After installing Visual Studio 2015 and building my project I receive the error
"CSC : error CS7038: Failed to emit module".
However my solution is building fine in Visual Studio 2013.
It is an ASP.NET webforms project .NET 4.0
Anyone?
UPDATE: it looks like the problem has to do with Red Gate Smart Assembly in combination with method parameters with default values.
UPDATE: Smart Assembly 6.9 fixes the error for me.
Original Snippet:
private void radButton1_Click(object sender, EventArgs e)
{
string perp = radTextBox1.Text;
int i = 0;
DataRow arp = ale.Rows[i];
while (i <= ale.Rows.Count)
{
if (ale.Rows[i].Field<>("FullName") = perp)
{
arp = ale.Rows[i];
ale.Rows.Remove(arp);
}
}
i = ale.Rows.Count;
radLabel1.Text = i.ToString();
}
Changed this:
if (ale.Rows[i].Field<>("FullName") = perp)
To This:
if (ale.Rows[i].Field<String>("FullName") == perp)
Got the same error (fresh installation of the VS2015 Enterprise, ASP.NET webforms project .NET 4.0).
After some investigation I've found that there are two DLLs in references which causes this. Both are .Net 2.0 assemblies and both of them obfuscated by Red Gate Smart Assembly 6.5. And the real reason is... obfuscation.
Luckily, these assemblies are mine, so I've tried to build them without using of Smart Assembly - error is gone.
Interesting is that no any errors or warnings shown by Visual Studio before trying to build a project.
Good luck!
EDIT: Updating Smart Assembly to version 6.9 fixed an issue.
As #Andrey reported this does appear to be an issue with obfuscated assemblies that is causing some difficulty for Roslyn. Today I was able to get a live repro of this error and the root cause appears to be the obfuscator is invalidating / corrupting how default parameter values are stored in metadata. When run through ildasm the default values will be displayed as:
.param [3] /* Invalid default value for 0800001F: */
The previous version of the compiler handled this scenario by treating the invalid value as null or default(T). We will be fixing Roslyn to have the same behavior.
I also had this exception being thrown in VB.NET (Visual Studio 2015 - Pro), and isolated a single line that was causing the error.
In the line of code below, if you define model as an integer, as in:
Dim model as Integer = 2
and then use:
Const N As Integer = model
you will throw the exception.
However, when I modified this to:
Dim N As Integer = model
the exception was not thrown. The Const syntax was legacy code from another program that I rapidly added model to, and constants can't be set to pre-defined integer types.
I just had "Failed to emit module". I mistakenly put empty brackets in a call to a generic extension method, only when inside a ternary operator, like this:
var a = b == 6 ? 8 : x.Foo<>();
(Outside of a ternary op, I just get regular error CS7003: Unexpected use of an unbound generic name.)
Extending on the answer from #jony-adamit:
I also had this compilation error being thrown in C# (Visual Studio 2015). It came down to the differences in compiler output from .NET 4.5 and Roslyn the new compiler in VS2015. You can take the below code and run it yourself or use dotnetfiddle (https://dotnetfiddle.net/fa2rMs) and switch between compilers.
In .NET 4.5 compiler (C# compiler version 12.0 or earlier) you get this message:
Compilation error (line 16, col 7): The type or namespace name
'Select' does not exist in the namespace 'Tools.Weapons' (are you
missing an assembly reference?)
In the Roslyn 1.0.0 and 1.1.0 compiler versions you get this message:
Compilation error (line 1, col 1): Failed to emit module
'MyAssembly'.
Code to reproduce the error (notice the namespace):
public class Program
{
public static void Main()
{
Tools.Delegater.Work();
}
}
namespace Tools
{
public static class Delegater
{
public static System.Action Work = () =>
{
var query = from x in Weapons
select x;
};
}
}
namespace Tools.Weapons
{
public class Cannon { }
}
As you can tell from the compiler messages, Roslyn's message leaves you guessing as to the what and the where about the compiler error. And depending on the size of the application, the lack of details could take days or weeks to discover the root cause. Whereas the message in the previous compiler pointed you to the exact spot to start reviewing your code.
Another big difference is the previous compiler will show you a syntax error in Visual Studio for this scenario, but unfortunately Roslyn (atm) does not. However, if you knew where to look and you hovered your mouse over the 'x' variable in the linq to sql statement, then you would see that Rosyln doesn't understand how to interpret it.
I was getting a similar error: "BC36970. Failed to emit module 'Something.dll'." I realize the error code is not the same but it is also a "failed to emit" type issue so I thought I'd share my answer.
Problem: My problem was that I had a string that was a constant but I was trying to append another string to it, like so (using VB code):
Dim MyString1 As String = "Test1"
Const MyString2 As String = "Test2" & MyString1
Solution: I simply had to convert the second string from Const to Dim and the error disappeared:
Dim MyString1 As String = "Test1"
Dim MyString2 As String = "Test2" & MyString1
I got this error when using a generic method but failing to include the type.
This code gave the error:
example.GetValue<>(foo);
Correction simply was to specify the type:
example.GetValue<string>(foo);
I'm not sure if the erroring example is valid syntax or not: I would have expected a syntax error if it is not rather than this error, and Intellisense accepted the syntax.
There's another bug that can cause this exact error:
Happened to me after changing a property name without refactoring, which caused some linq code to call the namespace itself!
To see the bug in action all you have to do is run this piece of code:
public static int Test()
{
var x = from c in ConsoleApplication5
select 3;
return x.First();
}
Where ConsoleApplication5 is the namespace!
This only happens in VS2015.
Update:
There's an issue for this now on GitHub if anyone's interested.
I got this error when I was working with data table and did not provide a data type where it was required:
bool temp = dtTab.AsEnumerable().Any(row => row.Field<>("active") == 1);
Giving it a proper data type got rid of the error. I also had to convert it to string to be able to compare it correctly-
bool temp = dtTab.AsEnumerable().Any(row => row.Field<Boolean>("active").toString() == "1");
I got this error too, seems like there is some major reasons that cause this error.
I posted this answer to wrap up mentioned solutions and help other guys so they can solve this error quickly
Using obfuscated DLLs by Smart Assembly mentioned on marked answer Solution: Update Smart Assembly to version 6.9
Namespace issue mentioned here, also has open Github issue Here
In my case the problem was this one, Field is strongly-typed, not specifying it, mentioned here
Using Const keyword, mentioned here
Please read all answers here on this page carefully, I'm sure you can solve the issue using one of mentioned solutions, good luck :)
This answer is similar to that posted by #wrtsvkrfm
'Dim NEWLINE As String = "<BR/>"
Dim NEWLINE As String = vbCrLf
Const HT_QTC_VENDOR As String = "<B>some stuff {0}</B>" & NEWLINE
This will cause the DLL to be not emitted,
Change the top 2 lines to
'Const NEWLINE As String = "<BR/>"
Const NEWLINE As String = vbCrLf
and the error goes away.
This should be a compilation error.
A CONST clearly cant depend on a variable, which may..., well..., vary. :-)
I get the same "Failed to emit module" error with this code but changing the "Const" to "Dim" resolves the problem:
Dim userStatus1 As String = convAttrSet("user_status")
Dim userStatus2 As String = convAttrSet("user_status")
Const PENDING As Boolean = (userStatus1 = userStatus2)
I got this error when using linq to entities and my linq query had a syntax error in the join clause
For me the issue occured after adding a postbuild step that changes the assemblyinfo.cs (NetRevisionTool.exe).
Take care to not change the AssemblyInfo.cs between building and Edit and continue.
I also had this exception being thrown in VB.NET (Visual Studio 2015 - Pro), and isolated a single line that was causing the error
Faulty....
Dim i As Short
Dim j As Short = BancoCombienElement(LaChaine)
Const a = (22 / 60) * j
Dim TiTxt As String = ""
Dim S_8_10_12_14 As String = ""
Work good!!!!!!!!
Dim i As Short
Dim j As Short = BancoCombienElement(LaChaine)
Dim a As Short = (22 / 60) * j
Dim TiTxt As String = ""
Dim S_8_10_12_14 As String = ""
Reason:
This error seems to be introduced when we have something weird in our code.
For me I made a mistake while getting the current user from identity.
Error Code:
int currentUserId = User.Identity.GetUserId<>();
Fixed Code:
Please specify the data type after GetUserID<---------->();In this case I have specified int.
Note
Please try to undo your code step by step so that you can find this issue. But otherwise it was very difficult for me track that error.
Thanks
This can happen for any error that the compiler did not catch. Probably
either the compiler doesn't know what IL to emit, or
it knows but in the process of actually doing it, something unexpected happens or
the IL that it emits is invalid and some safety net at a lower level than the compiler itself produces an error that the compiler is not built to handle.
In any case, this CS7038 occurs because the C# is valid and there is a good chance the compiler encountered an error in such an unexpected place that it is no longer able to trace it to any source code line that you wrote. Hence the seemingly random errors that people report here to cause this.
I've used C# for decades and I arrive here now because this is the first time ever I get an error like this.
In my case the following code generates the error. Use <LangVersion>Preview</LangVersion> in the project file and use the C# 8 compiler in Visual Studio 2019 preview.
void FailToEmitDll(ReadOnlySpan<char> span) {
ReadOnlySpan<char> temp;
temp = 1 switch
{
_ => span
};
}
Odd enough, if you change the declaration and the assignment to read like var temp instead, all works well.
Adding to the list of possible causes, in VS2019 with C# 8, I got the "Failed to emit module" message when doing something like:
_ = someBool ? SomeVoid() : default;
I filed a bug report about it here: https://github.com/dotnet/roslyn/issues/41741
I got this error when I run a complex expression in Mock object, I fixed this by store the expression result to local variable.
Related
I need to include double.TryParse(wordConf, out double wordConfDouble); in a script, but I get a feature out variable declaration is not available in c# 6 error message. Searching for it on Google, I can only see solutions for upgrading to C# 7 (which I am not allowed to do so in this project) so I wonder if someone could help me write an equivalent to this line that would work in any C# compiler.
You don't need to inline declare a type for out-parameters.
Replace:
double.TryParse(wordConf, out double wordConfDouble);
With:
double wordConfDouble;
double.TryParse(wordConf, out wordConfDouble);
It's just the inline declaration which is not supported in < C#7.0. Change your code to
double wordConfDouble;
double.TryParse(wordConf, out wordConfDouble);
Reference: https://learn.microsoft.com/en-us/dotnet/csharp/whats-new/csharp-7#out-variables
Recently I came across a code base and found some code like below
var a = 1_23_456;
Console.WriteLine(a);
I have tried to run it in visual studio 2015/ .net fiddle but it got a compilation error. But when I retried it using Roslyn 2.0 compiler, it got compiled and gives me the output 123456.
What the matter here? Why it is showing the data as an integer ?
The underscores are the digit separator. They're used to make it easier to read large numbers (particularly binary numbers). You can read about them on MSDN.
The underscores don't change the datatype. All of the following statements result in the same data type (int or System.Int32) and value:
var a = 123456;
int b = 123456;
System.Int32 c = 123456;
var d = 1_23_456;
int e = 1_23_456;
System.Int32 f = 1_23_456;
You will need the new compiler in Visual Studio 2017 to compile it, though you may be able to get away with using Visual Studio 2015.
I've started trying new features of C# 7 in Visual Studio Enterprise 15 Preview 2. I'm able to run code of other upcoming features like Binary literals, digit separators etc. But the new syntax of initialization of tuples is not working.
Here is my code snippet:
var latLong = new (double lat, double lng) { lat = 0, lng = 0 };
var result = (5, 20);
var result = (count: 5, sum: 20);
I've followed all the steps mentioned in this blog. Just posting this question if anyone else has also come across this issue. Above code results in compilation failures as shown below:
1>Program.cs(18,26,18,27): error CS1031: Type expected
1>Program.cs(18,27,18,33): error CS1525: Invalid expression term 'double'
1>Program.cs(18,34,18,37): error CS1003: Syntax error, ',' expected
1>Program.cs(18,39,18,45): error CS1525: Invalid expression term 'double'
1>Program.cs(18,46,18,49): error CS1003: Syntax error, ',' expected
I was able to figure this out from another link here. If you read through the comments section it is evident that not all new upcoming features of C# have been able to make it to last VS 15 release which was published. Tuple (value types with new declaration syntax) is one such feature.
We might have to wait for RTM build before all features can really start working OR the other way is to get the latest source code of roslyn from its gitHub repository, clone it on your own machine, compile it and make your Visual Studio 15 Preview 2 installation to use it. More latest commit you pull, more features you will get to play with.
You can initialize it this way:
void Main()
{
var latLong = (lat:0, lng:0);
var result1 = (5, 20);
var result2 = (count: 5, sum: 20);
}
To try it, you can either use the fiddle (link at the bottom of this answer), or offline with the LinqPad tool, both support C#7 already.
To view the results, add
latLong.Dump(); result1.Dump(); result2.Dump();
to the example above. All 3 declarations are created as ValueTuple<Int32,Int32>. To create other data types, you need to specify it as explicit type conversion, e.g.
var latLong = (lat:(double)0.5, lng:(double)0);
will create a ValueTuple<Double,Double>. To decompose the tuple, use
var (lat, lng) = latLong;
which will create and assign two variables lat and lng. To find out some more C#7 features, look here.
Try out examples with DotNetFiddle
I'm writing a C# program using Visual Studio 2010 where I want to write out certain events to a log file and include the line number the code was on when that happened.
I've only found two ways of capturing line numbers - CallerLineNumber, which requires .Net 4.5/C#5 (I'm targeting .Net 4) and StackFrame.GetFileLineNumber, which apparently requires a debug build and pdb file to work properly, and I'm producing a release build and no pdb file.
But here's what I don't get - both of the above are run-time solutions, but line numbers are compile-time entities. Why is a runtime solution necessary?
I could type in the correct line number as a literal constant by just looking at the bottom of the screen where it says something like "ln 175" . . .
LogEvent("It happened at line 175");
but the problem with that is that if I edit any code before line 175 my literal might no longer be correct. But the compiler knows the correct line number and I've used programming languages in the past that could just pop in the correct line number as a compile time constant. (e.g., ANSI C and Microsoft C++ support a predefined macro called
_LINE_) Is there any way to get C# to do that? If not are there any solutions to my problem?
CAVEATS: This is NOT an answer to the OP. I know that. But people looking for something similar may find this page.
This is not about .NET 4.
This is still ultimately a run-time solution.
But VS 2015, C#, .NET Core or .NET 4.5 allow:
using System.Runtime.CompilerServices;
using System.Diagnostics;
public static String CurrentLocation(
[CallerFilePath] string file = null,
[CallerLineNumber] int lineNumber = 0,
[CallerMemberName] string method = null)
{
String location = file;
if (lineNumber != 0)
{
location += "(" + lineNumber.ToString() + ")";
}
if (!String.IsNullOrWhiteSpace(method))
{
location += ": " + method;
}
if (!String.IsNullOrWhiteSpace(location))
{
location += ": ";
}
return location;
}
[UPDATED USAGE]
With usage something like:
Console.Error.WriteLine(CurrentLocation() + "some message");
or
Debug.WriteLine(CurrentLocation() + "some message");
No, C# doesn't have a macro preprocessor or any meta programming features, so there are no "Compile time" solutions in the entire language. But there are 3rd party macro languages out there that you can use, if you have to, but of course it complicates the build process, Visual Studio won't just figure out how to built it by itself.
You can even use the C preprocessor if you want it. (assuming MSVC compiler)
cl.exe /TC /P /C /EP something.cs > something.raw.cs
cl.exe is the C compiler
/TC tells the C compiler to treat all files as C sources despite their extensions
/P tells the C compiler to only preprocess the file do not compile it
/C preserves the comments
/EP prevents the compiler from generating #line directives, that the C# compiler wouldn't understand
This will allow you to use #include, #define and #if as well as __FILE__ and __LINE__ in your C# program, but again you have to set up Visual Studio to do this additional compilation step, or use a different build system.
One option would be to use the StackTrace class, like so
[Conditional("DEBUG")]
public static void DebugPrintTrace()
{
StackTrace st = new StackTrace(true);
StackFrame sf = st.GetFrame(1);
Console.WriteLine("Trace "
+ sf.GetFileName() + " "
+ sf.GetMethod().Name + ":"
+ sf.GetFileLineNumber() + "\n");
}
In my opinion, line numbers are the wrong approach. Let me explain:
How unique is line number 175? Even if you find a solution, the next question is: which file was it? And it will repeat: if you know the file, you'll ask yourself: which version of the file was it? And you'll integrate the revision number of your source control system. Once you did that, the question will come up: who was calling that code.
If you're debugging an exception, use a debugger and break on first chance exceptions.
If you're analyzing a performance issue, line numbers don't matter, anything unique will do. Try a memory profiler.
If your methods are too long to identify the problems, refactor your code and make the methods shorter. With short methods, you can use an AOP framework like PostSharp with its logging aspect to achieve at least the CallerMemberName feature. It's available down to .NET 2.0 and it's very easy to add logging and remove logging, not like deleting single lines in your code.
I'm messing around with some windows functions using p/invoke. Occasionally, I get an error code that is not ERROR_SUCCESS (such an odd name).
Is there a way to look these up within the program? Forexample, if I get error 1017. Can I tell the user
The system has attempted to load or
restore a file into the registry, but
the specified file is not in a
registry file format.
(ERROR_NOT_REGISTRY_FILE: 0x3F9)
Instead of
Error Code: 1017
I'm not sure if there's a niifty .NET wrapper, but you could call the FormatMessage API using P/Invoke.
See this answer for how it would normally be called from native code. Though the question refers to grabbing error codes from HRESULTs, the answer also applies for retreiving codes from the regular OS error codes coming from GetLastError/GetLastWin32Error).
EDIT: Thanks Malfist for pointing me to pinvoke.net, which includes alternative, managed API:
using System.ComponentModel;
string errorMessage = new Win32Exception(Marshal.GetLastWin32Error()).Message;
Console.WriteLine(errorMessage);
You could take the defines from winerror.h at Rensselaer Polytechnic Institute, and put them into an Enum:
public enum Win32ErrorCode : long
{
ERROR_SUCCESS = 0L,
NO_ERROR = 0L,
ERROR_INVALID_FUNCTION = 1L,
ERROR_FILE_NOT_FOUND = 2L,
ERROR_PATH_NOT_FOUND = 3L,
ERROR_TOO_MANY_OPEN_FILES = 4L,
ERROR_ACCESS_DENIED = 5L,
etc.
}
Then if your error code is in a variable error_code you would use :
Enum.GetName(typeof(Win32ErrorCode), error_code);
I landed on this page while in search of a managed alternative to calling FormatMessage through P/Invoke.
As others have said, there is no way to get those capitalized, underscored names, short of looking them up in winerror.h, which I have seen reproduced online in various places where I landed in the course of searching for information about resolving specific status codes. A quick Google search, for winerror.h, itself, uncovered a page, at Rensselaer Polytechnic Instutute, where someone has helpfully extracted the #define statements from it.
Looking at it gave me an idea; I think there may be a way to get there, working from the source code of winerror.h, which I have, as part of the Windows Platform SDK that ships with every recent version of Microsoft Visual Studio.
Right now, I am in the middle of sorting out a pressing issue in the .NET assembly that brought me to this page. Then, I'll see what I can cobble together; this kind of challenge is right up my alley, and somebody threw down a gauntlet.
Yes there's a function that does that but I don't remember what it is. In the mean time, you can use the error lookup tool (Tools->Error Lookup) to see what a particular code means from within Visual Studio.