new loplugin writeonlyvars

largely based on the relevant portion of the unusedfields loplugin, but
adapted for local vars

Change-Id: Ic522a941573940e8f75c88f90ba5f37508ca49b1
Reviewed-on: https://gerrit.libreoffice.org/66835
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

compilerplugins/clang/test/writeonlyvars.cxx

@@ -0,0 +1,147 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4; fill-column: 100 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <vector>
+#include <ostream>
+#include <com/sun/star/uno/Any.hxx>
+#include <com/sun/star/uno/Sequence.hxx>
+
+namespace Bar
+{
+void test()
+{
+    // check that we DON'T see reads here
+    // expected-error@+1 {{write m_bar3 [loplugin:writeonlyvars]}}
+    int* m_bar3;
+    // expected-error@+1 {{write m_bar3b [loplugin:writeonlyvars]}}
+    int* m_bar3b;
+    m_bar3 = nullptr;
+    m_bar3b = m_bar3 = nullptr;
+
+    // check that we see reads of field when passed to a function pointer
+    // check that we see read of a field that is a function pointer
+    // expected-error@+2 {{write m_bar4 [loplugin:writeonlyvars]}}
+    // expected-error@+1 {{read m_bar4 [loplugin:writeonlyvars]}}
+    int m_bar4;
+    // expected-error@+1 {{read m_barfunctionpointer [loplugin:writeonlyvars]}}
+    void (*m_barfunctionpointer)(int&) = nullptr;
+    m_barfunctionpointer(m_bar4);
+
+    // check that we see reads of a field when used in variable init
+    // expected-error@+1 {{read m_bar5 [loplugin:writeonlyvars]}}
+    int m_bar5 = 1;
+    int x = m_bar5;
+    (void)x;
+
+    // check that we see reads of a field when used in ranged-for
+    // expected-error@+1 {{read m_bar6 [loplugin:writeonlyvars]}}
+    std::vector<int> m_bar6;
+    for (auto i : m_bar6)
+    {
+        (void)i;
+    }
+
+    // check that we see writes of array fields
+    // expected-error@+1 {{write m_bar7 [loplugin:writeonlyvars]}}
+    int m_bar7[5];
+    m_bar7[3] = 1;
+
+    // check that we see reads when a field is used in an array expression
+    // expected-error@+1 {{read m_bar8 [loplugin:writeonlyvars]}}
+    int m_bar8 = 1;
+    // expected-error@+1 {{read tmp [loplugin:writeonlyvars]}}
+    char tmp[5];
+    auto x2 = tmp[m_bar8];
+    (void)x2;
+
+    // check that we don't see reads when calling operator>>=
+    // expected-error@+1 {{write m_bar9 [loplugin:writeonlyvars]}}
+    int m_bar9;
+    // expected-error@+1 {{read any [loplugin:writeonlyvars]}}
+    css::uno::Any any;
+    any >>= m_bar9;
+
+    // check that we see don't see writes when calling operator<<=
+    // expected-error@+1 {{read m_bar10 [loplugin:writeonlyvars]}}
+    int m_bar10;
+    // expected-error@+2 {{write any2 [loplugin:writeonlyvars]}}
+    // expected-error@+1 {{read any2 [loplugin:writeonlyvars]}}
+    css::uno::Any any2;
+    any2 <<= m_bar10;
+};
+};
+
+struct ReadOnly1
+{
+    ReadOnly1(int&);
+};
+
+namespace ReadOnlyAnalysis
+{
+void method1(int&);
+
+void test()
+{
+    // check that we see a write when we pass by non-const ref
+    // expected-error@+2 {{read m_f2 [loplugin:writeonlyvars]}}
+    // expected-error@+1 {{write m_f2 [loplugin:writeonlyvars]}}
+    int m_f2;
+    method1(m_f2);
+
+    // expected-error@+1 {{write m_f4 [loplugin:writeonlyvars]}}
+    std::vector<int> m_f4;
+    m_f4.push_back(1);
+
+    // check that we see a write when we pass by non-const ref
+    // expected-error@+2 {{read m_f5 [loplugin:writeonlyvars]}}
+    // expected-error@+1 {{write m_f5 [loplugin:writeonlyvars]}}
+    int m_f5;
+    ReadOnly1 a(m_f5);
+
+    // check that we see a write when we pass by non-const ref
+    // expected-error@+2 {{read m_f6 [loplugin:writeonlyvars]}}
+    // expected-error@+1 {{write m_f6 [loplugin:writeonlyvars]}}
+    int m_f6;
+    // expected-error@+1 {{write r [loplugin:writeonlyvars]}}
+    int& r = m_f6;
+    r = 1;
+};
+};
+
+void ReadOnlyAnalysis3()
+{
+    // expected-error@+1 {{read m_f1 [loplugin:writeonlyvars]}}
+    int m_f1 = 0;
+
+    if (m_f1)
+        m_f1 = 1;
+};
+
+// Verify the special logic for container fields that only contains mutations that
+// add elements.
+void ReadOnlyAnalysis4()
+{
+    // expected-error@+1 {{read m_readonly [loplugin:writeonlyvars]}}
+    std::vector<int> m_readonly;
+    // expected-error@+1 {{write m_writeonly [loplugin:writeonlyvars]}}
+    std::vector<int> m_writeonly;
+    // expected-error@+1 {{read m_readonlyCss [loplugin:writeonlyvars]}}
+    css::uno::Sequence<sal_Int32> m_readonlyCss;
+
+    // expected-error@+1 {{write x [loplugin:writeonlyvars]}}
+    int x = m_readonly[0];
+    (void)x;
+    *m_readonly.begin() = 1; // TODO?
+
+    m_writeonly.push_back(0);
+
+    x = m_readonlyCss.getArray()[0];
+};
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab cinoptions=b1,g0,N-s cinkeys+=0=break: */