[lit] add lit_config.substitute to interpolate lit_config.params

[sammccall]

Summary

A version of this logic appears in ~every lit.site.cfg.in (28 copies total).
This patch just removes two, but I'll update the rest of llvm-project next.

[hokein]

This patch is definitely an improvement.

clang-tools-extra/clangd/test/lit.site.cfg.py.in

 @LIT_SITE_CFG_IN_HEADER@
 
 # Variables needed for common clang config.
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
-config.clang_tools_dir = "@CLANG_TOOLS_DIR@"
-config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
 config.clang_libs_dir = "@CLANG_LIBS_DIR@"
-config.llvm_libs_dir = "@LLVM_LIBS_DIR@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.python_executable = "@Python3_EXECUTABLE@"
-
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
-try:
-    config.clang_tools_dir = config.clang_tools_dir % lit_config.params
-    config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
-    config.llvm_libs_dir = config.llvm_libs_dir % lit_config.params
-except KeyError:
-    e = sys.exc_info()[1]
-    key, = e.args
-    lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
+config.clang_tools_dir = lit_config.substitute("@CLANG_TOOLS_DIR@")
+config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
+config.llvm_libs_dir = lit_config.substitute("@LLVM_LIBS_DIR@")
 
 config.clangd_source_dir = "@CMAKE_CURRENT_SOURCE_DIR@/.."
 config.clangd_binary_dir = "@CMAKE_CURRENT_BINARY_DIR@/.."
 config.clangd_build_xpc = @CLANGD_BUILD_XPC@
 config.clangd_enable_remote = @CLANGD_ENABLE_REMOTE@
 config.clangd_tidy_checks = @CLANGD_TIDY_CHECKS@
 config.have_zlib = @LLVM_ENABLE_ZLIB@
 
 # Delegate logic to lit.cfg.py.
 lit_config.load_config(config, "@CMAKE_CURRENT_SOURCE_DIR@/lit.cfg.py")

clang-tools-extra/test/lit.site.cfg.py.in

 @LIT_SITE_CFG_IN_HEADER@
 
 import sys
 
-config.llvm_tools_dir = "@LLVM_TOOLS_DIR@"
-config.llvm_libs_dir = "@LLVM_LIBS_DIR@"
 config.llvm_plugin_ext = "@LLVM_PLUGIN_EXT@"
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.clang_tools_binary_dir = "@CLANG_TOOLS_BINARY_DIR@"
-config.clang_tools_dir = "@CLANG_TOOLS_DIR@"
 config.clang_libs_dir = "@SHLIBDIR@"
 config.python_executable = "@Python3_EXECUTABLE@"
 config.target_triple = "@TARGET_TRIPLE@"
 config.clang_tidy_staticanalyzer = @CLANG_TIDY_ENABLE_STATIC_ANALYZER@
 config.has_plugins = @CLANG_PLUGIN_SUPPORT@ & ~@LLVM_INSTALL_TOOLCHAIN_ONLY@
-
 # Support substitution of the tools and libs dirs with user parameters. This is
 # used when we can't determine the tool dir at configuration time.
-try:
-    config.clang_tools_dir = config.clang_tools_dir % lit_config.params
-    config.llvm_tools_dir = config.llvm_tools_dir % lit_config.params
-    config.llvm_libs_dir = config.llvm_libs_dir % lit_config.params
-except KeyError:
-    e = sys.exc_info()[1]
-    key, = e.args
-    lit_config.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (key,key))
+config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
+config.llvm_libs_dir = lit_config.substitute("@LLVM_LIBS_DIR@")
+config.clang_tools_dir = lit_config.substitute("@CLANG_TOOLS_DIR@")
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@CLANG_TOOLS_SOURCE_DIR@/test/lit.cfg.py")

llvm/utils/lit/lit/LitConfig.py

def _write_message(self, kind, message):
         sys.stderr.write('%s: %s:%d: %s: %s\n' % (self.progname, file, line,
                                                   kind, message))
         if self.isWindows:
             # In a git bash terminal, the writes to sys.stderr aren't visible
             # on screen immediately. Flush them here to avoid broken/misoredered
             # output.
             sys.stderr.flush()
 
+    def substitute(self, string):
+        """substitute - Interpolate params into a string"""
+        try:
+          return string % self.params
+        except KeyError as e:
+          key, = e.args
+          self.fatal("unable to find %r parameter, use '--param=%s=VALUE'" % (
+              key,key))
+
     def note(self, message):
         if not self.quiet:
             self._write_message('note', message)
 
     def warning(self, message):
         if not self.quiet:
             self._write_message('warning', message)
         self.numWarnings += 1
 
     def error(self, message):
         self._write_message('error', message)
         self.numErrors += 1
 
     def fatal(self, message):
         self._write_message('fatal', message)
         sys.exit(2)