fix o3tl::equalsIgnoreAsciiCase()

As the OUString equivalent shows, it needs to check == 0. Commit
33ecd0d5c4 for some reason also
dropped the cheap checks (even from OUString) that OString has,
so add them.

Change-Id: I88e68b5ae10fd76c3c08b9b36d5abed0fad17bbf
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/130753
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>
Tested-by: Jenkins

include/o3tl/string_view.hxx

@@ -23,7 +23,12 @@ namespace o3tl
 // Like OUString::equalsIgnoreAsciiCase, but for two std::u16string_view:
 inline bool equalsIgnoreAsciiCase(std::u16string_view s1, std::u16string_view s2)
 {
-    return rtl_ustr_compareIgnoreAsciiCase_WithLength(s1.data(), s1.size(), s2.data(), s2.size());
+    if (s1.size() != s2.size())
+        return false;
+    if (s1.data() == s2.data())
+        return true;
+    return rtl_ustr_compareIgnoreAsciiCase_WithLength(s1.data(), s1.size(), s2.data(), s2.size())
+           == 0;
 };
 
 // Similar to OString::getToken, returning the first token of a std::string_view, starting at a

include/rtl/ustring.hxx

@@ -977,6 +977,10 @@ public:
     */
 #if defined LIBO_INTERNAL_ONLY
     bool equalsIgnoreAsciiCase(std::u16string_view sv) const {
+        if ( sal_uInt32(pData->length) != sv.size() )
+            return false;
+        if ( pData->buffer == sv.data() )
+            return true;
         return
             rtl_ustr_compareIgnoreAsciiCase_WithLength(
                 pData->buffer, pData->length, sv.data(), sv.size())

o3tl/qa/test-string_view.cxx

@@ -60,6 +60,7 @@ private:
     CPPUNIT_TEST(testStartsWithRest);
     CPPUNIT_TEST(testEndsWith);
     CPPUNIT_TEST(testEndsWithRest);
+    CPPUNIT_TEST(testEqualsIgnoreAsciiCase);
     CPPUNIT_TEST_SUITE_END();
 
     void testStartsWith()
@@ -585,6 +586,13 @@ private:
             CPPUNIT_ASSERT_EQUAL(u""sv, rest);
         }
     }
+
+    void testEqualsIgnoreAsciiCase()
+    {
+        using namespace std::string_view_literals;
+        CPPUNIT_ASSERT(o3tl::equalsIgnoreAsciiCase(u"test"sv, u"test"sv));
+        CPPUNIT_ASSERT(!o3tl::equalsIgnoreAsciiCase(u"test"sv, u"test2"sv));
+    }
 };
 
 CPPUNIT_TEST_SUITE_REGISTRATION(Test);