[build-script] Add test for --skip-build-* options and a lit variable for cmake

This was backported from a313f62 with all the
--infer and --install-all work there left out, bringing back a single test and
the lit variable for cmake that it used.

One note describing that from the original commit:

2. I added %cmake as a lit variable. I did this so I could specify in
   my build-system unit tests that on Linux they should use the just
   built cmake (if we built cmake due to an old cmake being on the
   system). Otherwise, the build system unit tests took way too
   long. These are meant to be dry-runs, so building this cmake again
   is just wasteful and doesn't make sense.

Author: gottesmm

test/lit.cfg

@@ -199,6 +199,11 @@ config.test_source_root = os.path.dirname(__file__)
 # test_exec_root: The root path where tests should be run.
 swift_obj_root = getattr(config, 'swift_obj_root', None)
 
+# cmake. The path to the cmake executable we used to configure swift.
+assert(config.cmake)
+config.substitutions.append( ('%cmake',  config.cmake) )
+lit_config.note('Using cmake: ' + config.cmake)
+
 # Set llvm_{src,obj}_root for use by others.
 config.llvm_src_root = getattr(config, 'llvm_src_root', None)
 config.llvm_obj_root = getattr(config, 'llvm_obj_root', None)

test/lit.site.cfg.in

@@ -14,6 +14,7 @@ import os
 import platform
 import sys
 
+config.cmake = "@CMAKE_COMMAND@"
 config.llvm_src_root = "@LLVM_MAIN_SRC_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"

utils/swift_build_support/swift_build_support/cmake.py

@@ -272,7 +272,7 @@ def check_cmake_version(self, source_root, build_root):
             cmake_binary = 'cmake'
 
         installed_ver = self.installed_cmake_version(cmake_binary)
-        if installed_ver > self.cmake_source_version(cmake_source_dir):
+        if installed_ver >= self.cmake_source_version(cmake_source_dir):
             return
         else:
             # Build CMake from source and return the path to the executable.

validation-test/BuildSystem/skip_cmark_swift_llvm.test-sh

@@ -0,0 +1,24 @@
+# RUN: %empty-directory(%t)
+# RUN: mkdir -p %t
+# RUN: SWIFT_BUILD_ROOT=%t %swift_src_root/utils/build-script --dry-run --cmake %cmake --skip-build-cmark 2>&1 | %FileCheck --check-prefix=SKIP-CMARK-CHECK %s
+
+# RUN: %empty-directory(%t)
+# RUN: mkdir -p %t
+# RUN: SWIFT_BUILD_ROOT=%t %swift_src_root/utils/build-script --dry-run --cmake %cmake --skip-build-llvm 2>&1 | %FileCheck --check-prefix=SKIP-LLVM-CHECK %s
+
+# RUN: %empty-directory(%t)
+# RUN: mkdir -p %t
+# RUN: SWIFT_BUILD_ROOT=%t %swift_src_root/utils/build-script --dry-run --cmake %cmake --skip-build-swift 2>&1 | %FileCheck --check-prefix=SKIP-SWIFT-CHECK %s
+
+# SKIP-CMARK-CHECK-NOT: cmake --build {{.*}}cmark-
+# SKIP-CMARK-CHECK: cmake --build {{.*}}llvm-
+# SKIP-CMARK-CHECK: cmake --build {{.*}}swift-
+
+# SKIP-LLVM-CHECK: cmake --build {{.*}}cmark-
+# SKIP-LLVM-CHECK-NOT: cmake --build {{.*}}llvm-
+# SKIP-LLVM-CHECK: cmake --build {{.*}}swift-
+
+# SKIP-SWIFT-CHECK: cmake --build {{.*}}cmark-
+# SKIP-SWIFT-CHECK: cmake --build {{.*}}llvm-
+# SKIP-SWIFT-CHECK-NOT: cmake --build {{.*}}swift-
+

validation-test/lit.site.cfg.in

@@ -13,6 +13,7 @@
 import sys
 import platform
 
+config.cmake = "@CMAKE_COMMAND@"
 config.llvm_src_root = "@LLVM_MAIN_SRC_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"