Unnecessary project rebuilds when unit testing in Visual Studio - unit-testing

I know about this question (and answers), but despite trying all the suggested options I am still stuck.
I have a solution with multiple projects, but for this particular case let's say I've got my ExampleProjectA and a corresponding unit test project ExampleProjectATest. The first one is added as a reference to the test project - not via Visual Studio's "Project References" but as a link to the DLL (something like "..\Path\$(Config)\ExampleProjectA.dll") - this is due to build server requirements in our company, but the problem also existed when we still had "Project References".
Building and then running a single unit test works fine
Changing just a single letter in a unit test and then letting the test run always results in a rebuild of ExampleProjectA, even though this shouldn't be necessary
Setting all (there were only a few) files in ExampleProjectA from "Copy always" to "Copy if newer" in their respective properties didn't help
Checking the checkbox under Tools => Options => Projects and Solutions => Build an Run (see below) also didn't change anything
To see if there was any more information available, I changed the build output settings to diagnostic. Each time a rebuild of ExampleProjectA is triggered, the first line in the output windows is
1>Project 'ExampleProjectATest' is not up to date. Input file 'c:\tfs\mysolution-dev\exampleprojectatest\myfolder\namegeneratortest.cs' is modified after output file 'C:\tfs\mysolution-dev\exampleprojectatest\bin\Release\exampleprojectatest.pdb'.
The class name written to the window (e.g. namegeneratortest.cs) changes according to which test file I change.
Not sure why this message comes up, but the next step was to disable the debugging information as shown below under Project properties => Build => Advanced => Output => Debug Info => None:
Still the same, nothing's changed.
Another thing I tried was to check the timestamps of the files contained in my solution folder (as there was a case where a user had a file with a future timestamp - see linked post) - to no avail.
Last thing I tried was to change the build settings in the Configuration Manager to a different target platform - some settings wouldn't let me build the solution successfully, some other settings did, but the problem described persisted, so no change.
The behaviour is similar (not the same though) with both the Visual Studio Test Runner and the one provided by ReSharper.
Visual Studio Test Runner
Project 'ExampleProject' is not up to date. Input file 'C:\tfs\mysolution-dev\exampleprojecta\Views\Shared\someview.cshtml' is modified after output file 'C:\tfs\mysolution-dev\exampleprojecta\bin\exampleprojecta.pdb'.
ReSharper Test Runner
Project 'ExampleProjectATest' is not up to date. Input file 'c:\tfs\mysolution-dev\exampleprojectatest\myfolder\namegeneratortest.cs' is modified after output file 'C:\tfs\mysolution-dev\exampleprojectatest\bin\Release\exampleprojectatest.pdb'.
I'm using Visual Studio 2013 Premium Edition with ReSharper 8.2 and the latest updates, the projects in our solution file are in C#.
Update
To clarify - the first line in the output window does show that the test project has to be rebuilt - this is fine. The following lines, however, indicate that also ExampleProjectA has to be rebuilt, which shouldn't be necessary. Subsequent messages to the output window also show that other projects (referenced from ExampleProjectA have to be rebuilt.
Update 2
Despite installing Update 4, nothing has changed.

For my case the solution was to change the build action of a config file from "Copy always" to "Copy if newer". It took a while to find as I had to change the build output details to get the details about which file was causing the error, e.g.
Project 'xyz' is not up to date. Project item 'c:\my\path\web.config.dev' has 'Copy to Output Directory' attribute set to 'Copy always'.
From my experience it can also happen that different file names are shown when building multiple times, so make sure you have the right one and / or build again if the problem persists.
Also have a look at this question and its answers to find some more information.

I have worked around this problem by deleting the .pdb file in the \obj folder. It seems that visual studio is checking file modification time to decide if it should build or not the project (in your case ExampleProjectA) and the .cshtml is newer than the pdb. But when launching the build, project changes in .cshtml files are not triggering the .pdb rebuild, so the problem remains.
By deleting the .pdb in \obj folder (not in \bin as the file there is copied from \obj and would keep the old modification time) the modification time for the .pdb is newer than the .cshtml and the VS doesn't need to build the project before running the tests. Of course this only works until the next time you modify a .cshtml file, that's why I qualify it as just a workaround.

Check what version of Visual Studio 2013 you are using. Update 1 has a pretty big issue where it rebuilds everything. See: https://connect.microsoft.com/VisualStudio/feedback/details/811112/unnecessary-solution-rebuild-on-each-test-run
Upgrading to Update 3 did the trick!
I'm not sure if Resharper could affect things as well. I suggest temporarily uninstalling it.

Related

Visual Studio 2019 Debugger "Unable to start program ... Access is denied" caused by build file [duplicate]

I have a solution in C:\full path here\VS2010\blender.sln
This solution contains many projects(around 100). When I compile them, they all work fine. I can run them without any problem, and (quite) everything works (there are some bugs).
One of the projects is ALL_BUILD, but it gives the same error if I try to debug INSTALL(another project). I'm compiling with RELWithDebInfo as configuration, and if I execute the program manually it works. It is outputted in C:\full path here\VS2010\bin\RelWithDebInfo
But if I try to run the compiler, it says
"Unable to start program
C:\full path here\VS2010\RelWithDebInfo\ALL_BUILD
Specified file cannot be found"
I tried to copy the compiled program into the path required by VS, but it raised the same error.
What should I do to solve this? Right now I set up cmake to generate also a mingw project and I compile it and debug it with gdb, but this is a really a slow and impractical workflow, and I would like to use the VS debugger.
I must say that if I compile with Debug as configuration, the program doesn't even start.
I'm using VS2010 Express on Win7 64bit
(This is a big open source program, so I don't know exactly whatever it does)
Guessing from the information I have, you're not actually compiling the program, but trying to run it. That is, ALL_BUILD is set as your startup project. (It should be in a bold font, unlike the other projects in your solution) If you then try to run/debug, you will get the error you describe, because there is simply nothing to run.
The project is most likely generated via CMAKE and included in your Visual Studio solution. Set any of the projects that do generate a .exe as the startup project (by right-clicking on the project and selecting "set as startup project") and you will most likely will be able to start those from within Visual Studio.
I had the same problem :)
Verify the "Source code" folder on the "Solution Explorer", if it doesn't contain any "source code" file then :
Right click on "Source code" > Add > Existing Item > Choose the file You want to build and run.
Good luck ;)
I think that what you have to check is:
if the target EXE is correctly configured in the project settings ("command", in the debugging tab). Since all individual projects run when you start debugging it's well possible that only the debugging target for the "ALL" solution is missing, check which project is currently active (you can also select the debugger target by changing the active project).
dependencies (DLLs) are also located at the target debugee directory or can be loaded (you can use the "depends.exe" tool for checking dependencies of an executable or DLL).

Visual Studio 2015 C++ solution can't see svn exe in system PATH

Our team has two separate Visual Studio 2015 C++ projects, which are very similar in terms of project layout, Pre-Build Events etc.
In the Pre-Build Events of the startup project in each solution, an attempt is made to call an exe (svn) in the system PATH.
In solution 1, this works fine, and can execute the svn command.
In solution 2 however, it can't see svn on the PATH.
I've checked and found the following:
the Pre-Build Event is identical in each solution
i've compared the .vcxproj files for each Solution and there's nothing apparent
the full path to the VS Solution that works is longer than the one that doesn't work (so no max file path length issues)
there are no spaces in the full path names
So my question is, why might one Visual Studio solution be able to see an exe on the PATH, while another with similar layout, can't?
Thanks
#Lightness Races in Orbit was correct - I had missed something.
My vcxproj files had different entries for the Project that could see SVN compared to the Project that couldn't see it.
The culprit was the ExecutablePath Property.
Copying the entry from the vcxproj file for the working Project to the non-working Project allowed the latter to finally find SVN in the PATH.

How to find inexistant files in the project [duplicate]

I have a very similar problem as described here.
I also upgraded a mixed solution of C++/CLI and C# projects from Visual Studio 2008 to Visual Studio 2010. And now in Visual Studio 2010 one C++/CLI project always runs out of date.
Even if it has been compiled and linked just before and F5 is hit, the messagebox "The project is out of date. Would you like to build it?" appears. This is very annoying because the DLL file is very low-tiered and forces almost all projects of the solution to rebuild.
My pdb settings are set to the default value (suggested solution of this problem).
Is it possible the get the reason why Visual Studio 2010 forces a rebuild or thinks a project is up to date?
Any other ideas why Visual Studio 2010 behaves like that?
For Visual Studio/Express 2010 only. See other (easier) answers for VS2012, VS2013, etc
To find the missing file(s), use info from the article Enable C++ project system logging to enable debug logging in Visual Studio and let it just tell you what's causing the rebuild:
Open the devenv.exe.config file (found in %ProgramFiles%\Microsoft Visual Studio 10.0\Common7\IDE\ or in %ProgramFiles(x86)%\Microsoft Visual Studio 10.0\Common7\IDE\). For Express versions the config file is named V*Express.exe.config.
Add the following after the </configSections> line:
<system.diagnostics>
<switches>
<add name="CPS" value="4" />
</switches>
</system.diagnostics>
Restart Visual Studio
Open up DbgView and make sure it's capturing debug output
Try to debug (hit F5 in Visual Studio)
Search the debug log for any lines of the form:
devenv.exe Information: 0 : Project 'Bla\Bla\Dummy.vcxproj' not up to date because build input 'Bla\Bla\SomeFile.h' is missing.
(I just hit Ctrl+F and searched for not up to date) These will be the references causing the project to be perpetually "out of date".
To correct this, either remove any references to the missing files from your project, or update the references to indicate their actual locations.
Note: If using 2012 or later then the snippet should be:
<system.diagnostics>
<switches>
<add name="CPS" value="Verbose" />
</switches>
</system.diagnostics>
In Visual Studio 2012 I was able to achieve the same result easier than in the accepted solution.
I changed the option in menu Tools → Options → Projects and Solutions → Build and Run → *MSBuild project build output verbosity" from Minimal to Diagnostic.
Then in the build output I found the same lines by searching for "not up to date":
Project 'blabla' is not up to date. Project item 'c:\foo\bar.xml' has 'Copy to Output Directory' attribute set to 'Copy always'.
This happened to me today. I was able to track down the cause: The project included a header file which no longer existed on disk.
Removing the file from the project solved the problem.
We also ran into this issue and found out how to resolve it.
The issue was as stated above "The file no longer exists on the disk."
This is not quite correct. The file does exist on the disk, but the .VCPROJ file is referencing the file somewhere else.
You can 'discover' this by going to the "include file view" and clicking on each include file in turn until you find the one that Visual Studio can not find. You then ADD that file (as an existing item) and delete the reference that can not be found and everything is OK.
A valid question is: How can Visual Studio even build if it does not know where the include files are?
We think the .vcproj file has some relative path to the offending file somewhere that it does not show in the Visual Studio GUI, and this accounts for why the project will actually build even though the tree-view of the includes is incorrect.
The accepted answer helped me on the right path to figuring out how to solve this problem for the screwed up project I had to start working with. However, I had to deal with a very large number of bad include headers. With the verbose debug output, removing one caused the IDE to freeze for 30 seconds while outputting debug spew, which made the process go very slowly.
I got impatient and wrote a quick-and-dirty Python script to check the (Visual Studio 2010) project files for me and output all the missing files at once, along with the filters they're located in. You can find it as a Gist here: https://gist.github.com/antiuniverse/3825678 (or this fork that supports relative paths)
Example:
D:\...> check_inc.py sdk/src/game/client/swarm_sdk_client.vcxproj
[Header Files]:
fx_cs_blood.h (cstrike\fx_cs_blood.h)
hud_radar.h (cstrike\hud_radar.h)
[Game Shared Header Files]:
basecsgrenade_projectile.h (..\shared\cstrike\basecsgrenade_projectile.h)
fx_cs_shared.h (..\shared\cstrike\fx_cs_shared.h)
weapon_flashbang.h (..\shared\cstrike\weapon_flashbang.h)
weapon_hegrenade.h (..\shared\cstrike\weapon_hegrenade.h)
weapon_ifmsteadycam.h (..\shared\weapon_ifmsteadycam.h)
[Source Files\Swarm\GameUI - Embedded\Base GameUI\Headers]:
basepaenl.h (swarm\gameui\basepaenl.h)
...
Source code:
#!/c/Python32/python.exe
import sys
import os
import os.path
import xml.etree.ElementTree as ET
ns = '{http://schemas.microsoft.com/developer/msbuild/2003}'
#Works with relative path also
projectFileName = sys.argv[1]
if not os.path.isabs(projectFileName):
projectFileName = os.path.join(os.getcwd(), projectFileName)
filterTree = ET.parse(projectFileName+".filters")
filterRoot = filterTree.getroot()
filterDict = dict()
missingDict = dict()
for inc in filterRoot.iter(ns+'ClInclude'):
incFileRel = inc.get('Include')
incFilter = inc.find(ns+'Filter')
if incFileRel != None and incFilter != None:
filterDict[incFileRel] = incFilter.text
if incFilter.text not in missingDict:
missingDict[incFilter.text] = []
projTree = ET.parse(projectFileName)
projRoot = projTree.getroot()
for inc in projRoot.iter(ns+'ClInclude'):
incFileRel = inc.get('Include')
if incFileRel != None:
incFile = os.path.abspath(os.path.join(os.path.dirname(projectFileName), incFileRel))
if not os.path.exists(incFile):
missingDict[filterDict[incFileRel]].append(incFileRel)
for (missingGroup, missingList) in missingDict.items():
if len(missingList) > 0:
print("["+missingGroup+"]:")
for missing in missingList:
print(" " + os.path.basename(missing) + " (" + missing + ")")
I've deleted a cpp and some header files from the solution (and from the disk) but still had the problem.
Thing is, every file the compiler uses goes in a *.tlog file in your temp directory.
When you remove a file, this *.tlog file is not updated. That's the file used by incremental builds to check if your project is up to date.
Either edit this .tlog file manually or clean your project and rebuild.
I had a similar problem, but in my case there were no files missing, there was an error in how the pdb output file was defined: I forgot the suffix .pdb (I found out with the debug logging trick).
To solve the problem I changed, in the vxproj file, the following line:
<ProgramDataBaseFileName>MyName</ProgramDataBaseFileName>
to
<ProgramDataBaseFileName>MyName.pdb</ProgramDataBaseFileName>
I had this problem in VS2013 (Update 5) and there can be two reasons for that, both of which you can find by enabling "Detailed" build output under "Tools"->"Projects and Solutions"->"Build and Run".
"Forcing recompile of all source files due to missing PDB "..."
This happens when you disable debug information output in your compiler options (Under Project settings: „C/C++“->“Debug Information Format“ to „None“ and „Linker“->“Generate Debug Info“ to „No“: ). If you have left „C/C++“->“Program Database File Name“ at the default (which is „$(IntDir)vc$(PlatformToolsetVersion).pdb“), VS will not find the file due to a bug (https://connect.microsoft.com/VisualStudio/feedback/details/833494/project-with-debug-information-disabled-always-rebuilds).
To fix it, simply clear the file name to "" (empty field).
"Forcing rebuild of all source files due to a change in the command line since the last build."
This seems to be a known VS bug too (https://connect.microsoft.com/VisualStudio/feedback/details/833943/forcing-rebuild-of-all-source-files-due-to-a-change-in-the-command-line-since-the-last-build) and seems to be fixed in newer versions (but not VS2013). I known of no workaround, but if you do, by all means, post it here.
I don't know if anyone else has this same problem, but my project's properties had "Configuration Properties" -> C/C++ -> "Debug Information Format" set to "None", and when I switched it back to the default "Program Database (/Zi)", that stopped the project from recompiling every time.
Another simple solution referenced by Visual Studio Forum.
Changing configuration: menu Tools → Options → Projects and Solutions → VC++ Project Settings → Solution Explorer Mode to Show all files.
Then you can see all files in Solution Explorer.
Find the files marked by the yellow icon and remove them from the project.
It's OK.
Visual Studio 2013 -- "Forcing recompile of all source files due to missing PDB". I turned on detailed build output to locate the issue: I enabled "Detailed" build output under "Tools" → "Projects and Solutions" → "Build and Run".
I had several projects, all C++, I set the option for under project settings: (C/C++ → Debug Information Format) to Program Database (/Zi) for the problem project. However, this did not stop the problem for that project. The problem came from one of the other C++ projects in the solution.
I set all C++ projects to "Program Database (/Zi)". This fixed the problem.
Again, the project reporting the problem was not the problem project. Try setting all projects to "Program Database (/Zi)" to fix the problem.
I met this problem today, however it was a bit different. I had a CUDA DLL project in my solution. Compiling in a clean solution was OK, but otherwise it failed and the compiler always treated the CUDA DLL project as not up to date.
I tried the solution from this post.
But there is no missing header file in my solution. Then I found out the reason in my case.
I have changed the project's Intermediate Directory before, although it didn't cause trouble. And now when I changed the CUDA DLL Project's Intermediate Directory back to $(Configuration)\, everything works right again.
I guess there is some minor problem between CUDA Build Customization and non-default Intermediate Directory.
I had similar problem and followed the above instructions (the accepted answer) to locate the missing files, but not without scratching my head. Here is my summary of what I did. To be accurate these are not missing files since they are not required by the project to build (at least in my case), but they are references to files that don't exist on disk which are not really required.
Here is my story:
Under Windows 7 the file is located at %ProgramFiles(x86)%\Microsoft Visual Studio 10.0\Common7\IDE\%. There are two similar files devenv.exe.config.config and devenv.exe.config. You want to change later one.
Under Windows 7, you don't have permission to edit this file being in program files. Just copy it somewhere else (desktop) change it and than copy it back to the program files location.
I was trying to figure out how to connect DebugView to the IDE to see the missing files. Well, you don't have to do anything. Just run it, and it will capture all the messages. Make sure Capture Events menu option is selected in Capture menu which by default should be selected.
DebugView will NOT display all the missing files at once (at least it didn't for me)! You would have DebugView running and than run the project in Visual Studio 2010. It will prompt the project out of date message, select Yes to build and DebugView will show the first file that is missing or causing the rebuild. Open the project file (not solution file) in Notepad and search for that file and delete it. You are better off closing your project and reopening it again while doing this delete. Repeat this process until DebugView no longer shows any files missing.
It's kind of helpful to set the message filter to not up to date from the DebugView toolbar button or Edit → Filter/Highlight option. That way the only messages it displays are the one that has `not up to date' string in it.
I had lots of files that were unnecessary references and removing them all fixed the issue following the above steps.
Second way to find all the missing files at once
There is a second way to find these files all at once, but it involves (a) source control and (b) integration of it with Visual Studio 2010. Using Visual Studio 2010, add your project to a desired location or dummy location in source control. It will try to add all the files, including those that don't exist on disk as well but referenced in the project file. Go to your source control software like Perforce, and it should mark these files which don't exist on disk in a different color scheme. Perforce shows them with a black lock on them. These are your missing references. Now you have a list of them all, and you can delete all of them from your project file using Notepad and your project would not complain about being out of date.
For me it was the presence of a non-existing header file on "Header Files" inside the project. After removing this entry (right-click > Exclude from Project) first time recompiled, then directly
========== Build: 0 succeeded, 0 failed, 5 up-to-date, 0 skipped ==========
and no attempt of rebuilding without modification was done. I think is a check-before-build implemented by VS2010 (not sure if documented, could be) which triggers the "AlwaysCreate" flag.
If you are using the command-line MSBuild command (not the Visual Studio IDE), for example if you are targetting AppVeyor or you just prefer the command line, you can add this option to your MSBuild command line:
/fileLoggerParameters:LogFile=MyLog.log;Append;Verbosity=diagnostic;Encoding=UTF-8
As documented here (warning: usual MSDN verbosity). When the build finishes, search for the string will be compiled in the log file created during the build, MyLog.log.
I'm using Visual Studio 2013 Professional with Update 4 but didn't find resolution with any of the other suggestions, however, I did manage to resolve the issue for my Team project.
Here's what I did to cause the problem -
Created a new class object (Project -> Add Class)
Renamed the file via Solution Explorer and clicked yes when asked if I wanted to automatically rename all references to match
Here's what I did to solve the problem -
Go to Team Explorer Home
Click Source Control Explorer
Drill into the folder where all of the class/project files are
Found the ORIGINAL filename in the list and deleted it via right-click
Build
If this is the case for you then just be extra sure that you're deleting the phantom file rather than the actual one you want to keep in the project.
I had this problem and found this:
http://curlybrace.blogspot.com/2005/11/visual-c-project-continually-out-of.html
Visual C++ Project continually out-of-date (winwlm.h macwin32.h rpcerr.h macname1.h missing)
Problem:
In Visual C++ .Net 2003, one of my projects always claimed to be out of date, even though nothing had changed and no errors had been reported in the last build.
Opening the BuildLog.htm file for the corresponding project showed a list of PRJ0041 errors for these files, none of which appear on my system anywhere:
winwlm.h macwin32.h rpcerr.h macname1.h
Each error looks something like this:
MyApplication : warning PRJ0041 : Cannot find missing dependency 'macwin32.h' for file 'MyApplication.rc'.
Your project may still build, but may continue to appear out of date until this file is found.
Solution:
Include afxres.h instead of resource.h inside the project's .rc file.
The project's .rc file contained "#include resource.h". Since the resource compiler does not honor preprocessor #ifdef blocks, it will tear through and try to find include files it should be ignoring. Windows.h contains many such blocks. Including afxres.h instead fixed the PRJ0041 warnings and eliminated the "Project is out-of-date" error dialog.
In my case one of the projects contains multiple IDL files. The MIDL compiler generates a DLL data file called 'dlldata.c' for each of them, regardless of the IDL file name. This caused Visual Studio to compile the IDL files on every build, even without changes to any of the IDL files.
The workaround is to configure a unique output file for each IDL file (the MIDL compiler always generates such a file, even if the /dlldata switch is omitted):
Right-click the IDL file
Select Properties - MIDL - Output
Enter a unique file name for the DllData File property
I spent many hours spent tearing out my hair over this. The build output wasn't consistent; different projects would be "not up to date" for different reasons from one build to the next consecutive build.
I eventually found that the culprit was DropBox (3.0.4). I junction my source folder from ...\DropBox into my projects folder (not sure if this is the reason), but DropBox somehow "touches" files during a build. Paused syncing and everything is consistently up-to-date.
There are quite a few potential reasons and - as noted - you need to first diagnose them by setting MSBuild verbosity to 'Diagnostic'. Most of the time the stated reason would be self explanatory and you'd be able to act on it immediatelly, BUT occasionally MSBuild would erroneously claim that some files are modified and need to be copied.
If that is the case, you'd need to either disable NTFS tunneling or duplicate your output folder to a new location. Here it is in more words.
This happened to me multiple times and then went away, before I could figure out why. In my case it was:
Wrong system time in the dual boot setup!
Turns out, my dual boot with Ubuntu was the root cause!! I've been too lazy to fix up Ubuntu to stop messing with my hardware clock. When I log into Ubuntu, the time jumps 5 hours forward.
Out of bad luck, I built the project once, with the wrong system time, then corrected the time. As a result, all the build files had wrong timestamps, and VS would think they are all out of date and would rebuild the project.
Most build systems use data time stamps to determine when rebuilds should happen - the date/time stamp of any output files is checked against the last modified time of the dependencies - if any of the dependencies are fresher, then the target is rebuilt.
This can cause problems if any of the dependencies somehow get an invalid data time stamp as it's difficult for the time stamp of any build output to ever exceed the timestamp of a file supposedly created in the future :P
For me, the problem arose in a WPF project where some files had their 'Build Action' property set to 'Resource' and their 'Copy to Output Directory' set to 'Copy if newer'. The solution seemed to be to change the 'Copy to Output Directory' property to 'Do not copy'.
msbuild knows not to copy 'Resource' files to the output - but still triggers a build if they're not there. Maybe that could be considered a bug?
It's hugely helpful with the answers here hinting how to get msbuild to spill the beans on why it keeps building everything!
If you change the Debugging Command arguments for the project, this will also trigger the project needs to be rebuilt message. Even though the target itself is not affected by the Debugging arguments, the project properties have changed. If you do rebuild though, the message should disappear.
I had a similar issue with Visual Studio 2005, and my solution consisted of five projects in the following dependency (first built at top):
Video_Codec depends on nothing
Generic_Graphics depends on Video_Codec
SpecificAPI_Graphics depends on Generic_Graphics
Engine depends on Specific_Graphics
Application depends on Engine.
I was finding that the Video_Codec project wanted a full build even after a full clean then rebuild of the solution.
I fixed this by ensuring the pdb output file of both the C/C++ and linker matched the location used by the other working projects. I also switched RTTI on.
Another one on Visual Studio 2015 SP3, but I have encountered a similar issue on Visual Studio 2013 a few years back.
My issue was that somehow a wrong cpp file was used for precompiled headers (so I had two cpp files that created the precompiled headers). Now why did Visual Studio change the flags on the wrong cpp to 'create precompiled headers' without my request I have no clue, but it did happen... maybe some plugin or something???
Anyway, the wrong cpp file includes the version.h file which is changed on every build. So Visual Studio rebuilds all headers and because of that the whole project.
Well, now it's back to normal behavior.
I had a VC++ project that was always compiling all files and had been previously upgraded from VS2005 to VS2010 (by other people). I found that all cpp files in the project except StdAfx.cpp were set to Create (/Yc) the precompiled header. I changed this so that only StdAfx.cpp was set to create the precompiled header and the rest were set to Use (/Yu) the precompiled header and this fixed the problem for me.
I'm on Visual Studio 2013 and just updated to the Windows 10 May 2019 update and compiling suddenly had to be redone every time, regardless of changes. Tried renaming the pch to ProjectName instead of TargetName, looked for missing files with the detailed log and that Python script, but in the end it was my time was not synced with MS's servers (by like milliseconds).
What resolved this for me was
"Adjust date and time" in the control panel
"Sync Now"
Now my projects don't need to be recompiled for no reason.
I think that you placed some newline or other whitespace. Remove it and press F5 again.
The .NET projects are always recompiled regardless. Part of this is to keep the IDE up to date (such as IntelliSense). I remember asking this question on an Microsoft forum years ago, and this was the answer I was given.

PostBuild runs always even when all is up to date

I have a VisualStudio 2010 solution containing a lot of C++ projects (above 100).
Many of them with some lines in the PostBuild Event (file copying and more).
The problem occurs when building the solution on our build machine using a tfs build definition:
Even if a project is up to date, the post build executes, and a line with "Creating ".unsuccessfulbuild" because "AlwaysCreate" was specified" is written to the log file. This increases the build time quite a lot and makes Continous Integration build difficult.
This PostBuild is not triggered when running from VisualStudio.
To narrow down the problem (and exclude any possible problem with reference to unexistent files and so on), I created a new solution file, and added a new C++ console application project to the solution using the VisualStudio project wizard. The only thing I changed from default was this line in the PostBuild event: echo "PostBuild Output" (just to see in the log file when the PostBuild was triggered).
Then I created a new Build Definition running this solution.
And still the PostBuild is activated even if the project is up to date. The same problem happens if I build the solution file running msbuild in a command window. But building from VisualStudio works perfect.
Can anyone give me some advice on how to avoid this PostBuild when the project is 'up to date'?
(I have checked that Linker OutputPath matches the $(TargetPath) setting when building on the build machine.)

Visual Studio: Run C++ project Post-Build Event even if project is up-to-date

In Visual Studio (2008) is it possible to force the Post-Build Event for a C++ project to run even if the project is up-to-date?
Specifically, I have a project which builds a COM in-process server DLL. The project has a post-build step which runs "regsvr32.exe $(TargetPath)". This runs fine on a "Rebuild", but runs on a "Build" only if changes have been made to the project's source.
If I do a "Build" without making any changes, Visual Studio simply reports that the project is up-to-date and does nothing - the Post-Build Event is not run. Is there any way that I can force the Event to run in this situation? This is necessary since although the DLL itself is up-to-date, the registration information may not be.
You can use the Custom Build Step property page to set up a batch file to run. This runs if the File specified in the Outputs setting is not found, or is out-of-date. Simply specify some non-existent file there, and the custom build step will always run. It will run even if your project is up-to-date, since the Output file is never found.
Use this DisableFastUpToDateCheck
See an example:
<PropertyGroup>
<PostBuildEvent>IF EXIST C:\Projects\Copy_Files_To_Instance.ps1 ( powershell -file C:\Projects\Copy_Files_To_Instance.ps1)</PostBuildEvent>
<DisableFastUpToDateCheck>true</DisableFastUpToDateCheck>
The registration information is determined largely by what's in the .rgs file. If that file changes the project will get built. I am not sure how else COM registration can change without making the project dirty. Do you mind providing more details about your particular situation?
In Visual Studio 2017 (perhaps other versions as well), for C# projects (haven't checked for C++ projects per OP's actual question) there is an option for "Run the post-build event:", and one option is "Always", which will run the Post-Build even if nothing has changed, rather than simply reporting that the project is up to date: