at redhat.com>
AuthorDate: Wed Nov 25 11:06:00 2020 +0100
Commit:     Stephan Bergmann <sbergman at redhat.com>
CommitDate: Wed Nov 25 14:08:20 2020 +0100

    -Wc++11-narrowing (clang-cl)
    
    MSVC seems not to mind, but a Windows 64-bit build with clang-cl fails with
    "error: non-constant-expression cannot be narrowed from type 'tools::Long' (aka
    'long long') to 'LONG' (aka 'long') in initializer list".  But adding explicit
    casts would have the downside of preventing tools like
    -fsanitize=implict-conversion (if we ever use that on Windows) from detecting
    truncation, so introduce o3tl::narrowing.
    
    Change-Id: Ia33a9ae4d8134b5ad0c8b7cf6812fbdd625ca89e
    Reviewed-on: https://gerrit.libreoffice.org/c/core/+/106577
    Tested-by: Jenkins
    Reviewed-by: Stephan Bergmann <sbergman at redhat.com>

diff --git a/include/o3tl/safeint.hxx b/include/o3tl/safeint.hxx
index 6d8d1304fdf3..a5c212244c7c 100644
--- a/include/o3tl/safeint.hxx
+++ b/include/o3tl/safeint.hxx
@@ -234,6 +234,11 @@ make_unsigned(T value)
     return value;
 }
 
+// An implicit conversion from T2 to T1, useful in places where an explicit conversion from T2 to
+// T1 is needed (e.g., in list initialization, if the implicit conversion would be narrowing) but
+// tools like -fsanitize=implict-conversion should still be able to detect truncation:
+template<typename T1, typename T2> constexpr T1 narrowing(T2 value) { return value; }
+
 }
 
 #endif
diff --git a/vcl/win/gdi/DWriteTextRenderer.cxx b/vcl/win/gdi/DWriteTextRenderer.cxx
index da8eab0e6ce0..185925ae7967 100644
--- a/vcl/win/gdi/DWriteTextRenderer.cxx
+++ b/vcl/win/gdi/DWriteTextRenderer.cxx
@@ -30,6 +30,7 @@
 #include <winver.h>
 
 #include <comphelper/windowserrorstring.hxx>
+#include <o3tl/safeint.hxx>
 #include <sal/log.hxx>
 
 namespace
@@ -190,7 +191,9 @@ bool D2DWriteTextOutRenderer::Ready() const
 
 HRESULT D2DWriteTextOutRenderer::BindDC(HDC hDC, tools::Rectangle const & rRect)
 {
-    RECT const rc = { rRect.Left(), rRect.Top(), rRect.Right(), rRect.Bottom() };
+    RECT const rc = {
+        o3tl::narrowing<LONG>(rRect.Left()), o3tl::narrowing<LONG>(rRect.Top()),
+        o3tl::narrowing<LONG>(rRect.Right()), o3tl::narrowing<LONG>(rRect.Bottom()) };
     return CHECKHR(mpRT->BindDC(hDC, &rc));
 }
 
diff --git a/vcl/win/gdi/winlayout.cxx b/vcl/win/gdi/winlayout.cxx
index 7863a3c353d2..398196438fb7 100644
--- a/vcl/win/gdi/winlayout.cxx
+++ b/vcl/win/gdi/winlayout.cxx
@@ -21,6 +21,8 @@
 #include <config_features.h>
 
 #include <memory>
+
+#include <o3tl/safeint.hxx>
 #include <osl/module.h>
 #include <osl/file.h>
 #include <sal/log.hxx>
@@ -594,8 +596,9 @@ void WinSalGraphics::DrawTextLayout(const GenericSalLayout& rLayout)
         // we are making changes to the DC, make sure we got a new one
         assert(aDC->getCompatibleHDC() != hDC);
 
-        RECT aWinRect = { aRect.Left(), aRect.Top(), aRect.Left() + aRect.GetWidth(),
-                          aRect.Top() + aRect.GetHeight() };
+        RECT aWinRect = { o3tl::narrowing<LONG>(aRect.Left()), o3tl::narrowing<LONG>(aRect.Top()),
+                          o3tl::narrowing<LONG>(aRect.Left() + aRect.GetWidth()),
+                          o3tl::narrowing<LONG>(aRect.Top() + aRect.GetHeight()) };
         ::FillRect(aDC->getCompatibleHDC(), &aWinRect,
                    static_cast<HBRUSH>(::GetStockObject(WHITE_BRUSH)));