Repository: bitcoin
Issue: Bitcoin ignores datadir and blocksdir parameter in .conf
Labels: GUI,Utils/log/libs

### Is there an existing issue for this?

- [ ] Similar questions was raised in #15745 but it is marked as "solved" and closed.

### Current behaviour

Registry has a REG_SZ key `HKEY_CURRENT_USER\SOFTWARE\Bitcoin\Bitcoin-Qt\strDataDir` (and there can be Bitcoin-Qt-regtest\strDataDir, Bitcoin-Qt-testnet\strDataDir for test chains).
It is created by default when bitcoin-qt starts first time and after editing/accepting first start wizard.
Change database directory to non-default path, put there bitcoin.conf with datadir=databasepath and run bitcoin-qt (-cli/etc) and bitcoin ignores datadir path if no -datadir argument passed to a program exclusively.
**The same problem with the blocksdir parameter.**

### Expected behaviour

In all situations behavior must be identical - if we start without arguments or pass "-conf" then use .conf "datadir=path" (according to sections [main], [regtest], [test] or global if there are no sections) if .conf exists and datadir are there. Now it is ignored.
If we start with "-datadir=path" argument it's works.

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### Steps to reproduce

1. For example, change `HKEY_CURRENT_USER\SOFTWARE\Bitcoin\Bitcoin-Qt\strDataDir` to `W:\BitcoinCore\strDataDir` (assuming our disk is W: and all paths in this example exists).
2. Create W:\BitcoinCore\strDataDir\bitcoin.conf with three lines:
`datadir=W:/BitcoinCore/DataDir/main1
[main]
datadir=W:/BitcoinCore/DataDir/main2`
3. Start `bitcoin-qt.exe -debuglogfile=W:/BitcoinCore/debug.no_params.log`
4. After a few seconds close opened wallet (bitcoin-qt) [Alt-F4].
5. Start `bitcoin-qt.exe -datadir=W:\BitcoinCore\DataDir\main -debuglogfile=W:\BitcoinCore\debug.w_datadir_param.log`   
6. After a few seconds close opened wallet (bitcoin-qt) [Alt-F4].
7. Start `bitcoin-qt.exe -conf=W:\BitcoinCore\strDataDir\bitcoin.conf -debuglogfile=W:\BitcoinCore\debug.w_conf_param.log`   
8. After a few seconds close opened wallet (bitcoin-qt) [Alt-F4].
9. Check filesystem and logs (attached).

I've used Sysinternals Process Monitor to dig what's happening.

- - -
### Relevant log output

**debug.no_params.log**:

> Default data directory C:\Users\USERNAME\AppData\Roaming\Bitcoin
> **Using data directory** W:\BitcoinCore\\**strDataDir**
> Config file: W:\BitcoinCore\strDataDir\bitcoin.conf
> Config file arg: datadir="W:/BitcoinCore/DataDir/main1"
> **Config file arg**: **[main] datadir**="W:/BitcoinCore/**DataDir/main2**"
> Creating peers.dat because the file was not found ("W:\BitcoinCore\\**strDataDir**\peers.dat")
> Opening LevelDB in W:\BitcoinCore\\**strDataDir\blocks\index**
> Opening LevelDB in W:\BitcoinCore\\**strDataDir\chainstate**

**debug.w_datadir_param.log**:

> Default data directory C:\Users\USERNAME\AppData\Roaming\Bitcoin
> **Using data directory** W:\BitcoinCore\\**DataDir\main**
> Config file: W:\BitcoinCore\DataDir\main\bitcoin.conf (not found, skipping)
> **Command-line arg**: datadir="W:\\\\BitcoinCore\\\\**DataDir\\\\main**"
> Opening LevelDB in W:\BitcoinCore\\\\**DataDir\main\blocks\index**
> Opening LevelDB in W:\BitcoinCore\\**DataDir\main\chainstate**

**debug.w_conf_param.log** output is identical to debug.no_params.log.

- - -
### How did you obtain Bitcoin Core

1. Downloaded from [bitcoincore.org/bin](https://bitcoincore.org/bin/)
2. Compiled from source

### What version of Bitcoin Core are you using?

24.0.1

### Operating system and version

Win 10 x64

### Machine specifications

Non relevant