[rollup] 2021-07-26 (#19157)

* [rollup:2021-07-26 1/6] PR #18783 (@strega-nil)

[scripts-audit] vcpkg_copy_tools and friends

* [rollup:2021-07-26 2/6] PR #18898 (@dg0yt)

[vcpkg] Fix toolchain compatibility with cmake < 3.15

* [rollup:2021-07-26 3/6] PR #18980 (@strega-nil)

[cmake-guidelines] Minor update, for `if()`

* [rollup:2021-07-26 4/6] PR #18981 (@strega-nil)

[scripts-audit] vcpkg_check_linkage

* [rollup:2021-07-26 5/6] PR #19158 (@Hoikas)

[vcpkg.cmake] Fix variable case.

* [rollup:2021-07-26 6/6] PR #18839

[scripts-audit] z_vcpkg_get_cmake_vars

Co-authored-by: nicole mazzuca <[email protected]>

docs/maintainers/cmake-guidelines.md

@@ -35,7 +35,7 @@ We hope that they will make both forwards and backwards compatibility easier.
   Always check for `ARGN` or `arg_UNPARSED_ARGUMENTS`.
   `FATAL_ERROR` when possible, `WARNING` if necessary for backwards compatibility.
 - All `cmake_parse_arguments` must use `PARSE_ARGV`.
-- All `foreach` loops must use `IN LISTS` and `IN ITEMS`.
+- All `foreach` loops must use `IN LISTS`, `IN ITEMS`, or `RANGE`.
 - The variables `${ARGV}` and `${ARGN}` are unreferenced,
   except in helpful messages to the user.
   - (i.e., `message(FATAL_ERROR "blah was passed extra arguments: ${ARGN}")`)
@@ -45,27 +45,68 @@ We hope that they will make both forwards and backwards compatibility easier.
   - Exception: `vcpkg.cmake`'s `find_package`.
 - Scripts in the scripts tree should not be expected to need observable changes
   as part of normal operation.
-  - Example violation: `vcpkg_acquire_msys()` has hard-coded packages and versions that need updating over time due to the MSYS project dropping old packages.
-  - Example exception: `vcpkg_from_sourceforge()` has a list of mirrors which needs maintenance but does not have an observable behavior impact on the callers.
-- All variable expansions are in quotes `""`,
-  except those which are intended to be passed as multiple arguments.
-  - Example:
-  ```cmake
-  set(working_directory "")
-  if(DEFINED arg_WORKING_DIRECTORY)
-    set(working_directory "WORKING_DIRECTORY" "${arg_WORKING_DIRECTORY}")
-  endif()
-  # calls do_the_thing() if NOT DEFINED arg_WORKING_DIRECTORY,
-  # else calls do_the_thing(WORKING_DIRECTORY "${arg_WORKING_DIRECTORY}")
-  do_the_thing(${working_directory})
-  ```
+  - Example violation: `vcpkg_acquire_msys()` has hard-coded packages and versions
+    that need updating over time due to the MSYS project dropping old packages.
+  - Example exception: `vcpkg_from_sourceforge()` has a list of mirrors which
+    needs maintenance, but does not have an observable behavior impact on the callers.
+- Rules for quoting: there are three kinds of arguments in CMake -
+  unquoted (`foo(BAR)`), quoted (`foo("BAR")`), and bracketed (`foo([[BAR]])`).
+  Follow these rules to quote correctly:
+  - If an argument contains a variable expansion `${...}`,
+    it must be quoted.
+    - Exception: a "splat" variable expansion, when one variable will be
+      passed to a function as multiple arguments. In this case, the argument
+      should simply be `${foo}`:
+      ```cmake
+      vcpkg_list(SET working_directory)
+      if(DEFINED "arg_WORKING_DIRECTORY")
+        vcpkg_list(SET working_directory WORKING_DIRECTORY "${arg_WORKING_DIRECTORY}")
+      endif()
+      # calls do_the_thing() if NOT DEFINED arg_WORKING_DIRECTORY,
+      # else calls do_the_thing(WORKING_DIRECTORY "${arg_WORKING_DIRECTORY}")
+      do_the_thing(${working_directory})
+      ```
+  - Otherwise, if the argument contains any escape sequences that are not
+    `\\`, `\"`, or `\$`, that argument must be a quoted argument.
+    - For example: `"foo\nbar"` must be quoted.
+  - Otherwise, if the argument contains a `\`, a `"`, or a `$`,
+    that argument should be bracketed.
+    - Example:
+      ```cmake
+      set(x [[foo\bar]])
+      set(y [=[foo([[bar\baz]])]=])
+      ```
+  - Otherwise, if the argument contains characters that are
+    not alphanumeric or `_`, that argument should be quoted.
+  - Otherwise, the argument should be unquoted.
+  - Exception: arguments to `if()` of type `<variable|string>` should always be quoted:
+    - Both arguments to the comparison operators -
+      `EQUAL`, `STREQUAL`, `VERSION_LESS`, etc.
+    - The first argument to `MATCHES` and `IN_LIST`
+    - Example:
+      ```cmake
+      if("${FOO}" STREQUAL "BAR") # ...
+      if("${BAZ}" EQUAL "0") # ...
+      if("FOO" IN_LIST list_variable) # ...
+      if("${bar}" MATCHES [[a[bcd]+\.[bcd]+]]) # ...
+      ```
+    - For single expressions and for other types of predicates that do not
+    take `<variable|string>`, use the normal rules.
 - There are no "pointer" or "in-out" parameters
   (where a user passes a variable name rather than the contents),
   except for simple out-parameters.
 - Variables are not assumed to be empty.
   If the variable is intended to be used locally,
-  it must be explicitly initialized to empty with `set(foo "")`.
-- All variables expected to be inherited from the parent scope across an API boundary (i.e. not a file-local function) should be documented. Note that all variables mentioned in triplets.md are considered documented.
+  it must be explicitly initialized to empty with `set(foo "")` if it is a string variable,
+  and `vcpkg_list(SET foo)` if it is a list variable.
+- `set(var)` should not be used. Use `unset(var)` to unset a variable,
+  `set(var "")` to set it to the empty string,
+  and `vcpkg_list(SET var)` to set it to the empty list.
+  _Note: the empty string and the empty list are the same value;_
+  _this is a notational difference rather than a difference in result_
+- All variables expected to be inherited from the parent scope across an API boundary
+  (i.e. not a file-local function) should be documented.
+  Note that all variables mentioned in triplets.md are considered documented.
 - Out parameters are only set in `PARENT_SCOPE` and are never read.
   See also the helper `z_vcpkg_forward_output_variable()` to forward out parameters through a function scope.
 - `CACHE` variables are used only for global variables which are shared internally among strongly coupled
@@ -80,16 +121,14 @@ We hope that they will make both forwards and backwards compatibility easier.
   and `<start>` _must always be_ less than or equal to `<stop>`.
   - This must be checked by something like:
   ```cmake
-  if(start LESS_EQUAL end)
-    foreach(RANGE start end)
+  if("${start}" LESS_EQUAL "${end}")
+    foreach(RANGE "${start}" "${end}")
       ...
     endforeach()
   endif()
   ```
 - All port-based scripts must use `include_guard(GLOBAL)`
   to avoid being included multiple times.
-- `set(var)` should not be used. Use `unset(var)` to unset a variable,
-  and `set(var "")` to set it to the empty value. _Note: this works for use as a list and as a string_
 
 ### CMake Versions to Require
 

docs/maintainers/internal/z_vcpkg_get_cmake_vars.md

@@ -0,0 +1,36 @@
+# z_vcpkg_get_cmake_vars
+
+The latest version of this document lives in the [vcpkg repo](https://github.com/Microsoft/vcpkg/blob/master/docs/).
+
+**Only for internal use in vcpkg helpers. Behavior and arguments will change without notice.**
+Runs a cmake configure with a dummy project to extract certain cmake variables
+
+## Usage
+```cmake
+z_vcpkg_get_cmake_vars(<out-var>)
+```
+
+`z_vcpkg_get_cmake_vars(cmake_vars_file)` sets `<out-var>` to
+a path to a generated CMake file, with the detected `CMAKE_*` variables
+re-exported as `VCPKG_DETECTED_*`.
+
+## Notes
+Avoid usage in portfiles. 
+
+All calls to `z_vcpkg_get_cmake_vars` will result in the same output file;
+the output file is not generated multiple times.
+
+## Examples
+
+* [vcpkg_configure_make](https://github.com/Microsoft/vcpkg/blob/master/scripts/cmake/vcpkg_configure_make.cmake)
+
+### Basic Usage
+
+```cmake
+z_vcpkg_get_cmake_vars(cmake_vars_file)
+include("${cmake_vars_file}")
+message(STATUS "detected CXX flags: ${VCPKG_DETECTED_CXX_FLAGS}")
+```
+
+## Source
+[scripts/cmake/z\_vcpkg\_get\_cmake\_vars.cmake](https://github.com/Microsoft/vcpkg/blob/master/scripts/cmake/z_vcpkg_get_cmake_vars.cmake)

docs/maintainers/portfile-functions.md

@@ -57,10 +57,10 @@
 
 ## Internal Functions
 
-- [vcpkg\_internal\_get\_cmake\_vars](internal/vcpkg_internal_get_cmake_vars.md)
 - [z\_vcpkg\_apply\_patches](internal/z_vcpkg_apply_patches.md)
 - [z\_vcpkg\_forward\_output\_variable](internal/z_vcpkg_forward_output_variable.md)
 - [z\_vcpkg\_function\_arguments](internal/z_vcpkg_function_arguments.md)
+- [z\_vcpkg\_get\_cmake\_vars](internal/z_vcpkg_get_cmake_vars.md)
 - [z\_vcpkg\_prettify\_command\_line](internal/z_vcpkg_prettify_command_line.md)
 
 ## Scripts from Ports
@@ -69,6 +69,7 @@
 
 - [vcpkg\_cmake\_build](ports/vcpkg-cmake/vcpkg_cmake_build.md)
 - [vcpkg\_cmake\_configure](ports/vcpkg-cmake/vcpkg_cmake_configure.md)
+- [vcpkg\_cmake\_get\_vars](ports/vcpkg-cmake/vcpkg_cmake_get_vars.md)
 - [vcpkg\_cmake\_install](ports/vcpkg-cmake/vcpkg_cmake_install.md)
 
 ### [vcpkg-cmake-config](ports/vcpkg-cmake-config.md)

docs/maintainers/ports/vcpkg-cmake/vcpkg_cmake_get_vars.md

@@ -0,0 +1,31 @@
+# vcpkg_cmake_get_vars
+
+The latest version of this document lives in the [vcpkg repo](https://github.com/Microsoft/vcpkg/blob/master/docs/maintainers/ports/vcpkg-cmake/vcpkg_cmake_get_vars.md).
+
+Runs a cmake configure with a dummy project to extract certain cmake variables
+
+## Usage
+```cmake
+vcpkg_cmake_get_vars(<out-var>)
+```
+
+`vcpkg_cmake_get_vars(<out-var>)` sets `<out-var>` to
+a path to a generated CMake file, with the detected `CMAKE_*` variables
+re-exported as `VCPKG_DETECTED_CMAKE_*`.
+
+## Notes
+Avoid usage in portfiles.
+
+All calls to `vcpkg_cmake_get_vars` will result in the same output file;
+the output file is not generated multiple times.
+
+### Basic Usage
+
+```cmake
+vcpkg_cmake_get_vars(cmake_vars_file)
+include("${cmake_vars_file}")
+message(STATUS "detected CXX flags: ${VCPKG_DETECTED_CMAKE_CXX_FLAGS}")
+```
+
+## Source
+[ports/vcpkg-cmake/vcpkg\_cmake\_get\_vars.cmake](https://github.com/Microsoft/vcpkg/blob/master/ports/vcpkg-cmake/vcpkg_cmake_get_vars.cmake)

docs/regenerate.ps1

@@ -222,7 +222,7 @@ function ParseCmakeDocComment
 
 Get-ChildItem "$VcpkgRoot/scripts/cmake" -Filter '*.cmake' | ForEach-Object {
     $docs = ParseCmakeDocComment $_
-    [Bool]$isInternalFunction = $_.Name.StartsWith("vcpkg_internal") -or $_.Name.StartsWith("z_vcpkg")
+    [Bool]$isInternalFunction = $_.Name.StartsWith("z_vcpkg")
 
     if ($docs.IsDeprecated -and $null -eq $docs.ActualDocumentation)
     {

ports/ffmpeg/portfile.cmake

@@ -544,9 +544,8 @@ else()
     set(OPTIONS "${OPTIONS} --disable-zlib")
 endif()
 
-set(CMAKE_VARS_FILE "${CURRENT_BUILDTREES_DIR}/vars.cmake")
-vcpkg_internal_get_cmake_vars(OUTPUT_FILE CMAKE_VARS_FILE)
-include("${CMAKE_VARS_FILE}")
+vcpkg_cmake_get_vars(cmake_vars_file)
+include("${cmake_vars_file}")
 
 if (VCPKG_TARGET_IS_OSX)
     # if the sysroot isn't set in the triplet we fall back to whatever CMake detected for us

ports/ffmpeg/vcpkg.json

@@ -1,13 +1,17 @@
 {
   "name": "ffmpeg",
   "version": "4.4",
-  "port-version": 11,
+  "port-version": 12,
   "description": [
     "a library to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created.",
     "FFmpeg is the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created. It supports the most obscure ancient formats up to the cutting edge. No matter if they were designed by some standards committee, the community or a corporation. It is also highly portable: FFmpeg compiles, runs, and passes our testing infrastructure FATE across Linux, Mac OS X, Microsoft Windows, the BSDs, Solaris, etc. under a wide variety of build environments, machine architectures, and configurations."
   ],
   "homepage": "https://ffmpeg.org",
   "dependencies": [
+    {
+      "name": "vcpkg-cmake",
+      "host": true
+    },
     {
       "name": "vcpkg-pkgconfig-get-modules",
       "host": true