Fix #10720 Hang/Crash with big variadic template

Makefile

@@ -805,7 +805,7 @@ test/testsimplifytokens.o: test/testsimplifytokens.cpp lib/check.h lib/color.h l
 test/testsimplifytypedef.o: test/testsimplifytypedef.cpp externals/simplecpp/simplecpp.h lib/check.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h
 	$(CXX) ${INCLUDE_FOR_TEST} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ test/testsimplifytypedef.cpp
 
-test/testsimplifyusing.o: test/testsimplifyusing.cpp lib/check.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h
+test/testsimplifyusing.o: test/testsimplifyusing.cpp externals/simplecpp/simplecpp.h lib/check.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h
 	$(CXX) ${INCLUDE_FOR_TEST} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ test/testsimplifyusing.cpp
 
 test/testsingleexecutor.o: test/testsingleexecutor.cpp cli/executor.h cli/singleexecutor.h lib/analyzerinfo.h lib/check.h lib/color.h lib/config.h lib/cppcheck.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/timer.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h test/helpers.h test/redirect.h

lib/tokenize.cpp

@@ -2760,11 +2760,23 @@ static bool scopesMatch(const std::string &scope1, const std::string &scope2, co
     return false;
 }
 
+static unsigned int tokDistance(const Token* tok1, const Token* tok2) {
+    unsigned int dist = 0;
+    const Token* tok = tok1;
+    while (tok != tok2) {
+        ++dist;
+        tok = tok->next();
+    }
+    return dist;
+};
+
 bool Tokenizer::simplifyUsing()
 {
     if (!isCPP() || mSettings->standards.cpp < Standards::CPP11)
         return false;
 
+    const unsigned int maxReplacementTokens = 1000; // limit the number of tokens we replace
+
     bool substitute = false;
     ScopeInfo3 scopeInfo;
     ScopeInfo3 *currentScope = &scopeInfo;
@@ -3006,6 +3018,12 @@ bool Tokenizer::simplifyUsing()
             } else if (!usingMatch(nameToken, scope, &tok1, scope1, currentScope1, nullptr))
                 continue;
 
+            const auto nReplace = tokDistance(start, usingEnd);
+            if (nReplace > maxReplacementTokens) {
+                simplifyUsingError(usingStart, usingEnd);
+                continue;
+            }
+
             // remove the qualification
             std::string fullScope = scope;
             std::string removed;
@@ -3187,18 +3205,7 @@ bool Tokenizer::simplifyUsing()
                 }
             } else {
                 skip = true;
-                if (mSettings->debugwarnings && mErrorLogger) {
-                    std::string str;
-                    for (Token *tok3 = usingStart; tok3 && tok3 != usingEnd; tok3 = tok3->next()) {
-                        if (!str.empty())
-                            str += ' ';
-                        str += tok3->str();
-                    }
-                    str += " ;";
-                    std::list<const Token *> callstack(1, usingStart);
-                    mErrorLogger->reportErr(ErrorMessage(callstack, &list, Severity::debug, "simplifyUsing",
-                                                         "Failed to parse \'" + str + "\'. The checking continues anyway.", Certainty::normal));
-                }
+                simplifyUsingError(usingStart, usingEnd);
             }
             tok1 = after;
         }
@@ -3233,6 +3240,22 @@ bool Tokenizer::simplifyUsing()
     return substitute;
 }
 
+void Tokenizer::simplifyUsingError(const Token* usingStart, const Token* usingEnd)
+{
+    if (mSettings->debugwarnings && mErrorLogger) {
+        std::string str;
+        for (const Token *tok = usingStart; tok && tok != usingEnd; tok = tok->next()) {
+            if (!str.empty())
+                str += ' ';
+            str += tok->str();
+        }
+        str += " ;";
+        std::list<const Token *> callstack(1, usingStart);
+        mErrorLogger->reportErr(ErrorMessage(callstack, &list, Severity::debug, "simplifyUsing",
+                                             "Failed to parse \'" + str + "\'. The checking continues anyway.", Certainty::normal));
+    }
+}
+
 bool Tokenizer::createTokens(std::istream &code,
                              const std::string& FileName)
 {

lib/tokenize.h

@@ -280,6 +280,7 @@ class CPPCHECKLIB Tokenizer {
     /**
      */
     bool simplifyUsing();
+    void simplifyUsingError(const Token* usingStart, const Token* usingEnd);
 
     /** Simplify useless C++ empty namespaces, like: 'namespace %name% { }'*/
     void simplifyEmptyNamespaces();

test/testsimplifyusing.cpp

@@ -24,6 +24,8 @@
 #include "token.h"
 #include "tokenize.h"
 
+#include <simplecpp.h>
+
 #include <sstream> // IWYU pragma: keep
 #include <string>
 
@@ -92,20 +94,33 @@ class TestSimplifyUsing : public TestFixture {
         TEST_CASE(simplifyUsing10172);
         TEST_CASE(simplifyUsing10173);
         TEST_CASE(simplifyUsing10335);
+        TEST_CASE(simplifyUsing10720);
 
         TEST_CASE(scopeInfo1);
         TEST_CASE(scopeInfo2);
     }
 
 #define tok(...) tok_(__FILE__, __LINE__, __VA_ARGS__)
-    std::string tok_(const char* file, int line, const char code[], cppcheck::Platform::Type type = cppcheck::Platform::Type::Native, bool debugwarnings = true) {
+    std::string tok_(const char* file, int line, const char code[], cppcheck::Platform::Type type = cppcheck::Platform::Type::Native, bool debugwarnings = true, bool preprocess = false) {
         errout.str("");
 
         settings0.certainty.enable(Certainty::inconclusive);
         settings0.debugwarnings = debugwarnings;
         PLATFORM(settings0.platform, type);
         Tokenizer tokenizer(&settings0, this);
 
+        if (preprocess) {
+            std::vector<std::string> files{ "test.cpp" };
+            std::istringstream istr(code);
+            const simplecpp::TokenList tokens1(istr, files, files[0]);
+
+            simplecpp::TokenList tokens2(files);
+            std::map<std::string, simplecpp::TokenList*> filedata;
+            simplecpp::preprocess(tokens2, tokens1, files, filedata, simplecpp::DUI());
+
+            tokenizer.createTokens(std::move(tokens2));
+        }
+
         std::istringstream istr(code);
         ASSERT_LOC(tokenizer.tokenize(istr, "test.cpp"), file, line);
 
@@ -1346,6 +1361,17 @@ class TestSimplifyUsing : public TestFixture {
         ASSERT_EQUALS(exp, tok(code));
     }
 
+    void simplifyUsing10720() {
+        const char code[] = "template <typename... Ts>\n"
+                            "struct S {};\n"
+                            "#define STAMP(thiz, prev) using thiz = S<prev, prev, prev, prev, prev, prev, prev, prev, prev, prev>;\n"
+                            "STAMP(A, int);\n"
+                            "STAMP(B, A);\n"
+                            "STAMP(C, B);\n";
+        tok(code, cppcheck::Platform::Type::Native, /*debugwarnings*/ true, /*preprocess*/ true);
+        ASSERT_EQUALS(errout.str().compare(0, 64, "[test.cpp:6]: (debug) Failed to parse 'using C = S < S < S < int"), 0);
+    }
+
     void scopeInfo1() {
         const char code[] = "struct A {\n"
                             "    enum class Mode { UNKNOWN, ENABLED, NONE, };\n"