[FileCheck] Given multiple -dump-input, prefer most verbose

Problem: `FILECHECK_OPTS` was implemented so that a test runner, such
as a bot, can specify FileCheck debugging options, such as
`-dump-input=fail`.  However, some existing test suites have FileCheck
calls that already specify `-dump-input=fail` or `-dump-input=always`.
Without this patch, such tests fail under such a test runner because
FileCheck doesn't accept multiple occurrences of `-dump-input`.

Solution: This patch permits multiple occurrences of `-dump-input` by
assigning precedence to its values in the following descending order:
`help`, `always`, `fail`, and `never`.  That is, any occurrence of
`help` always obtains help, and otherwise the behavior is similar to
`-v` vs. `-vv` in that the option specifying the greatest verbosity
has precedence.

Rationale: My justification for the new behavior is as follows.  I
have not experienced use cases where, either as a test runner or as a
test author, I want to **limit** the permitted debugging verbosity
(except as a test author in FileCheck's or lit's test suites where the
FileCheck debugging output itself is under test, but the solution
there is `env FILECHECK_OPTS=`, and I imagine we should use the same
solution anywhere else this need might occur).  Of course, as either a
test runner or test author, it is useful to **increase** debugging
verbosity.

Reviewed By: probinson

Differential Revision: https://reviews.llvm.org/D70784

1 files changed, 15 insertions, 7 deletions

diff --git a/llvm/utils/FileCheck/FileCheck.cpp b/llvm/utils/FileCheck/FileCheck.cpp
index 44d5be1..6f579135 100644
--- a/llvm/utils/FileCheck/FileCheck.cpp
+++ b/llvm/utils/FileCheck/FileCheck.cpp
@@ -108,24 +108,28 @@ static cl::opt<bool> DumpInputOnFailure(
              "FILECHECK_DUMP_INPUT_ON_FAILURE environment variable.\n"
              "This option is deprecated in favor of -dump-input=fail.\n"));
 
+// The order of DumpInputValue members affects their precedence, as documented
+// for -dump-input below.
 enum DumpInputValue {
   DumpInputDefault,
-  DumpInputHelp,
   DumpInputNever,
   DumpInputFail,
-  DumpInputAlways
+  DumpInputAlways,
+  DumpInputHelp
 };
 
-static cl::opt<DumpInputValue> DumpInput(
-    "dump-input", cl::init(DumpInputDefault),
+static cl::list<DumpInputValue> DumpInputs(
+    "dump-input",
     cl::desc("Dump input to stderr, adding annotations representing\n"
-             " currently enabled diagnostics\n"),
+             "currently enabled diagnostics.  When there are multiple\n"
+             "occurrences of this option, the <value> that appears earliest\n"
+             "in the list below has precedence.\n"),
     cl::value_desc("mode"),
     cl::values(clEnumValN(DumpInputHelp, "help",
                           "Explain dump format and quit"),
-               clEnumValN(DumpInputNever, "never", "Never dump input"),
+               clEnumValN(DumpInputAlways, "always", "Always dump input"),
                clEnumValN(DumpInputFail, "fail", "Dump input on failure"),
-               clEnumValN(DumpInputAlways, "always", "Always dump input")));
+               clEnumValN(DumpInputNever, "never", "Never dump input")));
 
 typedef cl::list<std::string>::const_iterator prefix_iterator;
 
@@ -516,6 +520,10 @@ int main(int argc, char **argv) {
   InitLLVM X(argc, argv);
   cl::ParseCommandLineOptions(argc, argv, /*Overview*/ "", /*Errs*/ nullptr,
                               "FILECHECK_OPTS");
+  DumpInputValue DumpInput =
+      DumpInputs.empty()
+          ? DumpInputDefault
+          : *std::max_element(DumpInputs.begin(), DumpInputs.end());
   if (DumpInput == DumpInputHelp) {
     DumpInputAnnotationHelp(outs());
     return 0;