Download re2c and Bison with FetchContent

This uses FetchContent and ExternalProject modules together.

FetchContent integrates better with find_package() calls, and
ExternalProject takes care of isolation.

Changes and notes:
- Redundant local FindBISON overrided module removed and configuration
  moved to Bison module itself.
- The SOURCE_SUBDIR option pointing to non-existing relative path
  ensures that package is not added via add_subdirectory() to not mess
  the cache variables, and package can be still downloaded via
  FetchContent_MakeAvailable() command.

Author: petk

cmake/cmake/modules/FindBISON.cmake

@@ -145,7 +145,7 @@ php_bison(foo foo.y foo.c OPTIONS -Wall --debug)
 #   bison -Wall --debug foo.y --output foo.c
 ```
 
-### Specifying options
+### Example: Specifying options
 
 This module provides some default options when using the `ADD_DEFAULT_OPTIONS`:
 
@@ -317,6 +317,12 @@ function(php_bison name input output)
     AND NOT _PHP_BISON_DOWNLOAD
   )
     find_package(BISON ${PHP_BISON_VERSION} ${quiet})
+    set_package_properties(
+      BISON
+      PROPERTIES
+        URL "https://www.gnu.org/software/bison/"
+        DESCRIPTION "General-purpose parser generator"
+    )
   endif()
 
   get_property(role GLOBAL PROPERTY CMAKE_ROLE)
@@ -655,8 +661,8 @@ function(_php_bison_download)
   )
 
   # Target created by ExternalProject:
-  if(TARGET bison)
-    add_dependencies(Bison::Bison bison)
+  if(TARGET BISON-install)
+    add_dependencies(Bison::Bison BISON-install)
   endif()
 
   # Move dependency to PACKAGES_FOUND.
@@ -676,22 +682,38 @@ function(_php_bison_download)
     _PHP_BISON_DOWNLOAD
     TRUE
     CACHE INTERNAL
-    "Internal marker whether the Bison will be downloaded."
+    "Internal marker whether Bison is downloaded."
   )
 
   return(PROPAGATE BISON_FOUND BISON_VERSION)
 endfunction()
 
 # Downloads GNU Bison.
 function(_php_bison_download_gnu)
-  message(STATUS "GNU Bison ${BISON_VERSION} will be downloaded at build phase")
+  message(
+    STATUS
+    "Downloading GNU Bison ${BISON_VERSION} from https://ftp.gnu.org/gnu/bison"
+  )
 
   include(ExternalProject)
+  include(FetchContent)
 
-  ExternalProject_Add(
-    bison
+  FetchContent_Declare(
+    BISON
     URL https://ftp.gnu.org/gnu/bison/bison-${BISON_VERSION}.tar.gz
+    SOURCE_SUBDIR non-existing
     DOWNLOAD_EXTRACT_TIMESTAMP TRUE
+    OVERRIDE_FIND_PACKAGE
+  )
+
+  FetchContent_MakeAvailable(BISON)
+
+  ExternalProject_Add(
+    BISON
+    STEP_TARGETS build install
+    SOURCE_DIR ${bison_SOURCE_DIR}
+    BINARY_DIR ${bison_BINARY_DIR}
+    INSTALL_DIR ${FETCHCONTENT_BASE_DIR}/bison-install
     CONFIGURE_COMMAND
       <SOURCE_DIR>/configure
       --disable-dependency-tracking
@@ -701,16 +723,18 @@ function(_php_bison_download_gnu)
     LOG_INSTALL TRUE
   )
 
-  ExternalProject_Get_Property(bison INSTALL_DIR)
+  ExternalProject_Get_Property(BISON INSTALL_DIR)
 
   set_property(CACHE BISON_EXECUTABLE PROPERTY VALUE ${INSTALL_DIR}/bin/bison)
 endfunction()
 
-# Downloads https://github.com/lexxmark/winflexbison.
+# Downloads winflexbison.
 function(_php_bison_download_windows)
   message(
     STATUS
-    "Downloading win_bison ${BISON_VERSION} (${PHP_BISON_WIN_VERSION_DOWNLOAD})"
+    "Downloading win_bison ${BISON_VERSION} from "
+    "https://github.com/lexxmark/winflexbison "
+    "(${PHP_BISON_WIN_VERSION_DOWNLOAD})"
   )
 
   get_directory_property(dir EP_BASE)

cmake/cmake/modules/PHP/Bison.cmake

@@ -618,60 +618,73 @@ function(_php_re2c_download)
     )
   endif()
 
-  message(STATUS "Re2c ${RE2C_VERSION} will be downloaded at build phase")
+  message(
+    STATUS
+    "Downloading re2c ${RE2C_VERSION} from https://github.com/skvadrik/re2c"
+  )
 
   include(ExternalProject)
+  include(FetchContent)
+
+  FetchContent_Declare(
+    RE2C
+    URL https://github.com/skvadrik/re2c/archive/refs/tags/${RE2C_VERSION}.tar.gz
+    SOURCE_SUBDIR non-existing
+    OVERRIDE_FIND_PACKAGE
+  )
+
+  FetchContent_MakeAvailable(RE2C)
 
   # Configure re2c build.
+  set(options -DRE2C_BUILD_RE2GO=OFF -DRE2C_BUILD_RE2RUST=OFF)
+
   if(RE2C_VERSION VERSION_GREATER_EQUAL 4)
-    set(
-      re2cOptions
-      -DRE2C_BUILD_RE2D=OFF
-      -DRE2C_BUILD_RE2HS=OFF
-      -DRE2C_BUILD_RE2JAVA=OFF
-      -DRE2C_BUILD_RE2JS=OFF
-      -DRE2C_BUILD_RE2OCAML=OFF
-      -DRE2C_BUILD_RE2PY=OFF
-      -DRE2C_BUILD_RE2V=OFF
-      -DRE2C_BUILD_RE2ZIG=OFF
-      -DRE2C_BUILD_TESTS=OFF
+    list(
+      APPEND
+      options
+        -DRE2C_BUILD_RE2D=OFF
+        -DRE2C_BUILD_RE2HS=OFF
+        -DRE2C_BUILD_RE2JAVA=OFF
+        -DRE2C_BUILD_RE2JS=OFF
+        -DRE2C_BUILD_RE2OCAML=OFF
+        -DRE2C_BUILD_RE2PY=OFF
+        -DRE2C_BUILD_RE2V=OFF
+        -DRE2C_BUILD_RE2ZIG=OFF
+        -DRE2C_BUILD_TESTS=OFF
     )
   else()
-    set(
-      re2cOptions
-      -DCMAKE_DISABLE_FIND_PACKAGE_Python3=TRUE
-      -DPython3_VERSION=3.7
+    list(
+      APPEND
+      options
+        -DCMAKE_DISABLE_FIND_PACKAGE_Python3=TRUE
+        -DPython3_VERSION=3.7
     )
   endif()
 
   if(RE2C_VERSION VERSION_GREATER_EQUAL 4.2)
-    list(APPEND re2cOptions -DRE2C_BUILD_RE2SWIFT=OFF)
+    list(APPEND options -DRE2C_BUILD_RE2SWIFT=OFF)
   endif()
 
   ExternalProject_Add(
-    re2c
-    URL
-      https://github.com/skvadrik/re2c/archive/refs/tags/${RE2C_VERSION}.tar.gz
-    CMAKE_ARGS
-      -DRE2C_BUILD_RE2GO=OFF
-      -DRE2C_BUILD_RE2RUST=OFF
-      ${re2cOptions}
+    RE2C
+    STEP_TARGETS build
+    SOURCE_DIR ${re2c_SOURCE_DIR}
+    BINARY_DIR ${re2c_BINARY_DIR}
+    CMAKE_ARGS ${options}
     INSTALL_COMMAND ""
   )
 
-  ExternalProject_Get_Property(re2c BINARY_DIR)
-  set(re2c ${BINARY_DIR}/re2c)
-  if(CMAKE_SYSTEM_NAME STREQUAL "Windows")
-    string(APPEND re2c ".exe")
-  endif()
-  set_property(CACHE RE2C_EXECUTABLE PROPERTY VALUE ${re2c})
+  set_property(
+    CACHE RE2C_EXECUTABLE
+    PROPERTY VALUE ${re2c_BINARY_DIR}/re2c${CMAKE_EXECUTABLE_SUFFIX}
+  )
 
   add_executable(RE2C::RE2C IMPORTED GLOBAL)
   set_target_properties(
     RE2C::RE2C
     PROPERTIES IMPORTED_LOCATION ${RE2C_EXECUTABLE}
   )
-  add_dependencies(RE2C::RE2C re2c)
+  add_dependencies(RE2C::RE2C RE2C-build)
 
   # Move dependency to PACKAGES_FOUND.
   block()
@@ -690,7 +703,7 @@ function(_php_re2c_download)
     _PHP_RE2C_DOWNLOAD
     TRUE
     CACHE INTERNAL
-    "Internal marker whether the re2c will be downloaded."
+    "Internal marker whether the re2c is downloaded."
   )
 
   return(PROPAGATE RE2C_FOUND RE2C_VERSION)