cmake: add CURL_BUILD_EVERYTHING option

To build all targets in a single go, meaning curl and libcurl as normal,
and tests and examples in addition. To build-test everything without
running multiple cmake commands.

Enable with:
- `-DCURL_BUILD_EVERYTHING=ON`
  Special values: `QUICK` to build examples quickly for build test,
  `NOEXAMPLES` to not build examples.

A well-equipped build takes 2.8s of configure time, and 1.7s to build
everything (shared, unity, ninja, prefill), 1.4s with `QUICK`. Without
this option it takes <1s to build curl/libcurl.

Also: streamline `CURL_LINT` internal logic.

Closes #20429

CMakeLists.txt

@@ -178,6 +178,7 @@ option(BUILD_STATIC_LIBS "Build static libraries" OFF)
 option(BUILD_STATIC_CURL "Build curl executable with static libcurl" OFF)
 option(ENABLE_ARES "Enable c-ares support" OFF)
 option(CURL_DISABLE_INSTALL "Disable installation targets" OFF)
+option(CURL_BUILD_EVERYTHING "Build optional build targets (examples, tests) by default" OFF)
 
 if(WIN32)
   option(ENABLE_UNICODE "Use the Unicode version of the Windows API functions" OFF)
@@ -545,10 +546,7 @@ if(PERL_EXECUTABLE)
     COMMAND "${PERL_EXECUTABLE}" "${PROJECT_SOURCE_DIR}/scripts/firefox-db2pem.sh" "lib/ca-bundle.crt"
     DEPENDS "${PROJECT_SOURCE_DIR}/scripts/firefox-db2pem.sh"
   )
-  if(CURL_LINT)
-    set(_lint_all ALL)
-  endif()
-  add_custom_target(curl-lint "${_lint_all}"
+  add_custom_target(curl-lint
     COMMENT "Running lint checks" VERBATIM USES_TERMINAL
     WORKING_DIRECTORY ${PROJECT_SOURCE_DIR}
     COMMAND "${PERL_EXECUTABLE}" "${PROJECT_SOURCE_DIR}/scripts/checksrc-all.pl"
@@ -557,6 +555,9 @@ if(PERL_EXECUTABLE)
       "${PROJECT_SOURCE_DIR}/scripts/checksrc-all.pl" "${PROJECT_SOURCE_DIR}/scripts/checksrc.pl"
       "${PROJECT_SOURCE_DIR}/scripts/spacecheck.pl"
   )
+  if(CURL_LINT)
+    set_target_properties(curl-lint PROPERTIES EXCLUDE_FROM_ALL FALSE)
+  endif()
 endif()
 
 option(BUILD_LIBCURL_DOCS "Build libcurl man pages" ON)

docs/INSTALL-CMAKE.md

@@ -225,6 +225,9 @@ target_link_libraries(my_target PRIVATE CURL::libcurl)
 - `BUILD_STATIC_CURL`:                      Build curl executable with static libcurl. Default: `OFF` (turns to `ON`, when building static libcurl only)
 - `BUILD_STATIC_LIBS`:                      Build static libraries. Default: `OFF` (turns to `ON` if `BUILD_SHARED_LIBS` is `OFF`)
 - `BUILD_TESTING`:                          Build tests. Default: `ON`
+- `CURL_BUILD_EVERYTHING`:                  Build optional build targets (examples, tests) by default. Default: `OFF`
+                                            Set `QUICK` to build examples quickly with the `curl-examples-build` target (for build tests).
+                                            Set `NOEXAMPLES` to not build examples.
 - `CURL_CLANG_TIDY`:                        Run the build through `clang-tidy`. Default: `OFF`
                                             If enabled, it implies `CMAKE_UNITY_BUILD=OFF` and `CURL_DISABLE_TYPECHECK=ON`.
 - `CURL_CLANG_TIDYFLAGS`:                   Custom options to pass to `clang-tidy`. Default: (empty)

docs/examples/CMakeLists.txt

@@ -21,7 +21,6 @@
 # SPDX-License-Identifier: curl
 #
 ###########################################################################
-
 add_custom_target(curl-examples)
 
 # Get check_PROGRAMS, COMPLICATED_MAY_BUILD, COMPLICATED_EXAMPLES variables
@@ -90,3 +89,9 @@ endforeach()
 if(_with_deps)
   message(STATUS "Enabled examples with dependencies:${_with_deps}")
 endif()
+
+if(CURL_BUILD_EVERYTHING STREQUAL "QUICK")
+  set_target_properties(curl-examples-build PROPERTIES EXCLUDE_FROM_ALL FALSE)
+elseif(CURL_BUILD_EVERYTHING AND NOT CURL_BUILD_EVERYTHING STREQUAL "NOEXAMPLES")
+  set_target_properties(curl-examples PROPERTIES EXCLUDE_FROM_ALL FALSE)
+endif()

tests/CMakeLists.txt

@@ -33,6 +33,9 @@ add_custom_target(testdeps)
 if(BUILD_CURL_EXE)
   add_dependencies(testdeps "curlinfo")
 endif()
+if(CURL_BUILD_EVERYTHING)
+  set_target_properties(testdeps PROPERTIES EXCLUDE_FROM_ALL FALSE)
+endif()
 
 if(CURL_CLANG_TIDY)
   add_custom_target(tests-clang-tidy)