[FileCheck] Annotate input dump (6/7)

This patch implements input annotations for diagnostics reporting
CHECK-DAG discarded matches.  These diagnostics are enabled by -vv.
These annotations mark discarded match ranges using `!~~` because they
are bad matches even though they are not errors.

CHECK-DAG discarded matches create another case where there can be
multiple match results for the same directive.

For example:

```
$ FileCheck -dump-input=help
The following description was requested by -dump-input=help to
explain the input annotations printed by -dump-input=always and
-dump-input=fail:

  - L:     labels line number L of the input file
  - T:L    labels the only match result for a pattern of type T from line L of
           the check file
  - T:L'N  labels the Nth match result for a pattern of type T from line L of
           the check file
  - ^~~    marks good match (reported if -v)
  - !~~    marks bad match, such as:
           - CHECK-NEXT on same line as previous match (error)
           - CHECK-NOT found (error)
           - CHECK-DAG overlapping match (discarded, reported if -vv)
  - X~~    marks search range when no match is found, such as:
           - CHECK-NEXT not found (error)
           - CHECK-DAG not found after discarded matches (error)
  - ?      marks fuzzy match when no match is found
  - colors success, error, fuzzy match, discarded match, unmatched input

If you are not seeing color above or in input dumps, try: -color

$ FileCheck -vv -dump-input=always check4 < input4 |& sed -n '/^<<<</,$p'
<<<<<<
         1: abcdef
dag:1       ^~~~
dag:2'0       !~~~ discard: overlaps earlier match
         2: cdefgh
dag:2'1     ^~~~
check:3         X~ error: no match found
>>>>>>

$ cat check4
CHECK-DAG: abcd
CHECK-DAG: cdef
CHECK: efgh

$ cat input4
abcdef
cdefgh
```

This shows that the line 3 CHECK fails to match even though its
pattern appears in the input because its search range starts after the
line 2 CHECK-DAG's match range.  The trouble might be that the line 2
CHECK-DAG's match range is later than expected because its first match
range overlaps with the line 1 CHECK-DAG match range and thus is
discarded.

Because `!~~` for CHECK-DAG does not indicate an error, it is not
colored red.  Instead, when colors are enabled, it is colored cyan,
which suggests a match that went cold.

Reviewed By: george.karpenkov, probinson

Differential Revision: https://reviews.llvm.org/D53898

llvm-svn: 349423

llvm/include/llvm/Support/FileCheck.h

@@ -160,7 +160,8 @@ struct FileCheckDiag {
   /// What kind of match result does this diagnostic describe?
   ///
   /// There might be more than one of these for the same directive.  For
-  /// example, there might be a fuzzy match after a fail.
+  /// example, there might be several discards before either a final or fail,
+  /// and there might be a fuzzy match after a fail.
   enum MatchType {
     // TODO: More members will appear with later patches in this series.
     /// Indicates the final match for an expected pattern.
@@ -170,6 +171,8 @@ struct FileCheckDiag {
     /// Indicates the final match for an expected pattern, but the match is on
     /// the wrong line.
     MatchFinalButWrongLine,
+    /// Indicates a discarded match for an expected pattern.
+    MatchDiscard,
     /// Indicates no match for an expected pattern.
     MatchNoneButExpected,
     /// Indicates a possible intended match because there's no perfect match.

llvm/lib/Support/FileCheck.cpp

@@ -1284,7 +1284,7 @@ FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
                         "match discarded, overlaps earlier DAG match here",
                         {OldRange});
         if (Diags)
-          Diags->pop_back();
+          Diags->rbegin()->MatchTy = FileCheckDiag::MatchDiscard;
       }
       MatchPos = MI->End;
     }

llvm/test/FileCheck/dump-input-annotations.txt

@@ -302,7 +302,7 @@
 ; NOT2-NOT:     {{.}}
 
 ;--------------------------------------------------
-; CHECK-DAG (also: matches in different order than directives)
+; CHECK-DAG (also: matches in different order than directives, discarded match)
 ;--------------------------------------------------
 
 ; Good match, discarded match plus good match, and no match.
@@ -319,18 +319,23 @@
 ; RUN: not FileCheck -dump-input=always -input-file %t.in %t.chk 2>&1 \
 ; RUN: | FileCheck -match-full-lines %s -check-prefixes=DAG,DAG-Q
 ; RUN: not FileCheck -dump-input=always -input-file %t.in %t.chk -v 2>&1 \
-; RUN: | FileCheck -match-full-lines %s -check-prefixes=DAG,DAG-V
+; RUN: | FileCheck -match-full-lines %s -check-prefixes=DAG,DAG-V,DAG-VQ
 ; RUN: not FileCheck -dump-input=always -input-file %t.in %t.chk -vv 2>&1 \
 ; RUN: | FileCheck -match-full-lines %s -check-prefixes=DAG,DAG-V,DAG-VV
 
 ; DAG:         <<<<<<
 ; DAG-NEXT:             1: abc
 ; DAG-V-NEXT:  dag:2       ^~~
+; DAG-VV-NEXT: dag:3'0     !~~ discard: overlaps earlier match
 ; DAG-NEXT:             2: def
 ; DAG-V-NEXT:  dag:1       ^~~
+; DAG-VV-NEXT: dag:4'0     !~~ discard: overlaps earlier match
 ; DAG-NEXT:             3: abc
-; DAG-V-NEXT:  dag:3       ^~~
-; DAG-NEXT:    dag:4       X~~ error: no match found
+; DAG-VQ-NEXT: dag:3       ^~~
+; DAG-VV-NEXT: dag:3'1     ^~~
+; DAG-Q-NEXT:  dag:4       X~~ error: no match found
+; DAG-VQ-NEXT: dag:4       X~~ error: no match found
+; DAG-VV-NEXT: dag:4'1     X~~ error: no match found
 ; DAG-NEXT:    >>>>>>
 ; DAG-NOT:     {{.}}
 

llvm/utils/FileCheck/FileCheck.cpp

@@ -150,6 +150,9 @@ static MarkerStyle GetMarker(FileCheckDiag::MatchType MatchTy) {
     return MarkerStyle('!', raw_ostream::RED, "error: no match expected");
   case FileCheckDiag::MatchFinalButWrongLine:
     return MarkerStyle('!', raw_ostream::RED, "error: match on wrong line");
+  case FileCheckDiag::MatchDiscard:
+    return MarkerStyle('!', raw_ostream::CYAN,
+                       "discard: overlaps earlier match");
   case FileCheckDiag::MatchNoneButExpected:
     return MarkerStyle('X', raw_ostream::RED, "error: no match found");
   case FileCheckDiag::MatchFuzzy:
@@ -191,10 +194,13 @@ static void DumpInputAnnotationHelp(raw_ostream &OS) {
   OS << "    marks bad match, such as:\n"
      << "           - CHECK-NEXT on same line as previous match (error)\n"
      << "           - CHECK-NOT found (error)\n"
+     << "           - CHECK-DAG overlapping match (discarded, reported if "
+     << "-vv)\n"
      << "  - ";
   WithColor(OS, raw_ostream::SAVEDCOLOR, true) << "X~~";
   OS << "    marks search range when no match is found, such as:\n"
      << "           - CHECK-NEXT not found (error)\n"
+     << "           - CHECK-DAG not found after discarded matches (error)\n"
      << "  - ";
   WithColor(OS, raw_ostream::SAVEDCOLOR, true) << "?";
   OS << "      marks fuzzy match when no match is found\n";
@@ -207,6 +213,8 @@ static void DumpInputAnnotationHelp(raw_ostream &OS) {
   OS << ", ";
   WithColor(OS, raw_ostream::MAGENTA, true) << "fuzzy match";
   OS << ", ";
+  WithColor(OS, raw_ostream::CYAN, true, false) << "discarded match";
+  OS << ", ";
   WithColor(OS, raw_ostream::CYAN, true, true) << "unmatched input";
   OS << "\n\n"
      << "If you are not seeing color above or in input dumps, try: -color\n";