[lit] Add readfile substitution

llvm/utils/lit/lit/TestRunner.py

@@ -720,7 +720,7 @@ def processRedirects(cmd, stdin_source, cmd_shenv, opened_files):
     return std_fds
 
 
-def _expandLateSubstitutions(arguments, cwd):
+def _expandLateSubstitutions(cmd, arguments, cwd):
     for i, arg in enumerate(arguments):
         if not isinstance(arg, str):
             continue
@@ -729,8 +729,11 @@ def _replaceReadFile(match):
             filePath = match.group(1)
             if not os.path.isabs(filePath):
                 filePath = os.path.join(cwd, filePath)
-            with open(filePath) as fileHandle:
-                return fileHandle.read()
+            try:
+                with open(filePath) as fileHandle:
+                    return fileHandle.read()
+            except FileNotFoundError:
+                raise InternalShellError(cmd, "File does not exist: %s" % filePath)
 
         arguments[i] = re.sub(r"%{readfile:([^}]*)}", _replaceReadFile, arg)
 
@@ -852,7 +855,7 @@ def _executeShCmd(cmd, shenv, results, timeoutHelper):
         args[0] = expand_glob(args[0], cmd_shenv.cwd)[0]
 
         # Expand all late substitutions.
-        args = _expandLateSubstitutions(args, cmd_shenv.cwd)
+        args = _expandLateSubstitutions(j, args, cmd_shenv.cwd)
 
         inproc_builtin = inproc_builtins.get(args[0], None)
         if inproc_builtin and (args[0] != "echo" or len(cmd.commands) == 1):

llvm/utils/lit/tests/Inputs/shtest-readfile/file-does-not-exist.txt

@@ -0,0 +1,4 @@
+## Test that readfile reports information appropriately when the file specified
+## does not exist.
+
+# RUN: echo %{readfile:/file/does/not/exist}

llvm/utils/lit/tests/shtest-readfile.py

@@ -2,12 +2,16 @@
 
 # RUN: not %{lit} -a -v %{inputs}/shtest-readfile | FileCheck -match-full-lines -DTEMP_PATH=%S/Inputs/shtest-readfile/Output %s
 
-# CHECK: -- Testing: 3 tests{{.*}}
+# CHECK: -- Testing: 4 tests{{.*}}
 
 # CHECK-LABEL: FAIL: shtest-readfile :: absolute-paths.txt ({{[^)]*}})
 # CHECK: echo hello
 # CHECK: # executed command: echo '%{readfile:[[TEMP_PATH]]/absolute-paths.txt.tmp}'
 
+# CHECK-LABEL: FAIL: shtest-readfile :: file-does-not-exist.txt ({{[^)]*}})
+# CHECK: # executed command: @echo 'echo %{readfile:/file/does/not/exist}'
+# CHECK: # | File does not exist: /file/does/not/exist
+
 # CHECK-LABEL: FAIL: shtest-readfile :: relative-paths.txt ({{[^)]*}})
 # CHECK: echo hello
 # CHECK: # executed command: echo '%{readfile:rel_path_test_folder/test_file}'