Fix export command usage

[myd7349]

It seems export command gives wrong help message for specifying output directory.

C:\Users\myd7349>vcpkg export edflib --directory D:\edflib
error: unexpected switch: --directory
vcpkg export <port names> [--nuget] [--directory=out_dir]
vcpkg export zlib zlib:x64-windows boost --nuget
Options:
    ...

[myd7349]

vcpkg export <port names> [--nuget] [--output-dir=out_dir]"

vs

vcpkg export <port names> [--nuget] [--output-dir=<dir>]"

Which one do you prefer?

Should I update other l10n files in locales folder or just leave to bot?

[dg0yt]

C:\Users\myd7349>vcpkg export edflib --directory D:\edflib
error: unexpected switch: --directory
vcpkg export [--nuget] [--directory=out_dir]

Does the = make a difference?

[myd7349]

C:\Users\myd7349>vcpkg export edflib --directory D:\edflib
error: unexpected switch: --directory
vcpkg export [--nuget] [--directory=out_dir]

Does the = make a difference?

Still with no luck:

C:\Users\myd7349>vcpkg export edflib --directory=D:\abc --zip
error: unexpected option: --directory=D:\abc
vcpkg export <port names> [--nuget] [--directory=out_dir]
vcpkg export zlib zlib:x64-windows boost --nuget

--output-dir, however, works in both cases:

C:\Users\myd7349>vcpkg export edflib --output-dir D:\abc --zip
The following packages are already built and will be exported:
    edflib:x64-windows
  * vcpkg-cmake:x64-windows
  * vcpkg-cmake-config:x64-windows
Additional packages (*) need to be exported to complete this operation.
Exporting vcpkg-cmake:x64-windows...
Exporting vcpkg-cmake-config:x64-windows...
Exporting edflib:x64-windows...
Creating zip archive...
Zip archive exported at: D:\abc\vcpkg-export-20240706-195740.zip
To use exported libraries in CMake projects, add -DCMAKE_TOOLCHAIN_FILE=[...]/scripts/buildsystems/vcpkg.cmake to your CMake command line.

C:\Users\myd7349>vcpkg export edflib --output-dir=D:\abc --zip
The following packages are already built and will be exported:
    edflib:x64-windows
  * vcpkg-cmake:x64-windows
  * vcpkg-cmake-config:x64-windows
Additional packages (*) need to be exported to complete this operation.
Exporting vcpkg-cmake:x64-windows...
Exporting vcpkg-cmake-config:x64-windows...
Exporting edflib:x64-windows...
Creating zip archive...
Zip archive exported at: D:\abc\vcpkg-export-20240706-195751.zip
To use exported libraries in CMake projects, add -DCMAKE_TOOLCHAIN_FILE=[...]/scripts/buildsystems/vcpkg.cmake to your CMake command line.

[myd7349]

vcpkg-tool/src/vcpkg/commands.export.cpp

Line 330 in 9eb99f7

auto output_dir_opt = Util::lookup_value(options.settings, SwitchOutputDir);

and

vcpkg-tool/src/vcpkg/commands.export.cpp

Line 354 in 9eb99f7

ret.output_dir = ret.output_dir.empty() ? Util::lookup_value(options.settings, SwitchOutputDir)

both references SwitchOutputDir, which is defined here:

vcpkg-tool/include/vcpkg/base/contractual-constants.h

Line 251 in 9eb99f7

inline constexpr StringLiteral SwitchOutputDir = "output-dir";

[BillyONeal]

Thanks for the fix!