At block scope, an identifier followed by a single colon introduces a label. Thus, your statement is equivalent to:

    set&lt;string&gt; keys;

except that it bears the label `std` and can be jumped to by the statement `goto std;`.

For some reason, the name `set` is known to the compiler---perhaps you did `using namespace std;`, or `using std::set;`, or something like that, or perhaps you defined your own `set` type somewhere.

In the second case, std is a label.  It is the same as spelling default incorrectly in a case statement.

I have submitted a Single View Swift iOS application to App Store Connect. The application is not Document Based.

The application uploads successfully, but I get the following warning in an email from Apple. I can still test the application through Test Flight, but I want to eliminate the warning.

&quot;Invalid Document Configuration - Document Based Apps should support either the Document Browser (UISupportsDocumentBrowser = YES) or implement Open In Place (LSSupportsOpeningDocumentsInPlace = YES/NO).&quot;


App Store Connect Warns - Invalid Document Configuration

I have created sign up screen in the flutter. I want to get the email and password in the `onPressed` of the `FlatButton`.

Does anyone know how to do this in flutter ? 

      Widget SignupPage() {
        return new Scaffold(body: Container(
          height: MediaQuery.of(context).size.height,
          decoration: BoxDecoration(
            color: Colors.white,
            image: DecorationImage(
              colorFilter: new ColorFilter.mode(
                  Colors.black.withOpacity(0.05), BlendMode.dstATop),
              image: AssetImage(&#39;assets/images/mountains.jpg&#39;),
              fit: BoxFit.cover,
            ),
          ),
          child: new Column(
            children: &lt;Widget&gt;[
              Container(
                padding: EdgeInsets.all(100.0),
                child: Center(
                  child: Icon(
                    Icons.headset_mic,
                    color: Colors.redAccent,
                    size: 50.0,
                  ),
                ),
              ),
              new Row(
                children: &lt;Widget&gt;[
                  new Expanded(
                    child: new Padding(
                      padding: const EdgeInsets.only(left: 40.0),
                      child: new Text(
                        &quot;EMAIL&quot;,
                        style: TextStyle(
                          fontWeight: FontWeight.bold,
                          color: Colors.redAccent,
                          fontSize: 15.0,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
              new Container(
                width: MediaQuery.of(context).size.width,
                margin: const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
                alignment: Alignment.center,
                decoration: BoxDecoration(
                  border: Border(
                    bottom: BorderSide(
                        color: Colors.redAccent,
                        width: 0.5,
                        style: BorderStyle.solid),
                  ),
                ),
                padding: const EdgeInsets.only(left: 0.0, right: 10.0),
                child: new Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: &lt;Widget&gt;[
                    new Expanded(
                      child: TextField(
                        obscureText: true,
                        textAlign: TextAlign.left,
                        decoration: InputDecoration(
                          border: InputBorder.none,
                          hintText: &#39;PLEASE ENTER YOUR EMAIL&#39;,
                          hintStyle: TextStyle(color: Colors.grey),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              Divider(
                height: 24.0,
              ),
              new Row(
                children: &lt;Widget&gt;[
                  new Expanded(
                    child: new Padding(
                      padding: const EdgeInsets.only(left: 40.0),
                      child: new Text(
                        &quot;PASSWORD&quot;,
                        style: TextStyle(
                          fontWeight: FontWeight.bold,
                          color: Colors.redAccent,
                          fontSize: 15.0,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
              new Container(
                width: MediaQuery.of(context).size.width,
                margin: const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
                alignment: Alignment.center,
                decoration: BoxDecoration(
                  border: Border(
                    bottom: BorderSide(
                        color: Colors.redAccent,
                        width: 0.5,
                        style: BorderStyle.solid),
                  ),
                ),
                padding: const EdgeInsets.only(left: 0.0, right: 10.0),
                child: new Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: &lt;Widget&gt;[
                    new Expanded(
                      child: TextField(
                        obscureText: true,
                        textAlign: TextAlign.left,
                        decoration: InputDecoration(
                          border: InputBorder.none,
                          hintText: &#39;*********&#39;,
                          hintStyle: TextStyle(color: Colors.grey),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              Divider(
                height: 24.0,
              ),
              new Row(
                children: &lt;Widget&gt;[
                  new Expanded(
                    child: new Padding(
                      padding: const EdgeInsets.only(left: 40.0),
                      child: new Text(
                        &quot;CONFIRM PASSWORD&quot;,
                        style: TextStyle(
                          fontWeight: FontWeight.bold,
                          color: Colors.redAccent,
                          fontSize: 15.0,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
              new Container(
                width: MediaQuery.of(context).size.width,
                margin: const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
                alignment: Alignment.center,
                decoration: BoxDecoration(
                  border: Border(
                    bottom: BorderSide(
                        color: Colors.redAccent,
                        width: 0.5,
                        style: BorderStyle.solid),
                  ),
                ),
                padding: const EdgeInsets.only(left: 0.0, right: 10.0),
                child: new Row(
                  crossAxisAlignment: CrossAxisAlignment.center,
                  mainAxisAlignment: MainAxisAlignment.start,
                  children: &lt;Widget&gt;[
                    new Expanded(
                      child: TextField(
                        obscureText: true,
                        textAlign: TextAlign.left,
                        decoration: InputDecoration(
                          border: InputBorder.none,
                          hintText: &#39;*********&#39;,
                          hintStyle: TextStyle(color: Colors.grey),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
              Divider(
                height: 24.0,
              ),
              new Row(
                mainAxisAlignment: MainAxisAlignment.end,
                children: &lt;Widget&gt;[
                  Padding(
                    padding: const EdgeInsets.only(right: 20.0),
                    child: new FlatButton(
                      child: new Text(
                        &quot;Already have an account?&quot;,
                        style: TextStyle(
                          fontWeight: FontWeight.bold,
                          color: Colors.redAccent,
                          fontSize: 15.0,
                        ),
                        textAlign: TextAlign.end,
                      ),
                      onPressed: () =&gt; {},
                    ),
                  ),
                ],
              ),
              new Container(
                width: MediaQuery.of(context).size.width,
                margin: const EdgeInsets.only(left: 30.0, right: 30.0, top: 50.0),
                alignment: Alignment.center,
                child: new Row(
                  children: &lt;Widget&gt;[
                    new Expanded(
                      child: new FlatButton(
                        shape: new RoundedRectangleBorder(
                          borderRadius: new BorderRadius.circular(30.0),
                        ),
                        color: Colors.redAccent,
                        onPressed: () =&gt; authHandler.handleSignInEmail(emailController.text, passwordController.text)
                            .then((FirebaseUser user) {
                          Navigator.push(context, new MaterialPageRoute(builder: (context) =&gt; HomePage()));
                        }).catchError((e) =&gt; print(e)),
                        child: new Container(
                          padding: const EdgeInsets.symmetric(
                            vertical: 20.0,
                            horizontal: 20.0,
                          ),
                          child: new Row(
                            mainAxisAlignment: MainAxisAlignment.center,
                            children: &lt;Widget&gt;[
                              new Expanded(
                                child: Text(
                                  &quot;SIGN UP&quot;,
                                  textAlign: TextAlign.center,
                                  style: TextStyle(
                                      color: Colors.white,
                                      fontWeight: FontWeight.bold),
                                ),
                              ),
                            ],
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            ],
          ),
        ));
      }



How to get the TextField value in flutter

I accidentally wrote 

    std::set&lt;string&gt; keys;

as:

    std:set&lt;string&gt; keys;

but weirdly enough, Visual Studio 2013 still compiles. 

Why does this happen? 

Actually `keys` is not only defined, but later used as a set of strings, such as

    if(keys.find(keystr)==keys.end()){
    	keys.insert(keystr);
    	toret.push_back(tempv);
    }

Why can std:set (with a single colon) compile?

I accidentally wrote
<pre><code class="hljs language-c">std::set&#x3C;string> keys;
</code></pre>
as:
<pre><code class="hljs language-c">std:set&#x3C;string> keys;
</code></pre>
but weirdly enough, Visual Studio 2013 still compiles.
Why does this happen?
Actually <code>keys</code> is not only defined, but later used as a set of strings, such as
<pre><code class="hljs language-scss">if(keys.find(keystr)==keys.end()){
	keys.insert(keystr);
	toret.push_back(tempv);
}
</code></pre>

I&#39;m investigating ways to speed up a large section of C++ code, which has automatic derivatives for computing jacobians. This involves doing some amount of work in the actual residuals, but the majority of the work (based on profiled execution time) is in calculating the jacobians. 

This surprised me, since most of the jacobians are propagated forward from 0s and 1s, so the amount of work should be 2-4x the function, not 10-12x. In order to model what a large amount of the jacobian work is like, I made a super minimal example with just a dot product (instead of sin, cos, sqrt and more that would be in a real situation) that the compiler should be able to optimize to a single return value:

    #include &lt;Eigen/Core&gt;
    #include &lt;Eigen/Geometry&gt;

    using Array12d = Eigen::Matrix&lt;double,12,1&gt;;

    double testReturnFirstDot(const Array12d&amp; b)
    {
        Array12d a;
        a.array() = 0.;
        a(0) = 1.;
	    return a.dot(b);
    }

Which should be the same as 

    double testReturnFirst(const Array12d&amp; b)
    {
        return b(0);
    }

I was disappointed to find that, without fast-math enabled, neither GCC 8.2, Clang 6 or MSVC 19 were able to make any optimizations at all over the naive dot-product with a matrix full of 0s. Even with fast-math (https://godbolt.org/z/GvPXFy) the optimizations are very poor in GCC and Clang (still involve multiplications and additions), and MSVC doesn&#39;t do any optimizations at all.

I don&#39;t have a background in compilers, but is there a reason for this? I&#39;m fairly sure that in a large proportion of scientific computations being able to do better constant propagation/folding would make more optimizations apparent, even if the constant-fold itself didn&#39;t result in a speedup.

While I&#39;m interested in explanations for why this isn&#39;t done on the compiler side, I&#39;m also interested for what I can do on a practical side to make my own code faster when facing these kinds of patterns.

Why don&#39;t C++ compilers do better constant folding?

I saw [this example in cppreference&#39;s documentation for `std::numeric_limits`][1]

    #include &lt;limits&gt;
    #include &lt;iostream&gt;
     
    int main() 
    {
        std::cout &lt;&lt; &quot;type\tlowest()\tmin()\t\tmax()\n\n&quot;;
     
        std::cout &lt;&lt; &quot;uchar\t&quot;
                  &lt;&lt; +std::numeric_limits&lt;unsigned char&gt;::lowest() &lt;&lt; &#39;\t&#39; &lt;&lt; &#39;\t&#39;
                  &lt;&lt; +std::numeric_limits&lt;unsigned char&gt;::min() &lt;&lt; &#39;\t&#39; &lt;&lt; &#39;\t&#39;
                  &lt;&lt; +std::numeric_limits&lt;unsigned char&gt;::max() &lt;&lt; &#39;\n&#39;;
        std::cout &lt;&lt; &quot;int\t&quot;
                  &lt;&lt; std::numeric_limits&lt;int&gt;::lowest() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;int&gt;::min() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;int&gt;::max() &lt;&lt; &#39;\n&#39;;
        std::cout &lt;&lt; &quot;float\t&quot;
                  &lt;&lt; std::numeric_limits&lt;float&gt;::lowest() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;float&gt;::min() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;float&gt;::max() &lt;&lt; &#39;\n&#39;;
        std::cout &lt;&lt; &quot;double\t&quot;
                  &lt;&lt; std::numeric_limits&lt;double&gt;::lowest() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;double&gt;::min() &lt;&lt; &#39;\t&#39;
                  &lt;&lt; std::numeric_limits&lt;double&gt;::max() &lt;&lt; &#39;\n&#39;;
    }

I don&#39;t understand the &quot;+&quot; operator in 

    &lt;&lt; +std::numeric_limits&lt;unsigned char&gt;::lowest()
I have tested it, replaced it with &quot;-&quot;, and that also worked.
What is the use of such a &quot;+&quot; operator?

  [1]: https://en.cppreference.com/w/cpp/types/numeric_limits

What is the purpose of a unary &quot;+&quot; before a call to std::numeric_limits&lt;unsigned char&gt; members?

Consider this fairly useless program:

    #include &lt;iostream&gt;
    int main(int argc, char* argv[]) {
    
      int a = 5;
    
      auto it = [&amp;](auto self) {
          return [&amp;](auto b) {
            std::cout &lt;&lt; (a + b) &lt;&lt; std::endl;
            return self(self);
          };
      };
      it(it)(4)(6)(42)(77)(999);
    }

Basically we are trying to make a lambda that returns itself. 

- MSVC compiles the program, and it runs
- gcc compiles the program, and it segfaults
- clang rejects the program with a message:
&gt;`error: function &#39;operator()&lt;(lambda at lam.cpp:6:13)&gt;&#39; with deduced return type cannot be used before it is defined`

Which compiler is right? Is there a static constraint violation, UB, or neither?

**Update** this slight modification is accepted by clang:

      auto it = [&amp;](auto&amp; self, auto b) {
              std::cout &lt;&lt; (a + b) &lt;&lt; std::endl;
              return [&amp;](auto p) { return self(self,p); };
      };
      it(it,4)(6)(42)(77)(999);

**Update 2**: I understand how to write a functor that returns itself, or how to use the Y combinator, to achieve this. This is more a language-lawyer question.

**Update 3**: the question is *not* whether it is legal for a lambda to return itself in general, but about the legality of this specific way of doing this. 

Related question: [C++ lambda returning itself](https://stackoverflow.com/questions/52173762/c-lambda-returning-itself).


Lambda returning itself: is this legal?

Inspired by [this answer](https://stackoverflow.com/a/52355930/7151494), I tried to copy and paste (and add testing in `main()`) this code:

    template&lt;typename T&gt;
    std::tuple&lt;int, double&gt; foo(T a) {
        if constexpr (std::is_same_v&lt;int, T&gt;)
            return {a, 0.0};
        else if (std::is_same_v&lt;double, T&gt;)
            return {0, a};
        else
            return {0, 0.0};
    }
    
    int main() {
        auto [x, y] = foo(&quot;&quot;);
        std::cout &lt;&lt; x &lt;&lt; &quot; &quot; &lt;&lt; y;
    }
This is very straightforward - if `T` is deduced as `int`, we want to return a tuple of `[a, 0.0]`. If `T` is deduced as `double`, we want to return a tuple of  `[0, a]`. Otherwise, we want to return `[0, 0.0]`.

As you can see, in the `main()` function, I am calling `foo` with `const char*` argument, which *should* result in `x` and `y` being `0`. That is *not the case*.

While trying to compile it, I encountered a strange error:

&gt; error: could not convert &#39;`{0, a}`&#39; from &#39;`&lt;brace-enclosed initializer list&gt;`&#39; to &#39;`std::tuple&lt;int, double&gt;`&#39;

And I was like *what?*. Why on earth would I want that... I specifically used `std::is_same` to enable `return {0, a}` **only** when the type of `a` is deduced as `double`.

So I quickly ran to [cppreference](https://en.cppreference.com/w/cpp/language/if) on if-constexpr. At the bottom of the page, above **Notes**, we can see this snippet of code: 

    extern int x; // no definition of x required
    int f() {
    if constexpr (true)
        return 0;
    else if (x)
        return x;
    else
        return -x;
    }

I thought to myself *oookay..? I can&#39;t really see what&#39;s wrong with the original code. They use the same syntax and semantics...*.

But I was curious. I was curious if maybe something odd (at that time) might fix that issue, so I changed the original code to:

    template&lt;typename T&gt;
    std::tuple&lt;int, double&gt; foo(T a) {
        if constexpr (std::is_same_v&lt;int, T&gt;)
            return {a, 0.0};
        else if constexpr (std::is_same_v&lt;double, T&gt;) // notice the additional constexpr here
            return {0, a};
        else
            return {0, 0.0};
    }
    
    int main() {
        auto [x, y] = foo(&quot;&quot;);
        std::cout &lt;&lt; x &lt;&lt; &quot; &quot; &lt;&lt; y;
    }

And voil&#224;! The code compiled and executed as expected. So, my question is - **Do we need to put `constexpr` after every `if` statement in `if-else` statement in these kind of situations?** Or is it just my compiler? I am using GCC 7.3.

Do I need to put constexpr after else-if?

NOTE: This is a [tag:C] question, though I added [tag:C++] in case some C++ expert can provide a rationale or historical reason why C++ is using a different wording than C.

---

In the C standard library specification, we have this normative text, C17 7.1.3 Reserved identifiers (emphasis mine):

&gt; -  All identifiers that begin with an underscore and either an uppercase letter or another underscore **are always reserved for any use**.
- All identifiers that begin with an underscore are always reserved for use as identifiers with file scope in both the ordinary and tag name spaces.

Now I keep reading answers on SO by various esteemed C experts, where they claim it is fine for a compiler or standard library to use identifiers with underscore + uppercase, or double underscore.

Doesn&#39;t &quot;reserved for any use&quot; mean reserved for _anyone_ except future extensions to the C language itself? Meaning that the implementation is _not_ allowed to use them. 

While the second phrase above, regarding single leading underscore seems to be directed to the implementation?

In general, the C standard is written in a way that expects compiler vendors/library implementers to be the typical reader - not so much the application programmers.


Notably, C++ has a very different wording:

&gt; - Each name that contains a double underscore (`__`) or begins with an underscore followed by an uppercase letter (2.11) **is reserved to the implementation for any use**.

(See https://stackoverflow.com/questions/228783/what-are-the-rules-about-using-an-underscore-in-a-c-identifier) 

Is this perhaps a mix-up between C and C++ and the languages are different here?

What&#39;s the meaning of &quot;reserved for any use&quot;?

I&#39;m attempting to build my first F# Android project in Visual Studio 2017 *(Community Edition)*.

Immediately after creating a new project by using the F# - Android - Blank App template, the error window in Visual Studio displays the following message:

&gt; The project Foo is missing Android SDKs required for building. Double-click on this message and follow the prompts to install them.

No amount of double-clicking on the message causes prompts to appear.

I can&#39;t find an obvious place to download the Android SDK from:

The SDK manager that I remember from a while ago seems to have disappeared from the Android developer website.

I&#39;ve installed Android Studio, which seemed to download some Android SDKs, but Visual Studio still can&#39;t seem to find whatever it&#39;s looking for.

The project is missing Android SDKs required for building

I have 2 projects in my solution, I have a project with Entity Framework Core installed:

[![enter image description here][1]][1]

And in the other ASP.NET Web API project I have these packages:

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot;?&gt;
    &lt;packages&gt;
      &lt;package id=&quot;Antlr&quot; version=&quot;3.5.0.2&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.Agent.Intercept&quot; version=&quot;2.4.0&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.DependencyCollector&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.PerfCounterCollector&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.Web&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.WindowsServer&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.ApplicationInsights.WindowsServer.TelemetryChannel&quot; version=&quot;2.5.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.Mvc&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.Razor&quot; version=&quot;3.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.TelemetryCorrelation&quot; version=&quot;1.0.0&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.Web.Optimization&quot; version=&quot;1.1.3&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebApi&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebApi.Client&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebApi.Core&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebApi.HelpPage&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebApi.WebHost&quot; version=&quot;5.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.AspNet.WebPages&quot; version=&quot;3.2.4&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.CodeDom.Providers.DotNetCompilerPlatform&quot; version=&quot;2.0.0&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Microsoft.Web.Infrastructure&quot; version=&quot;1.0.0.0&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;Newtonsoft.Json&quot; version=&quot;11.0.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;System.Diagnostics.DiagnosticSource&quot; version=&quot;4.4.1&quot; targetFramework=&quot;net461&quot; /&gt;
      &lt;package id=&quot;WebGrease&quot; version=&quot;1.6.0&quot; targetFramework=&quot;net461&quot; /&gt;
    &lt;/packages&gt;

When I run `Add-Migration` in PMC:

&gt; Your startup project &#39;API&#39; doesn&#39;t reference
&gt; Microsoft.EntityFrameworkCore.Design. This package is required for the
&gt; Entity Framework Core Tools to work. Ensure your startup project is
&gt; correct, install the package, and try again.

I installed Microsoft.EntityFrameworkCore.Design in the startup project instead of the data project that will contain all the entities and now it works, is this how the project should be setup?

  [1]: https://i.stack.imgur.com/p3cQA.png

Your startup project doesn&#39;t reference Microsoft.EntityFrameworkCore.Design

Previously, I was able to select the .NET Core 2.2 Framework in the properties section of the .NET Core project, but after the latest visual studio updates I haven&#39;t been able to. 


[![Framework Selection][1]][1]

Things I&#39;ve tried:

 - Repairing the .NET Core 2.2 SDK installation
 - Uninstalling and Reinstalling the .NET Core 2.2 SDK
 - Restarting Visual Studio
 - Restarting my machine
 - Making a fresh .NET Core project

Nothing has been able to work. From the fact that it was working before I installed the latest updates, could it just be a bug? Or is there something that I&#39;m missing? 

For some more clarity, I&#39;m running in Windows 10 Professional x64 on the latest version of windows. 

I installed this version of .NET Core 2.2 [from here][2] 

[![enter image description here][3]][3]

Any help is appreciated. Thanks!


  [1]: https://i.stack.imgur.com/qKU8w.png
  [2]: https://www.microsoft.com/net/download/dotnet-core/2.2
  [3]: https://i.stack.imgur.com/TIhxO.png

.NET Core 2.2 Can&#39;t be Selected In Visual Studio Build Framework

According to the [C# 8 announcement video][1] the &quot;nullable reference types&quot; feature can be enabled for the whole project.

But how to enable it for the project? I did not find any new appropriate option in the Project Properties window in Visual Studio 2019 Preview 1.

Can it be enabled for &#39;legacy&#39; `.csproj` projects if the C# language version is changed to 8.0?

  [1]: https://youtu.be/VdC0aoa7ung?t=137

How to enable Nullable Reference Types feature of C# 8.0 for the whole project

I can&#39;t use `*` in assembly version; when I do I get the following compilation error:

&gt; The specified version string contains wildcards, which are not
&gt; compatible with determinism. Either remove wildcards from the version
&gt; string, or disable determinism for this compilation

![SCRAssembly][1]


  [1]: https://i.stack.imgur.com/uE5af.png

Content Type	Original Author	Original Content on Stackoverflow
Question	athos	View Question on Stackoverflow
Solution 1 - C++	Brian Bi	View Answer on Stackoverflow
Solution 2 - C++	cup	View Answer on Stackoverflow

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