build: omit certain deps from `libcurl.pc` unless found via `pkg-config`

The idea of linking dependencies found to `libcurl.pc` turns out not
to work in practice in some cases.

build: omit certain deps from `libcurl.pc` unless found via `pkg-config`

The idea of linking dependencies found to `libcurl.pc` turns out not
to work in practice in some cases.

Specifically: gss, ldap, mbedtls, libmsh3, rustls

A `.pc` may not work or be missing for a couple of reasons:
- not all build methods generate it: mbedTLS, Rustls
- generated file is broken: msh3
Ref: https://github.com/nibanks/msh3/pull/225
- installed package flavour isn't shipping with one:
FreeBSD GSS, OmniOS LDAP, macOS LDAP

The effect of such issues shall be subtle in theory, because
`libcurl.pc` normally lists these dependencies in the `Requires.private`
section meant for static linking. But, e.g. `pkg-config --exists`
requires these to be present, and builds sometimes use this check
regardless of build type. This bug is not present in `pkgconf`; it only
checks for them when `--static` is also passed.

Fix these by adding affected `.pc` references to `libcurl.pc` only when
we detected the dependency via `pkg-config`.

There are a few side-effects of this solution:
- references are never added for dependencies where curl doesn't
implement `pkg-config` detection. These are:
- autotools: ldap, mbedtls, msh3
- cmake: ldap (pending #15273)
- generated `libcurl.pc` depends on the build-time environment.
- generated `libcurl.pc` depends on curl build tool (cmake, autotools).
- generated `libcurl.pc` depends on curl build implementation details.

Make an exception for GNU GSS, where I blindly guess that `gss.pc` is
always available, as no issues were reported.

Other, not mentioned, dependencies continue to be added regardless
of the detection method.

Reported-by: Harmen Stoppels, Thomas, Daniel Engberg, Andy Fiddaman
Fixes #15469
Fixes #15507
Fixes #15535
Fixes https://github.com/curl/curl/pull/15163#issuecomment-2473358444
Closes #15573

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cmake: sync GSS config code with other deps

- stop passing explicit libpaths via `CMAKE_SHARED_LINKER_FLAGS` and
`CMAKE_EXE_LINKER_FLAGS`. `link_directories()` is doing that already.

cmake: sync GSS config code with other deps

- stop passing explicit libpaths via `CMAKE_SHARED_LINKER_FLAGS` and
`CMAKE_EXE_LINKER_FLAGS`. `link_directories()` is doing that already.
- use `curl_required_libpaths()` to pass libpaths to the feature test.
Reported-by: Daniel Engberg
Fixes #15536
Also fixes GSS feature detection with non-gcc/clang compilers,
such as MSVC.
- add libpaths to `CURL_LIBPATHS`.
- move `GSS_CFLAGS`, `GSS_LDFLAGS` stringifications to FindGSS.
To match the `CFLAGS` format returned by the rest of Find modules.
- reorder calls to match other dependencies.
- don't extend system `LDFLAGS` when FindGSS did not return any.
- ignore `LDFLAGS` when detecting GSS via `pkg-config`. `LDFLAGS` holds
a copy of libpaths and libs in this case. Ignore those to avoid these
duplicates making into `libcurl.pc` and `curl-config`. Also syncing
behavior with other Find modules which also ignore raw `LDFLAGS`.
- ignore raw `LDFLAGS` coming from `krb5-config --libs`. FindGSS
no longer returns dependency-specific `LDFLAGS` after this. Syncing
behavior with other Find modules.
- reduce scope of checker state push/pop/set.

Closes #15545

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cmake: document `-D` and env build options

Extend `INSTALL-CMAKE` document with the list of available options,
a short description and default values.

The list may not be 100% c

cmake: document `-D` and env build options

Extend `INSTALL-CMAKE` document with the list of available options,
a short description and default values.

The list may not be 100% complete.

There are no component boundaries in CMake, so the line is blurry
between curl options, CMake options, CMake Find modules options.
I included certain CMake options that seemed useful, and/or have
dedicated use withing curl's CMake source. But, all CMake built-in
options are usable, as documented upstream in CMake.

The naming of the options has a heritage and the inconsistencies with
it, including a lack of clear namespace. This may be subject to future
updates, also after figuring out which name has special meaning within
CMake and/or CMake projects out of unwritten convention or something
more tangible.

CMake allows to initialize any internal variable via `-D`. This may be
useful to pre-initialize/override feature check results. The list
doesn't contain these, and they remain officially undocumented.

Also:
- make adjustments to keep the spellchecker happy.
- retrofit description changes to the cmake sources.
- stop documenting deprecated `Find*` variables.

Reported-by: Daniel Stenberg
Fixes https://github.com/curl/curl/discussions/14885
Closes #15388

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cmake: use `cmake_push_check_state()` around feature checks

Enclose
`CMAKE_EXTRA_INCLUDE_FILES`,
`CMAKE_REQUIRED_DEFINITIONS`,
`CMAKE_REQUIRED_FLAGS`,
`CMAKE_REQUIRED_INCLUDE

cmake: use `cmake_push_check_state()` around feature checks

Enclose
`CMAKE_EXTRA_INCLUDE_FILES`,
`CMAKE_REQUIRED_DEFINITIONS`,
`CMAKE_REQUIRED_FLAGS`,
`CMAKE_REQUIRED_INCLUDES`,
`CMAKE_REQUIRED_LIBRARIES`,
`CMAKE_REQUIRED_LINK_OPTIONS`,
settings within `cmake_push_check_state()`/`cmake_pop_check_state()`
calls. It prevents spilling them into other feature checks. It also
replaces manual resets found in some places (which can have
the undesired side-effect of destroying values meant for global use.)

Cherry-picked from #15157
Closes #15251

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cmake: detect GNU GSS

Fix to set `HAVE_GSSGNU` when GNU GSS is detected.

Also set the appropriate `pkg-config` dependency and do version
detection for the GNU GSS flavour.

cmake: detect GNU GSS

Fix to set `HAVE_GSSGNU` when GNU GSS is detected.

Also set the appropriate `pkg-config` dependency and do version
detection for the GNU GSS flavour.

Tested with `pkg-config` and partly tested without. The latter case
picks up everything else but, in my env. This is likely not the last
word to implement this detection correctly for all build-cases.

GNU GSS doesn't seem to have a Homebrew formula and building
it locally needs manual tweaks to make finish successfully.

Also move a MIT-specific header detection into to MIT-specific `if`
branch.

Closes #15176

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cmake: minor tidy-ups

- show `OpenSSL v3+` when detected (as in `./configure`).
(this string also makes its way to `curl-config`.)
- prefer `unset(VAR)` over `set(VAR)`.
Same

cmake: minor tidy-ups

- show `OpenSSL v3+` when detected (as in `./configure`).
(this string also makes its way to `curl-config`.)
- prefer `unset(VAR)` over `set(VAR)`.
Same effect, but `unset()` tells the intent unambiguously.
https://cmake.org/cmake/help/latest/command/set.html
- drop "implementation" from an `option()` description.
- FindGSS: replace legacy keyword alias with modern alternative.
https://cmake.org/cmake/help/latest/command/get_filename_component.html
- move `CURL_STATIC_CRT` logic next to its `option()`.
- improve order of `libcurl.pc`/`curl-config` variable init lines.
- tests: drop/shorten custom target names.
They inflated generated make files by 550KB.
Keep target name logic for sync between code snippets.
Follow-up to a2ef5d36b3cdec8120a4a9b782d18d58a70d4236 #14660
- clear a variable after use.
- restore `STATUS` for `Features:`/`Protocols:` `message()`s:
Without it the output goes to stderr, and appears in red in CMake GUI.
It doesn't seem possible to show a line on stdout without leading
underscores to match `curl -V` and `./configure` output.
Partial revert of acbc6b703f6b0ee568d053f6f2565fbc107b5fd3 #14197
- WindowsCache: move `HAVE_LINUX_TCP_H` into the header group.
- move strings to the same line as their `STRING` keyword.
- formatting in generated code.
- delete bogus comment.
- unfold lines for readability.
- fix a too long line. (for cmakelint)
- missing quotes, whitespace, comments.

Closes #14610

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cmake/FindGSS: bring closer to other Find modules

- add pkg-config-specific 'Found' message to the Find module.

- update non-pkg-config 'Found' message to show the flavour instead o

cmake/FindGSS: bring closer to other Find modules

- add pkg-config-specific 'Found' message to the Find module.

- update non-pkg-config 'Found' message to show the flavour instead of
the library name. (= the first value listed after `REQUIRED_VARS`)

- delete extra 'Found' message from `CMakeLists.txt`.

- rename internal result variables to match with default pkg-config
names, in preparation of introducing them in other Find modules:
- `GSS_LINK_DIRECTORIES` -> `GSS_LIBRARY_DIRS`
- `GSS_LINKER_FLAGS` -> `GSS_LDFLAGS`
- `GSS_COMPILER_FLAGS` -> `GSS_CFLAGS`

Ref: #14652

Closes #14651

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cmake: fix `cmakelint` warnings

- keep line lengths below 132 characters.
- fix two "weird indentation" warnings.

Reported-by: Dan Fandrich
Bug: #14580

Closes #14583

cmake: tidy up more in Find modules

- add `NAMES` where missing.
- document input variables (including deprecated ones.)
- comment cleanups.
- FindWolfSSL: drop stray `QUIET` fro

cmake: tidy up more in Find modules

- add `NAMES` where missing.
- document input variables (including deprecated ones.)
- comment cleanups.
- FindWolfSSL: drop stray `QUIET` from `pkg_check_modules()`.
(`QUIET` may be re-added for all modules in the future.)

Closes #14579

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cmake: tidy-up continues

- move variable dump to a GHA foldable group.
- minimize scope for an include().
- rename `HIDES_CURL_PRIVATE_SYMBOLS` to `CURL_HIDES_PRIVATE_SYMBOLS`,

cmake: tidy-up continues

- move variable dump to a GHA foldable group.
- minimize scope for an include().
- rename `HIDES_CURL_PRIVATE_SYMBOLS` to `CURL_HIDES_PRIVATE_SYMBOLS`,
to keep it in the curl namespace.
- drop quotes from a version number.
- add missing `Makefile.inc` var refs to comment.
- FindNGTCP2: rename internal var to underscore/lowercase.
- FindBearSSL, FindGSS: whitespace.

Closes #14571

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cmake: sync up result variable names in Find modules

- bearssl, c-ares, gss, libpsl, libssh2, mbedtls:
Before this patch these Find modules returned results via
`<NAME>_INCLUDE_D

cmake: sync up result variable names in Find modules

- bearssl, c-ares, gss, libpsl, libssh2, mbedtls:
Before this patch these Find modules returned results via
`<NAME>_INCLUDE_DIR` and `<NAME>_LIBRARY`.

This patch makes them return `<NAME>_INCLUDE_DIRS` (note the `S`)
and `<NAME>_LIBRARIES` like other modules already did.

- bearssl, mbedtls:
Before this patch these Find modules allowed custom configuration
via `<NAME>_INCLUDE_DIRS` (note the `S`).

This patch makes them accept `<NAME>_INCLUDE_DIR`, like the rest of
the modules did.

Deprecate the old variables, but keep accepting them for
compatibility.

- bearssl: add missing `mark_as_advanced()` call.

Closes #14542

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cmake: tidy up Find modules

Smoothen out minor differences between Find modules.

- brotli, nghttp2: drop redundant `FOUND_VAR` specifiers from
`find_package_handle_standard_ar

cmake: tidy up Find modules

Smoothen out minor differences between Find modules.

- brotli, nghttp2: drop redundant `FOUND_VAR` specifiers from
`find_package_handle_standard_args()` calls.
This function sets both `<NAME_UPPER>_FOUND` and `<NAME>_FOUND`
by default.

- brotli: set result vars only when found.

- brotli: add missing `mark_as_advanced()` call.

- brotli: delete custom fail message.

- mbedtls, bearssl: use `REQUIRED_VARS` instead of `DEFAULT_MSG`.

- msh3, quiche: set `<NAME>_VERSION` (via pkg-config).

- wolfssl: also use `PC_WOLFSSL_INCLUDEDIR`, `PC_WOLFSSL_LIBDIR`
as hints.

- libpsl, libssh2, zstd: clear temporary variables used for version
detection.

- gss, msh3, nghttp2, nghttp3, ngtcp2, quiche, zstd: fix to apply
`mark_as_advanced()` to internal variables only.

Closes #14538

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cmake: sync up formatting in Find modules

- lowercase internal variable names (FindGSS)
- comments
- whitespace

Closes #14527

cmake: add `CURL_USE_PKGCONFIG` option

Add option to control whether to use `pkg-config` to detect
dependencies. Curl's CMake uses `pkg-config` by default for all targets
except for

cmake: add `CURL_USE_PKGCONFIG` option

Add option to control whether to use `pkg-config` to detect
dependencies. Curl's CMake uses `pkg-config` by default for all targets
except for MSVC without vcpkg.

With the CMake option `-DCURL_USE_PKGCONFIG=ON` you can override it to
use `pkg-config` always.

If `pkg-config` is causing issues, e.g. in cross-builds or other cases,
`-DCURL_USE_PKGCONFIG=OFF` disables all use of `pkg-config`.

Also add it to `curl-config.cmake`. Not yet used, but will be once curl
starts referencing any curl-specific `Find*` module from this public
script.

Follow-up to 9dfdc6ff42ba045ec48056bb6d2072f2fcac2e9d #14483
Closes #14504

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cmake: allow `pkg-config` in more envs

Before this patch, `pkg-config` was used for `UNIX` builds only (with
a few exceptions like wolfSSL, libssh, gsasl, libuv). This patch extends

cmake: allow `pkg-config` in more envs

Before this patch, `pkg-config` was used for `UNIX` builds only (with
a few exceptions like wolfSSL, libssh, gsasl, libuv). This patch extends
`pkg-config` use to all envs except: `MSVC` without vcpkg. Meaning MSVC
with vcpkg will now use it. Also mingw on Windows.

Also apply the new condition to options where `pkg-config` was used
unconditionally (= for all targets). These are:
`-DCURL_USE_WOLFSSL=ON`, `-DCURL_USE_LIBSSH=ON`,
`-DCURL_USE_GSASL=ON` and `-DCURL_USE_LIBUV=ON`

This patch may still cause regressions for cross-builds (e.g. mingw
cross-build from Unix) and potentially other cases. If that happens, we
recommend using some of these methods to explicitly disable `pkg-config`
when using CMake:
- CMake option: `-DPKG_CONFIG_EXECUTABLE=`
(or `-DPKG_CONFIG_EXECUTABLE=nonexistent` or similar)
This is similar to the (curl-specific) `PKG_CONFIG` env for autotools.
- export env: `PKG_CONFIG_LIBDIR=`
(or `PKG_CONFIG_PATH`, `PKG_CONFIG_SYSROOT_DIR`,
or the CMake-specific `PKG_CONFIG`)

We may improve control over this in a future patch, also allowing opting
in MSVC (without vcpkg).

Ref: #14405
Ref: #14408
Ref: #14140
Closes #14483

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cmake: fix version variable references in FindGSS

Assign the value of the variable instead of the name of the variable
when detecting GSS version via `pkg-config` on old (?) CMake.

cmake: fix version variable references in FindGSS

Assign the value of the variable instead of the name of the variable
when detecting GSS version via `pkg-config` on old (?) CMake.

(On recent CMake, there is an empty value in these variables.)

Closes #14445

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cmake: more syntax tidy-up

- quote string literals.
In the hope it improves syntax-highlighting and readability.

- use lowercase, underscore-prefixed local var names.
As

cmake: more syntax tidy-up

- quote string literals.
In the hope it improves syntax-highlighting and readability.

- use lowercase, underscore-prefixed local var names.
As a hint for scope, to help readability.

- prefer `pkg_search_module` (over `pkg_check_modules`).
They are the same, but `pkg_search_module` stops searching
at the first hit.

- more `IN LISTS` in `foreach()`.

- OtherTests.cmake: clear `CMAKE_EXTRA_INCLUDE_FILES` after use.

- add `PROJECT_LABEL` for http/client and unit test targets.

- sync `Find*` module comments and formatting.

- drop a few local variables.

- drop bogus `CARES_LIBRARIES` from comment.

- unquote numeric literal.

Follow-up to acbc6b703f6b0ee568d053f6f2565fbc107b5fd3 #14197
Closes #14388

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cmake: fix `pkg-config`-based detection in `FindGSS.cmake`

Before this patch `pkg-config`-based detection was ignored, and used
solely as a path hint for native detection.

- fix

cmake: fix `pkg-config`-based detection in `FindGSS.cmake`

Before this patch `pkg-config`-based detection was ignored, and used
solely as a path hint for native detection.

- fix `pkg_search_module()` result prefix to match what code expects:
`_GSS` (was: `_GSS_PKG`). Update variable that were in sync with old
prefix.

- update the pkg-config codepath to use `_GSS_MODULE_NAME` to detect
GSS flavour. This requires CMake 3.16.
Otherwise fall back to the old method. (The old method doesn't seem to
work anymore (?) as of CMake 3.30.1. Documented
`<prefix>_<modulename>_VERSION` variable is defined, but empty.)

- update the pkg-config codepath to use `_GSS_VERSION` set by CMake.
Resort to the old code when this variable is empty. (The old code
doesn't seem to work anymore (?) as of CMake 3.30.1)

- fix pkg-config codepath to set the documented result variables.

- align native detection variable names with those generated by
`pkg_search_module()` in the pkg-config codepath.

- GHA/macos: enable GSS Heimdal in a cmake job.
Uses the native detection.

- GHA/linux: enable GSS Heimdal in cmake and autotools jobs.
CMake uses `pkg-config`-based detection.

- suppress test 2077 and 2078 results on Linux + Heimdal.
```
FAIL-IGNORED 2077: 'curl --fail --negotiate to unauthenticated service fails' HTTP, HTTP GET, GSS-API
FAIL-IGNORED 2078: 'curl --negotiate should not send empty POST request only' HTTP, HTTP GET, GSS-API
```
Failing with valgrind errors in both autotools and cmake builds:
https://github.com/curl/curl/actions/runs/10282222581/job/28453472068?pr=14430#step:38:3638
https://github.com/curl/curl/actions/runs/10282222581/job/28453473398?pr=14430#step:38:7831

Closes #14430

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cmake: fix `GSS_VERSION` for Heimdal found via pkg-config

Previously used source variable was never defined, possibly due
to a copy-paste-edit typo.

Closes #14393

cmake: tidy-ups

- tidy-up comments.
- use lowercase, underscore prefixed names for internal variables.
- use `IN LISTS` and `IN ITEMS` in `foreach()` loops.
- rename variable nam

cmake: tidy-ups

- tidy-up comments.
- use lowercase, underscore prefixed names for internal variables.
- use `IN LISTS` and `IN ITEMS` in `foreach()` loops.
- rename variable name `OUTPUT` to a more distinctive one.
- tidy-up `STREQUAL` syntax.
- delete commented code.
- indent/whitespace.

Closes #14197

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cmake: whitespace, formatting/tidy-up in comments

Also correct casing in a few option descriptions.

Closes #13711

cmake: use list APPEND syntax for CMAKE_REQUIRED_DEFINITIONS

- Use list() instead of set() for CMAKE_REQUIRED_DEFINITIONS list since
the former is clearer.

Closes https://gith

cmake: use list APPEND syntax for CMAKE_REQUIRED_DEFINITIONS

- Use list() instead of set() for CMAKE_REQUIRED_DEFINITIONS list since
the former is clearer.

Closes https://github.com/curl/curl/pull/10272

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copyright: update all copyright lines and remove year ranges

- they are mostly pointless in all major jurisdictions
- many big corporations and projects already don't use them
- save

copyright: update all copyright lines and remove year ranges

- they are mostly pointless in all major jurisdictions
- many big corporations and projects already don't use them
- saves us from pointless churn
- git keeps history for us
- the year range is kept in COPYING

checksrc is updated to allow non-year using copyright statements

Closes #10205

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copyright: make repository REUSE compliant

Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the

copyright: make repository REUSE compliant

Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.

This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.

Closes #8869

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curl.se: new home

Closes #6172