# add\_library, sources as list not producing DLL, no error either

**URL:** <https://discourse.cmake.org/t/add-library-sources-as-list-not-producing-dll-no-error-either/8922>\
**Category:** Code\
**Created:** [September 10, 2023, 6:13pm UTC](https://discourse.cmake.org/t/add-library-sources-as-list-not-producing-dll-no-error-either/8922 "2023-09-10T18:13:49Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Kirk\_Morgan](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/k/c0e974/32.png) [@Kirk\_Morgan](https://discourse.cmake.org/u/Kirk_Morgan)\
**Post date:** [September 10, 2023, 6:13pm UTC](https://discourse.cmake.org/t/add-library-sources-as-list-not-producing-dll-no-error-either/8922/1 "2023-09-10T18:13:49Z")

</div>

Hi,

I’m trying to write a CMakeLists.txt file in VS Code using the Microsoft C compiler to make a DLL target. I never learned ‘make’ files the hard way so you may need to explain me some dumb. But I did get my whole process to run in command line (without CMake) and produce the DLL I want. I would just prefer to learn the VSCode / CMake method so I can grow things later.

For my project I want to use a list of source files in the add\_library() command. But I can’t get the list to work in both of two different ways. I only seem to be able to make add\_library() work with the sources hard-coded in that call. I know about the wisdom of not having target source lists that can change in a CMakeLists.txt file and I have a grasp of that issue I think as you might tell below. I want to be able to use a list for just ease of management / edits.

The DLL created will be used by an .EXE from some vendor. The vendor gives a library to link against a header file to use each time in my own C source files.

For the CMakeLists.txt, when I hard-code my source file paths in add\_library (separated by spaces) and then Build the project with the corresponding .vcxproj, I get the DLL and it works as mentioned. I am keeping the vendor library and header file in the vendor folder - NOT at my project folder (is this a problem???) - but, like I said, it works with add\_library() and the sources hard-coded.

Under all scenarios I can check the sources of the target. The returned value is a list and I can query those items and they match my input.

But when I use the list in the add\_library() though a couple things happen. First is I get an error that CMake can’t figure out the linker language. I can solve this error by setting that property for the target. Second is that - although the BUILD runs without error stated - I GET NO DLL. Below is my two different setups. Can you tell what’s wrong? Do you need the whole file? I’m running CMake Version 3.27.4. Thank you.

Kirk Morgan

PS I am detecting that capitalization may play a role. How would I tell? My file names were capitalized in Windows OS at draft time of this note.

PPS Can someone please confirm my request for discourse account was received and e-mail sent to my mail account? I tried this account and my gmail but the confirm invitations don’t come through. Thank you.

# 

# this (which Build ‘without error’ won’t give a DLL)

# 

```cmake
file(GLOB SOURCES CONFIGURE_DEPENDS "*.C")
add_library(userpack SHARED ${SOURCES})
set_target_properties(userpack PROPERTIES LINKER_LANGUAGE C)

```

# 

# nor these (which also Build ‘without error’ but won’t give a DLL either)

# 

```cmake
# variant 1/2
list(APPEND SOURCES ${CMAKE_SOURCE_DIR}/REALSUM.C ${CMAKE_SOURCE_DIR}/TRNSPOSE.C ${CMAKE_SOURCE_DIR}/USERPACK.C)
# variant 2/2
list(APPEND SOURCES REALSUM.C TRNSPOSE.C USERPACK.C)

add_library(userpack SHARED ${SOURCES})
set_target_properties(userpack PROPERTIES LINKER_LANGUAGE C)

```

# 

# versus this (which works)

# 

```cmake
#Make the target and put the sources on it
add_library(userpack SHARED realsum.c trnspose.c userpack.c )

```

#

---

<div class="post-metadata">

**Author:** ![ben.boeckel](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)\
**Post date:** [September 13, 2023, 3:05am UTC](https://discourse.cmake.org/t/add-library-sources-as-list-not-producing-dll-no-error-either/8922/2 "2023-09-13T03:05:52Z")

</div>

> [@Kirk\_Morgan](#):
>
> First is I get an error that CMake can’t figure out the linker language

This tends to mean that CMake didn’t recognize any compilable sources in the target for which to compute it on its own.

I suspect the problem here is that you have `.C` extensions which is, by default, indicative of C++ sources. Given that C++ is enabled by default, I think you have `project(userpack LANGUAGES C)` and only enable C and therefore disabling C++. These `.C` files then get classified as C++ and, without C++ support, are not compilable.

You can keep the names and do something like this:

```cmake
set_source_files_properties(${SOURCES} PROPERTIES LANGUAGE C)

```

to override the automatic detection and force them to be considered C files.