How do I link Rusqlite applications against custom SQLite builds on Windows?

I want to use a custom-built SQLite library with Rusqlite bindings while building a Rust-coded database application. I am interested in both dynamic and static linking options. The Rusqlite README states that linking to SQLite on Windows is possible via a vcpkg package but does not provide instructions (I do not want to use vcpkg or any other "helper").

The Rust website suggests using the Rust toolset and the Visual Studio C++ Build Tools. Rusqlite's example "persons" can be built via:

{repo-root}> cargo build --example persons --features bundled
or
{repo-root}> cargo build --example persons --features bundled-full

I can build the "persons" example and run it successfully (and other simple examples) via these commands. They create a statically linked executable in "{repo root}\target\debug\examples" using the copy of SQLite included with the library.

The commands

{repo-root}> cargo build --example persons
and
{repo-root}> cargo build --example persons --features modern-full

expectedly fail due to missing sqlite3.lib. What options are available?

Rusqlite repository includes a copy of SQLite amalgamation file (sqlite3.c) and the associated header file (sqlite3.h) inside the "{repo-root}\libsqlite3-sys" directory. Perhaps the simplest starting for testing dynamic linking is to download x64 "Precompiled Binaries for Windows" and use it with the Rusqlite project.

Precompiled SQLite binary

Download the archive and extract it into the "sqlite" directory placed next to the "rusqlite" directory, containing a cloned/downloaded copy of the Rusqlite repository. The "sqlite" directory should contain two files, sqlite3.dll and sqlite3.def. The sqlite3.lib file necessary for the linker can be generated from these two files. Open a "cmd" console with the building (Rust/MSBuild) environment set, change into the "sqlite" directory, and execute this command:

...sqlite> lib /MACHINE:x64 /DEF:sqlite3.def

which should create two new files, including sqlite3.lib. Now change into the "rusqlite" directory, cd ..\rusqlite. The location of "sqlite3.lib" can be passed to the linker via the SQLITE3_LIB_DIR environment variable. Executing

...rusqlite> (set "SQLITE3_LIB_DIR=..\sqlite") && cargo build --example persons
or
...rusqlite> (set "SQLITE3_LIB_DIR=..\sqlite") && cargo build --example persons --features modern-full

should complete successfully and generate "persons.exe" in the "{repo root}\target\debug\examples". There are several possible ways to verify the result before executing it. For example, the Far Manager has the ImpEx plugin (also available from Far PlugRing) that provides convenient access to executable metadata. The list of top-level items seen in ImpEx for "persons.exe" should contain the "64BIT" file-like item and the "Imports Table" directory, among other things. Opening the latter should list several directory-like items named after the imported DLL files, including one for sqlite3.dll.

Also note that the size of the new persons.exe executable is significantly smaller, as it no longer integrates the SQLite library code. Now copy the sqlite3.dll file inside the directory containing persons.exe, for example:

...rusqlite> cd target\debug\examples
...examples> copy /Y ..\..\..\..\sqlite\sqlite3.dll .

and run persons.exe, which should now produce the output as before.

Build SQLite from source

One step further would be to build the SQLite library from the official amalgamation release. Remove the previously created "sqlite" directory and instead create the sqlite_MSVC_Cpp_Build_Tools_Demo.bat script with the following content:

@echo off


:: ================================ BEGIN MAIN ================================
:MAIN
SetLocal EnableExtensions EnableDelayedExpansion

set ERROR_STATUS=0

set BASEDIR=%~dp0
set BASEDIR=%BASEDIR:~0,-1%
set DISTRODIR=%BASEDIR%\sqlite

call :DOWNLOAD_SQLITE
if %ERROR_STATUS% NEQ 0 exit /b 1
call :EXTRACT_SQLITE
if %ERROR_STATUS% NEQ 0 exit /b 1
if not exist "%DISTRODIR%" (
  echo Distro directory does not exists. Exiting
  exit /b 1
)
call :BUILD_SQLITE
if %ERROR_STATUS% NEQ 0 exit /b 1

EndLocal
exit /b 0
:: ================================= END MAIN =================================


:: ============================================================================
:DOWNLOAD_SQLITE
set YEAR=2024
set VERSION=3460000
set DISTROFILE=sqlite.zip
set URL=https://sqlite.org/%YEAR%/sqlite-amalgamation-%VERSION%.zip

if not exist "%DISTROFILE%" (
  echo ===== Downloading current SQLite release =====
  curl %URL% --output "%DISTROFILE%"
  if %ErrorLevel% EQU 0 (
    echo ----- Downloaded  current SQLite release -----
  ) else (
    set ERROR_STATUS=%ErrorLevel%
    echo Error downloading SQLite distro.
    echo Errod code: !ERROR_STATUS!
  )
) else (
  echo ===== Using previously downloaded SQLite distro =====
)

exit /b %ERROR_STATUS%


:: ============================================================================
:EXTRACT_SQLITE
if not exist "%DISTRODIR%\sqlite3.c" (
  echo ===== Extracting SQLite distro =====
  tar -xf "%DISTROFILE%"
  if %ErrorLevel% EQU 0 (
    move "sqlite-amalgamation-%VERSION%" "%DISTRODIR%"
    echo ----- Extracted  SQLite distro -----
  ) else (
    set ERROR_STATUS=%ErrorLevel%
    echo Error extracting SQLite distro.
    echo Errod code: !ERROR_STATUS!
  )
) else (
  echo ===== Using previously extracted SQLite distro =====
)

exit /b %ERROR_STATUS%


:: ============================================================================
:BUILD_SQLITE
cd /d "%DISTRODIR%"

if not exist sqlite3.lo     (cl -O2 -c sqlite3.c -Fosqlite3.lo)
if not exist libsqlite3.lib (lib sqlite3.lo /OUT:libsqlite3.lib)
if not exist libsqlite3.dmp (dumpbin /ALL libsqlite3.lib /OUT:libsqlite3.dmp)

echo EXPORTS > sqlite3.def
set Command=findstr /XRB /C:"^ *1 sqlite[^ ]* *$" libsqlite3.dmp
for /f "Usebackq tokens=2 delims= " %%I in (`%Command%`) do (
    echo %%I
) 1>>sqlite3.def

lib  /MACHINE:x64 /DEF:sqlite3.def
link /MACHINE:x64 /DEF:sqlite3.def sqlite3.lo /DLL /OUT:sqlite3.dll

exit /b 0

The script is relatively small and is split into functional blocks, so I will not go over it (follow the code for further details). When executed, the script downloads a copy of SQLite amalgamation release, expands it, and builds it (MSBuild environment should be activated as before). It creates the "sqlite" directory with several files, including sqlite3.dll and sqlite3.lib, which can be used as before. This process can be used to link the application dynamically against custom-built SQLite, which might integrate additional extensions, such as ICU (see, for example, this project, which focuses on the MinGW toolchain, but also discusses the MSBuild environment and provides custom build scripts).

Embedding custom SQLite - hacking into the Rusqlite build process

This part is, perhaps, the most complicated, and its primary goal is more of an exploratory nature rather than a recipe for routine use. When one of the "bundled" building options is used, the Cargo-controlled Rusqlite build process compiles the sqlite3.c amalgamation file included in the "libsqlite3-sys\sqlite3" directory of the Rusqlite repository. This amalgamation file may, in principle, be replaced with a custom copy, but that is the easy part. Because the SQLite build process is controlled during build time via compiler options, passing these options to the C compiler invoked by Cargo is essential (unless you want to deal with Rust build script ("libsqlite3-sys\build.rs"), which is beyond this exploratory). The script "libsqlite3-sys\build.rs" does accept SQLite "-Dxx" configuration parameters via the "LIBSQLITE3_FLAGS" environment variable, but it will reject other kinds of options in this variable, such as include options. Moreover, there are also linking options, which may need to be passed somehow.

For example, I have an extended script (or scripts, some available via from the associated repository and a more recent MSVC script available here), which kind of hack the SQLite build process. The scripts not only enable integrated SQLite extensions but also "integrate" several loadable extensions. Among others, I integrate the Zipfile extension, which depends on the zlib library, and enable the ICU extension, which depends on the ICU library. Both of these extensions require compiler and linker flags. I am not aware of a generic solution, but MSBuild tools support special "CL"/"_CL_" and "LINK"/"_LINK_" environment variables, which permit passing the necessary compiler/linker options. Most of the code of the extended scripts is focused on building a customized amalgamation file. Once prepared, this amalgamation can be compiled to the dll library or used to replace the amalgamation included with Rusqlite. Before calling Cargo, the script sets the mentioned environment variables. The relevant section of the script:

:: ============================================================================
:RUSQLITE
:: 
:: If RUSQLITE_REPO is set and valid, execute bundled build 
:: 

if not exist "%RUSQLITE_REPO%\libsqlite3-sys\sqlite3\sqlite3.c" (exit /b 0)


echo ========== Building RUSQLITE ===========

cd /d "%RUSQLITE_REPO%\libsqlite3-sys\sqlite3"
if not exist "sqlite3.c.orig" (
    copy /Y "sqlite3.c" "sqlite3.c.orig"
    copy /Y "sqlite3.h" "sqlite3.h.orig"
)
copy /Y "%BINDIR%\src"

if %USE_ZLIB% EQU 1 (
    set ZLIBINCDIR=!DISTRODIR!\compat\zlib
    set ZLIBLIBDIR=!DISTRODIR!\compat\zlib
    set _CL_=!_CL_! "-I%DISTRODIR%\compat\zlib"
    set LINK=!LINK! "/LIBPATH:!ZLIBLIBDIR!"
    set _LINK_=!_LINK_! zdll.lib
)

if %USE_ICU% EQU 1 (
    set _CL_=!_CL_! -DSQLITE_ENABLE_ICU=1 "-I!ICUINCDIR!"
    set LINK=!LINK! "/LIBPATH:!ICULIBDIR!"
    set _LINK_=!_LINK_! icuuc.lib icuin.lib
    set Path=!ICUBINDIR!;!Path!
)

cd /d "%RUSQLITE_REPO%"
set LIBSQLITE3_FLAGS=%EXT_FEATURE_FLAGS%
set SQLITE3_LIB_DIR=%BINDIR%"
::set LINK=!LINK! "/LIBPATH:%BINDIR%"
if not defined EXAMPLE_NAME set EXAMPLE_NAME=intro_sqlite_function_list
rem  --features bundled
call cargo build
call cargo run --example "%EXAMPLE_NAME%"
cd /d "%BASEDIR%"

echo ---------- Built    RUSQLITE -----------

exit /b 0

In addition to "-D" compiler options, for each linked library, the script passes the "INCLUDE_DIR" compiler options and "LIB_DIR" and the names of the *.lib files.

Because the SQLite library is linked statically, the most obvious way to demonstrate the difference between the regular and custom SQLite versions is to build and run a specially crafted demo. The prepared demo returns results from two queries:

SELECT name FROM pragma_module_list() ORDER BY name;
SELECT lower('щЩэЭюЮфФ') || upper('щЩэЭюЮфФ');

The first query returns the list of available modules; the second query tests case conversion with non-ANSI (in this case, Cyrillic) characters. Below is the output produced from this example compiled with and without the extras (manually aligned).

To be fair, in this particular case, this exercise was not a 100% success. It is important to remember that static linking is merely a request, which may or may not be honored. It turned out that with all the extras added, including three dynamically linked DLLs, static linking of SQLite was not possible. At the same time, this approach might still be helpful for exploratory builds of third-party applications where rusqlite feature cannot be easily specified directly.

UPDATE: Building an SQLx app

I have managed to build an SQLx app following the last approach embedding a custom SQLite amalgamation (I added a corresponding section to the extended build script mentioned above and available from GitHub). Interestingly, this time the Rust/MSBuild toolchains managed to honor the static linking request against the SQLite library. Both compiled demo project and the SQLx binary become statically linked to SQLite, while inheriting its dependencies on ICU/zlib.