Merge bitcoin/bitcoin#24470: Disallow more unsafe string->path conversions allowed by path append operators

f64aa9c411ad78259756a28756ec1eb8069b5ab4 Disallow more unsafe string->path conversions allowed by path append operators (Ryan Ofsky)

Pull request description:

  Add more `fs::path` `operator/` and `operator+` overloads to prevent unsafe string->path conversions on Windows that would cause strings to be decoded according to the current Windows locale & code page instead of the correct string encoding.

  Update application code to deal with loss of implicit string->path conversions by calling `fs::u8path` or `fs::PathFromString` explicitly, or by just changing variable types from `std::string` to `fs::path` to avoid conversions altogether, or make them happen earlier.

  In all cases, there's no change in behavior either (1) because strings only contained ASCII characters and would be decoded the same regardless of what encoding was used, or (2) because of the 1:1 mapping between paths and strings using the `PathToString` and `PathFromString` functions.

  Motivation for this PR was just that I was experimenting with #24469 and noticed that operations like `fs::path / std::string` were allowed, and I thought it would be better not to allow them.

ACKs for top commit:
  hebasto:
    ACK f64aa9c411ad78259756a28756ec1eb8069b5ab4

Tree-SHA512: 944cce49ed51537ee7a35ea4ea7f5feaf0c8fff2fa67ee81ec5adebfd3dcbaf41b73eb35e49973d5f852620367f13506fd12a7a9b5ae3a7a0007414d5c9df50f

1 files changed, 3 insertions, 3 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 1ca20fd848..b880a7a9fd 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -2049,7 +2049,7 @@ BOOST_AUTO_TEST_CASE(test_ParseFixedPoint)
     BOOST_CHECK(!ParseFixedPoint("31.999999999999999999999", 3, &amount));
 }
 
-static void TestOtherThread(fs::path dirname, std::string lockname, bool *result)
+static void TestOtherThread(fs::path dirname, fs::path lockname, bool *result)
 {
     *result = LockDirectory(dirname, lockname);
 }
@@ -2059,7 +2059,7 @@ static constexpr char LockCommand = 'L';
 static constexpr char UnlockCommand = 'U';
 static constexpr char ExitCommand = 'X';
 
-[[noreturn]] static void TestOtherProcess(fs::path dirname, std::string lockname, int fd)
+[[noreturn]] static void TestOtherProcess(fs::path dirname, fs::path lockname, int fd)
 {
     char ch;
     while (true) {
@@ -2090,7 +2090,7 @@ static constexpr char ExitCommand = 'X';
 BOOST_AUTO_TEST_CASE(test_LockDirectory)
 {
     fs::path dirname = m_args.GetDataDirBase() / "lock_dir";
-    const std::string lockname = ".lock";
+    const fs::path lockname = ".lock";
 #ifndef WIN32
     // Revert SIGCHLD to default, otherwise boost.test will catch and fail on
     // it: there is BOOST_TEST_IGNORE_SIGCHLD but that only works when defined