[analyzer][tests] Fix issue comparison script

When newer build has duplicate issues the script tried to
remove it from the list more than once.  The new approach
changes the way we filter out matching issues.

Differential Revision: https://reviews.llvm.org/D96611

Author: SavchenkoValeriy

clang/utils/analyzer/CmpRuns.py

@@ -36,7 +36,7 @@
 from copy import copy
 from enum import Enum
 from typing import (Any, DefaultDict, Dict, List, NamedTuple, Optional,
-                    Sequence, TextIO, TypeVar, Tuple, Union)
+                    Sequence, Set, TextIO, TypeVar, Tuple, Union)
 
 
 Number = Union[int, float]
@@ -374,8 +374,9 @@ def compare_results(results_old: AnalysisRun, results_new: AnalysisRun,
 
         # Quadratic algorithms in this part are fine because 'old' and 'new'
         # are most commonly of size 1.
-        for a in copy(old):
-            for b in copy(new):
+        common: Set[AnalysisDiagnostic] = set()
+        for a in old:
+            for b in new:
                 if a.get_issue_identifier() == b.get_issue_identifier():
                     a_path_len = a.get_path_length()
                     b_path_len = b.get_path_length()
@@ -394,16 +395,22 @@ def compare_results(results_old: AnalysisRun, results_new: AnalysisRun,
                             path_difference_data.append(
                                 a_path_len - b_path_len)
 
-                    res.add_common(a)
-                    old.remove(a)
-                    new.remove(b)
+                    res.add_common(b)
+                    common.add(a)
+
+        old = filter_issues(old, common)
+        new = filter_issues(new, common)
+        common = set()
 
-        for a in copy(old):
-            for b in copy(new):
+        for a in old:
+            for b in new:
                 if a.is_similar_to(b):
                     res.add_changed(a, b)
-                    old.remove(a)
-                    new.remove(b)
+                    common.add(a)
+                    common.add(b)
+
+        old = filter_issues(old, common)
+        new = filter_issues(new, common)
 
         # Whatever is left in 'old' doesn't have a corresponding diagnostic
         # in 'new', so we need to mark it as 'removed'.
@@ -443,6 +450,12 @@ def compare_results(results_old: AnalysisRun, results_new: AnalysisRun,
     return res
 
 
+def filter_issues(origin: List[AnalysisDiagnostic],
+                  to_remove: Set[AnalysisDiagnostic]) \
+                  -> List[AnalysisDiagnostic]:
+    return [diag for diag in origin if diag not in to_remove]
+
+
 def compute_percentile(values: Sequence[T], percentile: float) -> T:
     """
     Return computed percentile.