[analyzer] Increase minimum complexity filter of the CloneChecker.

[teemperor]

Summary

So far we used a value of 10 which was useful for testing but produces many false-positives in real programs. The usual suspicious clones we find seem to be at around a complexity value of 70 and for normal clone-reporting everything above 50 seems to be a valid normal clone for users, so let's just go with 50 for now and set this as the new default value.

This patch also explicitly sets the complexity value for the regression tests as they serve more of a regression testing/debugging purpose and shouldn't really be reported by default in real programs. I'll add more tests that reflect actual found bugs that then need to pass with the default setting in the future.

[NoQ]

We should probably add a test that shows that the current default value of MinimumCloneComplexity is large. Like, test that the positive we're trying to avoid with this patch is indeed gone.

[NoQ]

Hmm, what else remains to be fixed before we should try to deliver CloneChecker to the users (move out of alpha, either on by default or into optin)?

I think we've had this problem with overlapping clones. I just thought that we could also probably fix it by trying to find clones within clones, with smaller complexity, and suppressing the report if our clones are composed of many copies of smaller clones(?)

[teemperor]

• Rebased and updated patch before merging.

cfe/trunk/lib/StaticAnalyzer/Checkers/CloneChecker.cpp

 
 void CloneChecker::checkEndOfTranslationUnit(const TranslationUnitDecl *TU,
                                              AnalysisManager &Mgr,
                                              BugReporter &BR) const {
   // At this point, every statement in the translation unit has been analyzed by
   // the CloneDetector. The only thing left to do is to report the found clones.
 
   int MinComplexity = Mgr.getAnalyzerOptions().getOptionAsInteger(
-      "MinimumCloneComplexity", 10, this);
+      "MinimumCloneComplexity", 50, this);
   assert(MinComplexity >= 0);
 
   bool ReportSuspiciousClones = Mgr.getAnalyzerOptions().getBooleanOption(
       "ReportSuspiciousClones", true, this);
 
   bool ReportNormalClones = Mgr.getAnalyzerOptions().getBooleanOption(
       "ReportNormalClones", true, this);
 

cfe/trunk/test/Analysis/copypaste/asm.cpp

-// RUN: %clang_analyze_cc1 -triple x86_64-unknown-linux -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -triple x86_64-unknown-linux -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 int foo1(int src) {
   int dst = src;
   if (src < 100 && src > 0) {
 
     asm ("mov %1, %0\n\t"

cfe/trunk/test/Analysis/copypaste/attributes.cpp

-// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 int foo1(int n) {
   int result = 0;
   switch (n) {
   case 33:
     result += 33;

cfe/trunk/test/Analysis/copypaste/autogenerated_automoc.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:IgnoredFilesPattern="moc_|.*_automoc.cpp" -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -analyzer-config alpha.clone.CloneChecker:IgnoredFilesPattern="moc_|.*_automoc.cpp" -verify %s
 
 // Because files that have `_automoc.' in their names are most likely autogenerated,
 // we suppress copy-paste warnings here.
 
 // expected-no-diagnostics
 
 void f1() {
   int *p1 = new int[1];

cfe/trunk/test/Analysis/copypaste/blocks.cpp

-// RUN: %clang_analyze_cc1 -fblocks -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -fblocks -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // This tests if we search for clones in blocks.
 
 void log();
 
 auto BlockA = ^(int a, int b){ // expected-warning{{Duplicate code detected}}
   log();
   if (a > b)

cfe/trunk/test/Analysis/copypaste/call.cpp

-// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 bool a();
 bool b();
 
 // Calls method a with some extra code to pass the minimum complexity
 bool foo1(int x) {

cfe/trunk/test/Analysis/copypaste/catch.cpp

-// RUN: %clang_analyze_cc1 -fcxx-exceptions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -fcxx-exceptions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 bool foo1(int x) {
   if (x > 0)
     return false;
   else if (x < 0)
     try { x--; } catch (int i) {}

cfe/trunk/test/Analysis/copypaste/delete.cpp

-// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 bool foo1(int x, int* a) {
   if (x > 0)
     return false;
   else if (x < 0)
     delete a;

cfe/trunk/test/Analysis/copypaste/dependent-exist.cpp

-// RUN: %clang_analyze_cc1 -fms-extensions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -fms-extensions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 bool foo1(int x) {
   if (x < 0) {
     __if_exists(x) { return false; }
   }
   return true;

cfe/trunk/test/Analysis/copypaste/expr-types.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 
 int foo1(int a, int b) {
   if (a > b)
     return a;
   return b;
 }
 
 // Different types, so not a clone
 int foo2(long a, long b) {
   if (a > b)
     return a;
   return b;
 }

cfe/trunk/test/Analysis/copypaste/fold.cpp

-// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 int global = 0;
 
 template<typename ...Args>
 int foo1(Args&&... args) {
   if (global > 0)

cfe/trunk/test/Analysis/copypaste/function-try-block.cpp

-// RUN: %clang_analyze_cc1 -fcxx-exceptions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -fcxx-exceptions -std=c++1z -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // Tests if function try blocks are correctly handled.
 
 void nonCompoundStmt1(int& x)
   try { x += 1; } catch(...) { x -= 1; } // expected-warning{{Duplicate code detected}}
 
 void nonCompoundStmt2(int& x)
   try { x += 1; } catch(...) { x -= 1; } // expected-note{{Similar code here}}

cfe/trunk/test/Analysis/copypaste/functions.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // This tests if we search for clones in functions.
 
 void log();
 
 int max(int a, int b) { // expected-warning{{Duplicate code detected}}
   log();
   if (a > b)

cfe/trunk/test/Analysis/copypaste/generic.c

-// RUN: %clang_analyze_cc1 -std=c11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 int global;
 
 int foo1() {
   if (global > 0)
     return 0;

cfe/trunk/test/Analysis/copypaste/labels.cpp

-// RUN: %clang_analyze_cc1 -std=gnu++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=gnu++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 
 bool foo1(int x) {
   start:
   if (x != 3) {
     ++x;

cfe/trunk/test/Analysis/copypaste/lambda.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // expected-no-diagnostics
 
 void foo1(int a, long b) {
   auto l = [a, b](){};
 }
 
 void foo2(int a, long b) {

cfe/trunk/test/Analysis/copypaste/macros.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // Tests that macros and non-macro clones aren't mixed into the same hash
 // group. This is currently necessary as all clones in a hash group need
 // to have the same complexity value. Macros have smaller complexity values
 // and need to be in their own hash group.
 
 int foo(int a) { // expected-warning{{Duplicate code detected}}
   a = a + 1;

cfe/trunk/test/Analysis/copypaste/not-autogenerated.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:IgnoredFilesPattern="moc_|ui_|dbus_|.*_automoc" -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -analyzer-config alpha.clone.CloneChecker:IgnoredFilesPattern="moc_|ui_|dbus_|.*_automoc" -verify %s
 
 void f1() {
   int *p1 = new int[1];
   int *p2 = new int[1];
   if (p1) {
     delete [] p1; // expected-note{{Similar code using 'p1' here}}
     p1 = nullptr;
   }
   if (p2) {
     delete [] p1; // expected-warning{{Potential copy-paste error; did you really mean to use 'p1' here?}}
     p2 = nullptr;
   }
 }

cfe/trunk/test/Analysis/copypaste/objc-methods.m

-// RUN: %clang_analyze_cc1 -Wno-objc-root-class -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -Wno-objc-root-class -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // This tests if we search for clones in Objective-C methods.
 
 @interface A
 - (int) setOk : (int) a : (int) b;
 @end
 
 @implementation A

cfe/trunk/test/Analysis/copypaste/plist-diagnostics-notes-as-events.cpp

-// RUN: %clang_analyze_cc1 -analyzer-output=plist -analyzer-config notes-as-events=true -o %t.plist -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-output=plist -analyzer-config notes-as-events=true -o %t.plist -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 // RUN: FileCheck --input-file=%t.plist %s
 
 void log();
 
 int max(int a, int b) { // expected-warning{{Duplicate code detected}}
   log();
   if (a > b)
     return a;

cfe/trunk/test/Analysis/copypaste/plist-diagnostics.cpp

-// RUN: %clang_analyze_cc1 -analyzer-output=plist -o %t.plist -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-output=plist -o %t.plist -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 // RUN: FileCheck --input-file=%t.plist %s
 
 void log();
 
 int max(int a, int b) { // expected-warning{{Duplicate code detected}}
   log();
   if (a > b)
     return a;

cfe/trunk/test/Analysis/copypaste/sub-sequences.cpp

-// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // This tests if sub-sequences can match with normal sequences.
 
 void log2(int a);
 void log();
 
 int max(int a, int b) {
   log2(a);

cfe/trunk/test/Analysis/copypaste/suspicious-clones.cpp

-// RUN: %clang_analyze_cc1 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:ReportSuspiciousClones=true  -analyzer-config alpha.clone.CloneChecker:ReportNormalClones=false -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:ReportSuspiciousClones=true  -analyzer-config alpha.clone.CloneChecker:ReportNormalClones=false -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 // Tests finding a suspicious clone that references local variables.
 
 void log();
 
 int max(int a, int b) {
   log();
   if (a > b)

cfe/trunk/test/Analysis/copypaste/text-diagnostics.cpp

-// RUN: %clang_analyze_cc1 -analyzer-output=text -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -verify %s
+// RUN: %clang_analyze_cc1 -analyzer-output=text -std=c++11 -analyzer-checker=alpha.clone.CloneChecker -analyzer-config alpha.clone.CloneChecker:MinimumCloneComplexity=10 -verify %s
 
 void log();
 
 int max(int a, int b) { // expected-warning{{Duplicate code detected}} // expected-note{{Duplicate code detected}}
   log();
   if (a > b)
     return a;
   return b;
 }
 
 int maxClone(int a, int b) { // expected-note{{Similar code here}}
   log();
   if (a > b)
     return a;
   return b;
 }