[FileCheck]: Fix diagnostics for NOT prefixes (#78412)

Fixes #70221 

Fix a bug in FileCheck that corrects the error message when multiple
prefixes are provided
through --check-prefixes and one of them is a PREFIX-NOT.

Earlier, only the first of the provided prefixes was displayed as the
erroneous prefix, while the
actual error might be on the prefix that occurred at the end of the
prefix list in the input file.

Now, the right NOT prefix is shown in the error message.

6 files changed, 126 insertions, 42 deletions

diff --git a/llvm/lib/FileCheck/FileCheck.cpp b/llvm/lib/FileCheck/FileCheck.cpp
index b728c14..0d5bdf7 100644
--- a/llvm/lib/FileCheck/FileCheck.cpp
+++ b/llvm/lib/FileCheck/FileCheck.cpp
@@ -1784,7 +1784,7 @@ bool FileCheck::readCheckFile(
 
   PatternContext->createLineVariable();
 
-  std::vector<Pattern> ImplicitNegativeChecks;
+  std::vector<FileCheckString::DagNotPrefixInfo> ImplicitNegativeChecks;
   for (StringRef PatternString : Req.ImplicitCheckNot) {
     // Create a buffer with fake command line content in order to display the
     // command line option responsible for the specific implicit CHECK-NOT.
@@ -1807,14 +1807,15 @@ bool FileCheck::readCheckFile(
       }
     }
 
-    ImplicitNegativeChecks.push_back(
-        Pattern(Check::CheckNot, PatternContext.get()));
-    ImplicitNegativeChecks.back().parsePattern(PatternInBuffer,
-                                               "IMPLICIT-CHECK", SM, Req);
+    ImplicitNegativeChecks.emplace_back(
+        Pattern(Check::CheckNot, PatternContext.get()),
+        StringRef("IMPLICIT-CHECK"));
+    ImplicitNegativeChecks.back().DagNotPat.parsePattern(
+        PatternInBuffer, "IMPLICIT-CHECK", SM, Req);
   }
 
-  std::vector<Pattern> DagNotMatches = ImplicitNegativeChecks;
-
+  std::vector<FileCheckString::DagNotPrefixInfo> DagNotMatches =
+      ImplicitNegativeChecks;
   // LineNumber keeps track of the line on which CheckPrefix instances are
   // found.
   unsigned LineNumber = 1;
@@ -1926,7 +1927,7 @@ bool FileCheck::readCheckFile(
 
     // Handle CHECK-DAG/-NOT.
     if (CheckTy == Check::CheckDAG || CheckTy == Check::CheckNot) {
-      DagNotMatches.push_back(P);
+      DagNotMatches.emplace_back(P, UsedPrefix);
       continue;
     }
 
@@ -2165,7 +2166,7 @@ size_t FileCheckString::Check(const SourceMgr &SM, StringRef Buffer,
                               FileCheckRequest &Req,
                               std::vector<FileCheckDiag> *Diags) const {
   size_t LastPos = 0;
-  std::vector<const Pattern *> NotStrings;
+  std::vector<const DagNotPrefixInfo *> NotStrings;
 
   // IsLabelScanMode is true when we are scanning forward to find CHECK-LABEL
   // bounds; we have not processed variable definitions within the bounded block
@@ -2302,17 +2303,19 @@ bool FileCheckString::CheckSame(const SourceMgr &SM, StringRef Buffer) const {
   return false;
 }
 
-bool FileCheckString::CheckNot(const SourceMgr &SM, StringRef Buffer,
-                               const std::vector<const Pattern *> &NotStrings,
-                               const FileCheckRequest &Req,
-                               std::vector<FileCheckDiag> *Diags) const {
+bool FileCheckString::CheckNot(
+    const SourceMgr &SM, StringRef Buffer,
+    const std::vector<const DagNotPrefixInfo *> &NotStrings,
+    const FileCheckRequest &Req, std::vector<FileCheckDiag> *Diags) const {
   bool DirectiveFail = false;
-  for (const Pattern *Pat : NotStrings) {
-    assert((Pat->getCheckTy() == Check::CheckNot) && "Expect CHECK-NOT!");
-    Pattern::MatchResult MatchResult = Pat->match(Buffer, SM);
-    if (Error Err = reportMatchResult(/*ExpectedMatch=*/false, SM, Prefix,
-                                      Pat->getLoc(), *Pat, 1, Buffer,
-                                      std::move(MatchResult), Req, Diags)) {
+  for (auto NotInfo : NotStrings) {
+    assert((NotInfo->DagNotPat.getCheckTy() == Check::CheckNot) &&
+           "Expect CHECK-NOT!");
+    Pattern::MatchResult MatchResult = NotInfo->DagNotPat.match(Buffer, SM);
+    if (Error Err = reportMatchResult(
+            /*ExpectedMatch=*/false, SM, NotInfo->DagNotPrefix,
+            NotInfo->DagNotPat.getLoc(), NotInfo->DagNotPat, 1, Buffer,
+            std::move(MatchResult), Req, Diags)) {
       cantFail(handleErrors(std::move(Err), [&](const ErrorReported &E) {}));
       DirectiveFail = true;
       continue;
@@ -2321,10 +2324,11 @@ bool FileCheckString::CheckNot(const SourceMgr &SM, StringRef Buffer,
   return DirectiveFail;
 }
 
-size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
-                                 std::vector<const Pattern *> &NotStrings,
-                                 const FileCheckRequest &Req,
-                                 std::vector<FileCheckDiag> *Diags) const {
+size_t
+FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
+                          std::vector<const DagNotPrefixInfo *> &NotStrings,
+                          const FileCheckRequest &Req,
+                          std::vector<FileCheckDiag> *Diags) const {
   if (DagNotStrings.empty())
     return 0;
 
@@ -2344,13 +2348,14 @@ size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
   // group, so we don't use a range-based for loop here.
   for (auto PatItr = DagNotStrings.begin(), PatEnd = DagNotStrings.end();
        PatItr != PatEnd; ++PatItr) {
-    const Pattern &Pat = *PatItr;
+    const Pattern &Pat = PatItr->DagNotPat;
+    const StringRef DNPrefix = PatItr->DagNotPrefix;
     assert((Pat.getCheckTy() == Check::CheckDAG ||
             Pat.getCheckTy() == Check::CheckNot) &&
            "Invalid CHECK-DAG or CHECK-NOT!");
 
     if (Pat.getCheckTy() == Check::CheckNot) {
-      NotStrings.push_back(&Pat);
+      NotStrings.push_back(&*PatItr);
       continue;
     }
 
@@ -2367,7 +2372,7 @@ size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
       // With a group of CHECK-DAGs, a single mismatching means the match on
       // that group of CHECK-DAGs fails immediately.
       if (MatchResult.TheError || Req.VerboseVerbose) {
-        if (Error Err = reportMatchResult(/*ExpectedMatch=*/true, SM, Prefix,
+        if (Error Err = reportMatchResult(/*ExpectedMatch=*/true, SM, DNPrefix,
                                           Pat.getLoc(), Pat, 1, MatchBuffer,
                                           std::move(MatchResult), Req, Diags)) {
           cantFail(
@@ -2430,13 +2435,13 @@ size_t FileCheckString::CheckDag(const SourceMgr &SM, StringRef Buffer,
     }
     if (!Req.VerboseVerbose)
       cantFail(printMatch(
-          /*ExpectedMatch=*/true, SM, Prefix, Pat.getLoc(), Pat, 1, Buffer,
+          /*ExpectedMatch=*/true, SM, DNPrefix, Pat.getLoc(), Pat, 1, Buffer,
           Pattern::MatchResult(MatchPos, MatchLen, Error::success()), Req,
           Diags));
 
     // Handle the end of a CHECK-DAG group.
     if (std::next(PatItr) == PatEnd ||
-        std::next(PatItr)->getCheckTy() == Check::CheckNot) {
+        std::next(PatItr)->DagNotPat.getCheckTy() == Check::CheckNot) {
       if (!NotStrings.empty()) {
         // If there are CHECK-NOTs between two CHECK-DAGs or from CHECK to
         // CHECK-DAG, verify that there are no 'not' strings occurred in that
diff --git a/llvm/lib/FileCheck/FileCheckImpl.h b/llvm/lib/FileCheck/FileCheckImpl.h
index c154616..c772edd 100644
--- a/llvm/lib/FileCheck/FileCheckImpl.h
+++ b/llvm/lib/FileCheck/FileCheckImpl.h
@@ -823,9 +823,19 @@ struct FileCheckString {
   /// The location in the match file that the check string was specified.
   SMLoc Loc;
 
-  /// All of the strings that are disallowed from occurring between this match
-  /// string and the previous one (or start of file).
-  std::vector<Pattern> DagNotStrings;
+  /// Hold the information about the DAG/NOT strings in the program, which are
+  /// not explicitly stored otherwise. This allows for better and more accurate
+  /// diagnostic messages.
+  struct DagNotPrefixInfo {
+    Pattern DagNotPat;
+    StringRef DagNotPrefix;
+
+    DagNotPrefixInfo(const Pattern &P, StringRef S)
+        : DagNotPat(P), DagNotPrefix(S) {}
+  };
+
+  /// Hold the DAG/NOT strings occurring in the input file.
+  std::vector<DagNotPrefixInfo> DagNotStrings;
 
   FileCheckString(const Pattern &P, StringRef S, SMLoc L)
       : Pat(P), Prefix(S), Loc(L) {}
@@ -845,12 +855,12 @@ struct FileCheckString {
   /// \p Buffer. Errors are reported against \p SM and diagnostics recorded in
   /// \p Diags according to the verbosity level set in \p Req.
   bool CheckNot(const SourceMgr &SM, StringRef Buffer,
-                const std::vector<const Pattern *> &NotStrings,
+                const std::vector<const DagNotPrefixInfo *> &NotStrings,
                 const FileCheckRequest &Req,
                 std::vector<FileCheckDiag> *Diags) const;
   /// Matches "dag strings" and their mixed "not strings".
   size_t CheckDag(const SourceMgr &SM, StringRef Buffer,
-                  std::vector<const Pattern *> &NotStrings,
+                  std::vector<const DagNotPrefixInfo *> &NotStrings,
                   const FileCheckRequest &Req,
                   std::vector<FileCheckDiag> *Diags) const;
 };
diff --git a/llvm/test/FileCheck/check-ignore-case.txt b/llvm/test/FileCheck/check-ignore-case.txt
index c3b4d97..47999ff 100644
--- a/llvm/test/FileCheck/check-ignore-case.txt
+++ b/llvm/test/FileCheck/check-ignore-case.txt
@@ -43,6 +43,6 @@ One Line To Match
 # LINE: {{o}}ne line
 # LINE-SAME: {{t}}o match
 
-# ERROR: command line:1:{{[0-9]+}}: error: CHECK-NOT: excluded string found in input
+# ERROR: command line:1:{{[0-9]+}}: error: IMPLICIT-CHECK-NOT: excluded string found in input
 # ERROR-NEXT: -implicit-check-not='sTrInG'
 # ERROR: note: found here
diff --git a/llvm/test/FileCheck/check-not-custom-prefix.txt b/llvm/test/FileCheck/check-not-custom-prefix.txt
new file mode 100644
index 0000000..ddd8a71
--- /dev/null
+++ b/llvm/test/FileCheck/check-not-custom-prefix.txt
@@ -0,0 +1,69 @@
+; Test two trailing NOT strings
+; RUN: rm -f %t && \
+; RUN: echo "LEADING: placeholder1" >>%t && echo "MIDDLE-NOT: placeholder2" >>%t && echo "TRAILING-NOT: placeholder3" >>%t && \
+; RUN: %ProtectFileCheckOutput not FileCheck --strict-whitespace --check-prefixes LEADING,MIDDLE,TRAILING --dump-input=never --input-file  %t %t 2>&1 | \
+; RUN: FileCheck --check-prefix TEST1 %s
+
+; Test NOT string occurring in between two allowable strings
+; RUN: rm -f %t && \
+; RUN: echo "LEADING: placeholder1" >>%t && echo "MIDDLE-NOT: placeholder2" >>%t && echo "TRAILING: placeholder3" >>%t && \
+; RUN: %ProtectFileCheckOutput not FileCheck --strict-whitespace --check-prefixes LEADING,MIDDLE,TRAILING --dump-input=never --input-file  %t %t 2>&1 | \
+; RUN: FileCheck --check-prefix TEST2 %s
+
+; Test first prefix found being the NOT string
+; RUN: rm -f %t && \
+; RUN: echo "LEADING-NOT: placeholder1" >>%t && echo "MIDDLE: placeholder2" >>%t && echo "TRAILING: placeholder3" >>%t && \
+; RUN: %ProtectFileCheckOutput not FileCheck --strict-whitespace --check-prefixes LEADING,MIDDLE,TRAILING --dump-input=never --input-file  %t %t 2>&1 | \
+; RUN: FileCheck --check-prefix TEST3 %s
+
+; Test all given prefixes being NOT strings
+; RUN: rm -f %t && \
+; RUN: echo "LEADING-NOT: placeholder1" >>%t && echo "MIDDLE-NOT: placeholder2" >>%t && echo "TRAILING-NOT: placeholder3" >>%t && \
+; RUN: %ProtectFileCheckOutput not FileCheck --strict-whitespace --check-prefixes LEADING,MIDDLE,TRAILING --dump-input=never --input-file  %t %t 2>&1 | \
+; RUN: FileCheck --check-prefix TEST4 %s
+
+; TEST1:           error: MIDDLE-NOT: excluded string found in input
+; TEST1-NEXT:      MIDDLE-NOT: placeholder2
+; TEST1-NEXT: {{^}}            ^{{$}}
+; TEST1-NEXT:      note: found here
+; TEST1-NEXT:      MIDDLE-NOT: placeholder2
+; TEST1-NEXT: {{^}}            ^~~~~~~~~~~~{{$}}
+; TEST1-NEXT:      error: TRAILING-NOT: excluded string found in input
+; TEST1-NEXT:      TRAILING-NOT: placeholder3
+; TEST1-NEXT: {{^}}              ^{{$}}
+; TEST1-NEXT:      note: found here
+; TEST1-NEXT:      TRAILING-NOT: placeholder3
+; TEST1-NEXT: {{^}}              ^~~~~~~~~~~~{{$}}
+
+; TEST2:           error: MIDDLE-NOT: excluded string found in input
+; TEST2-NEXT:      MIDDLE-NOT: placeholder2
+; TEST2-NEXT: {{^}}            ^{{$}}
+; TEST2-NEXT:      note: found here
+; TEST2-NEXT:      MIDDLE-NOT: placeholder2
+; TEST2-NEXT: {{^}}            ^~~~~~~~~~~~{{$}}
+
+; TEST3:           error: LEADING-NOT: excluded string found in input
+; TEST3-NEXT:      LEADING-NOT: placeholder1
+; TEST3-NEXT: {{^}}            ^{{$}}
+; TEST3-NEXT:      note: found here
+; TEST3-NEXT:      LEADING-NOT: placeholder1
+; TEST3-NEXT: {{^}}            ^~~~~~~~~~~~{{$}}
+
+; TEST4:           error: LEADING-NOT: excluded string found in input
+; TEST4-NEXT:      LEADING-NOT: placeholder1
+; TEST4-NEXT: {{^}}            ^{{$}}
+; TEST4-NEXT:      note: found here
+; TEST4-NEXT:      LEADING-NOT: placeholder1
+; TEST4-NEXT: {{^}}            ^~~~~~~~~~~~{{$}}
+; TEST4-NEXT:      error: MIDDLE-NOT: excluded string found in input
+; TEST4-NEXT:      MIDDLE-NOT: placeholder2
+; TEST4-NEXT: {{^}}            ^{{$}}
+; TEST4-NEXT:      note: found here
+; TEST4-NEXT:      MIDDLE-NOT: placeholder2
+; TEST4-NEXT: {{^}}            ^~~~~~~~~~~~{{$}}
+; TEST4-NEXT:      error: TRAILING-NOT: excluded string found in input
+; TEST4-NEXT:      TRAILING-NOT: placeholder3
+; TEST4-NEXT: {{^}}              ^{{$}}
+; TEST4-NEXT:      note: found here
+; TEST4-NEXT:      TRAILING-NOT: placeholder3
+; TEST4-NEXT: {{^}}              ^~~~~~~~~~~~{{$}}
diff --git a/llvm/test/FileCheck/dump-input/annotations.txt b/llvm/test/FileCheck/dump-input/annotations.txt
index 45bf546..367ea33 100644
--- a/llvm/test/FileCheck/dump-input/annotations.txt
+++ b/llvm/test/FileCheck/dump-input/annotations.txt
@@ -650,7 +650,7 @@
 ; RUN:             -implicit-check-not='{{remark:|error:}}'
 
 ; Verbose diagnostics are suppressed but not errors.
-; IMPNOT:{{.*}}command line:1:22: error: CHECK-NOT: excluded string found in input
+; IMPNOT:{{.*}}command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 
 ;         IMPNOT:<<<<<<
 ;    IMPNOT-NEXT:            1: hello world again! 
diff --git a/llvm/test/FileCheck/implicit-check-not.txt b/llvm/test/FileCheck/implicit-check-not.txt
index 95dd9fa..eaca0d3 100644
--- a/llvm/test/FileCheck/implicit-check-not.txt
+++ b/llvm/test/FileCheck/implicit-check-not.txt
@@ -21,26 +21,26 @@
 
 warning: aaa
 ; CHECK-PASS: warning: aaa
-; CHECK-ERROR1: command line:1:22: error: CHECK-FAIL1-NOT: excluded string found in input
+; CHECK-ERROR1: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR1-NEXT: -implicit-check-not='warning:'
 ; CHECK-ERROR1: note: found here
 ; CHECK-FAIL2: warning: aaa
 ; CHECK-FAIL3: warning: aaa
-; CHECK-ERROR4: command line:1:22: error: CHECK-FAIL1-NOT: excluded string found in input
+; CHECK-ERROR4: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR4-NEXT: {{-implicit-check-not='\{\{aaa\|bbb\|ccc\}\}'}}
 ; CHECK-ERROR4: note: found here
-; CHECK-ERROR5: command line:1:22: error: CHECK-FAIL1-NOT: excluded string found in input
+; CHECK-ERROR5: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR5-NEXT: -implicit-check-not='aaa'
 ; CHECK-ERROR5: note: found here
 
 warning: bbb
 ; CHECK-PASS: warning: bbb
 ; CHECK-FAIL1: warning: bbb
-; CHECK-ERROR2: command line:1:22: error: CHECK-FAIL2-NOT: excluded string found in input
+; CHECK-ERROR2: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR2-NEXT: -implicit-check-not='warning:'
 ; CHECK-ERROR2: note: found here
 ; CHECK-FAIL3: warning: bbb
-; CHECK-ERROR6: command line:1:22: error: CHECK-FAIL2-NOT: excluded string found in input
+; CHECK-ERROR6: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR6-NEXT: -implicit-check-not='bbb'
 ; CHECK-ERROR6: note: found here
 
@@ -48,9 +48,9 @@ warning: ccc
 ; CHECK-PASS: warning: ccc
 ; CHECK-FAIL1: warning: ccc
 ; CHECK-FAIL2: warning: ccc
-; CHECK-ERROR3: command line:1:22: error: CHECK-FAIL3-NOT: excluded string found in input
+; CHECK-ERROR3: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR3-NEXT: -implicit-check-not='warning:'
 ; CHECK-ERROR3: note: found here
-; CHECK-ERROR7: command line:1:22: error: CHECK-FAIL3-NOT: excluded string found in input
+; CHECK-ERROR7: command line:1:22: error: IMPLICIT-CHECK-NOT: excluded string found in input
 ; CHECK-ERROR7-NEXT: -implicit-check-not='ccc'
 ; CHECK-ERROR7: note: found here