add string_view variants of methods to O[U]StringBuffer

and update the stringview loplugin to detect cases where we can
use these new methods.

Change-Id: I998efe02e35c8efcb3abfb4d7186165bbe6dfb2c
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/110046
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

2 files changed, 92 insertions, 3 deletions

diff --git a/compilerplugins/clang/stringview.cxx b/compilerplugins/clang/stringview.cxx
index abfc87f78fd6..5df91dcad054 100644
--- a/compilerplugins/clang/stringview.cxx
+++ b/compilerplugins/clang/stringview.cxx
@@ -51,8 +51,11 @@ public:
     bool VisitFunctionDecl(FunctionDecl const*);
     bool VisitCXXOperatorCallExpr(CXXOperatorCallExpr const*);
     bool VisitImplicitCastExpr(ImplicitCastExpr const*);
+    bool VisitCXXMemberCallExpr(CXXMemberCallExpr const*);
+    bool VisitCXXConstructExpr(CXXConstructExpr const*);
 
 private:
+    void handleSubExprThatCouldBeView(Expr const* expr);
     void handleCXXConstructExpr(CXXConstructExpr const* expr);
     void handleCXXMemberCallExpr(CXXMemberCallExpr const* expr);
 };
@@ -88,6 +91,20 @@ bool StringView::VisitCXXOperatorCallExpr(CXXOperatorCallExpr const* cxxOperator
         check(cxxOperatorCallExpr->getArg(1));
     else if (op == OO_Subscript)
         check(cxxOperatorCallExpr->getArg(0));
+    else if (op == OO_Equal)
+    {
+        if (loplugin::TypeCheck(cxxOperatorCallExpr->getType())
+                .Class("OUStringBuffer")
+                .Namespace("rtl")
+                .GlobalNamespace()
+            || loplugin::TypeCheck(cxxOperatorCallExpr->getType())
+                   .Class("OStringBuffer")
+                   .Namespace("rtl")
+                   .GlobalNamespace())
+        {
+            check(cxxOperatorCallExpr->getArg(1));
+        }
+    }
     return true;
 }
 
@@ -111,12 +128,18 @@ bool StringView::VisitImplicitCastExpr(ImplicitCastExpr const* expr)
     {
         return true;
     }
-    auto const e = expr->getSubExprAsWritten()->IgnoreParens();
+    handleSubExprThatCouldBeView(expr->getSubExprAsWritten());
+    return true;
+}
+
+void StringView::handleSubExprThatCouldBeView(Expr const* subExpr)
+{
+    auto const e = subExpr->IgnoreParens();
     auto const tc = loplugin::TypeCheck(e->getType());
     if (!(tc.Class("OString").Namespace("rtl").GlobalNamespace()
           || tc.Class("OUString").Namespace("rtl").GlobalNamespace()))
     {
-        return true;
+        return;
     }
     if (auto const e1 = dyn_cast<CXXConstructExpr>(e))
     {
@@ -138,7 +161,6 @@ bool StringView::VisitImplicitCastExpr(ImplicitCastExpr const* expr)
     {
         handleCXXMemberCallExpr(e3);
     }
-    return true;
 }
 
 void StringView::handleCXXConstructExpr(CXXConstructExpr const* expr)
@@ -229,6 +251,61 @@ void StringView::handleCXXMemberCallExpr(CXXMemberCallExpr const* expr)
         << expr->getSourceRange();
 }
 
+/** check for calls to O[U]StringBuffer::append that could be passed as a
+    std::u16string_view */
+bool StringView::VisitCXXMemberCallExpr(CXXMemberCallExpr const* expr)
+{
+    if (ignoreLocation(expr))
+    {
+        return true;
+    }
+    if (!loplugin::TypeCheck(expr->getType())
+             .Class("OUStringBuffer")
+             .Namespace("rtl")
+             .GlobalNamespace()
+        && !loplugin::TypeCheck(expr->getType())
+                .Class("OStringBuffer")
+                .Namespace("rtl")
+                .GlobalNamespace())
+    {
+        return true;
+    }
+    auto const dc = loplugin::DeclCheck(expr->getMethodDecl());
+    if (dc.Function("append") || dc.Function("indexOf") || dc.Function("lastIndexOf"))
+    {
+        handleSubExprThatCouldBeView(compat::IgnoreImplicit(expr->getArg(0)));
+    }
+    else if (dc.Function("insert"))
+    {
+        handleSubExprThatCouldBeView(compat::IgnoreImplicit(expr->getArg(1)));
+    }
+    return true;
+}
+
+/** check for calls to O[U]StringBuffer constructor that could be passed as a
+    std::u16string_view */
+bool StringView::VisitCXXConstructExpr(CXXConstructExpr const* expr)
+{
+    if (ignoreLocation(expr))
+    {
+        return true;
+    }
+    if (!loplugin::TypeCheck(expr->getType())
+             .Class("OUStringBuffer")
+             .Namespace("rtl")
+             .GlobalNamespace()
+        && !loplugin::TypeCheck(expr->getType())
+                .Class("OStringBuffer")
+                .Namespace("rtl")
+                .GlobalNamespace())
+    {
+        return true;
+    }
+    if (expr->getNumArgs() > 0)
+        handleSubExprThatCouldBeView(compat::IgnoreImplicit(expr->getArg(0)));
+    return true;
+}
+
 loplugin::Plugin::Registration<StringView> stringview("stringview");
 }
 
diff --git a/compilerplugins/clang/test/stringview.cxx b/compilerplugins/clang/test/stringview.cxx
index d40ee50175a1..142bba799008 100644
--- a/compilerplugins/clang/test/stringview.cxx
+++ b/compilerplugins/clang/test/stringview.cxx
@@ -140,4 +140,16 @@ void f5(char const* s1, sal_Int32 n1, char16_t const* s2, sal_Int32 n2)
     call_view(OUString(OUString::number(0)));
 }
 
+void f5(OUString s)
+{
+    // expected-error@+1 {{rather than copy, pass with a view using subView() [loplugin:stringview]}}
+    OUStringBuffer buf(s.copy(5));
+    // expected-error@+1 {{rather than copy, pass with a view using subView() [loplugin:stringview]}}
+    buf = s.copy(5);
+    // expected-error@+1 {{rather than copy, pass with a view using subView() [loplugin:stringview]}}
+    buf.append(s.copy(12));
+    // expected-error@+1 {{instead of an 'rtl::OUString', pass a 'std::u16string_view' [loplugin:stringview]}}
+    buf.append(OUString(std::u16string_view(u"foo")));
+}
+
 /* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */