Silence -Werror,-Wunused-variable (clang-cl)

Required a workaround for loplugin:indentation, until
<https://reviews.llvm.org/D68581> "Include leading attributes in DeclStmt's
SourceRange" lands in Clang.

Change-Id: I7192969d40fa4c50bbd603d059532b9344865248
Reviewed-on: https://gerrit.libreoffice.org/80596
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/compilerplugins/clang/indentation.cxx b/compilerplugins/clang/indentation.cxx
index eaa795e6765a..57fbd1b382a0 100644
--- a/compilerplugins/clang/indentation.cxx
+++ b/compilerplugins/clang/indentation.cxx
@@ -120,6 +120,22 @@ bool Indentation::VisitCompoundStmt(CompoundStmt const* compoundStmt)
         // these are always weirdly indented
         if (isa<LabelStmt>(stmt))
             continue;
+        // At least until Clang 9.0.0, getBeginLoc of a VarDecl DeclStmt with an UnusedAttr points
+        // after the attr (and getLocation of the attr would point at "maybe_unused", not at the
+        // leading "[["), so just ignore those at least for now:
+        if (auto const declStmt = dyn_cast<DeclStmt>(stmt))
+        {
+            if (declStmt->decl_begin() != declStmt->decl_end())
+            {
+                if (auto const decl = dyn_cast<VarDecl>(*declStmt->decl_begin()))
+                {
+                    if (decl->hasAttr<UnusedAttr>())
+                    {
+                        continue;
+                    }
+                }
+            }
+        }
 
         auto stmtLoc = compat::getBeginLoc(stmt);