fix #10081 (Hang: TemplateSimplifier::useDefaultArgumentValues) (#3021)

Author: IOBYTE

lib/templatesimplifier.cpp

@@ -985,7 +985,11 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
     // template parameters with default value has syntax such as:
     //     x = y
     // this list will contain all the '=' tokens for such arguments
-    std::list<Token *> eq;
+    struct Default {
+        Token *eq;
+        Token *end;
+    };
+    std::list<Default> eq;
     // and this set the position of parameters with a default value
     std::set<std::size_t> defaultedArgPos;
 
@@ -1012,9 +1016,11 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
 
         // end of template parameters?
         if (tok->str() == ">") {
-            if (templateParmDepth<2)
+            if (templateParmDepth<2) {
+                if (!eq.empty())
+                    eq.back().end = tok;
                 break;
-            else
+            } else
                 --templateParmDepth;
         }
 
@@ -1023,13 +1029,16 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
             typeParameterNames[tok->strAt(1)] = templatepar - 1;
 
         // next template parameter
-        if (tok->str() == "," && (1 == templateParmDepth)) // Ticket #5823: Properly count parameters
+        if (tok->str() == "," && (1 == templateParmDepth)) { // Ticket #5823: Properly count parameters
+            if (!eq.empty())
+                eq.back().end = tok;
             ++templatepar;
+        }
 
         // default parameter value?
         else if (Token::Match(tok, "= !!>")) {
             if (defaultedArgPos.insert(templatepar).second) {
-                eq.push_back(tok);
+                eq.push_back(Default{tok, nullptr});
             } else {
                 // Ticket #5605: Syntax error (two equal signs for the same parameter), bail out
                 eq.clear();
@@ -1085,25 +1094,30 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
 
         if (tok && tok->str() == ">") {
             tok = tok->previous();
-            std::list<Token *>::const_iterator it = eq.begin();
+            std::list<Default>::const_iterator it = eq.begin();
             for (std::size_t i = (templatepar - eq.size()); it != eq.end() && i < usedpar; ++i)
                 ++it;
             int count = 0;
             while (it != eq.end()) {
-                int indentlevel = 0;
+                // check for end
+                if (!it->end) {
+                    if (mSettings->debugwarnings) {
+                        const std::list<const Token*> locationList(1, it->eq);
+                        const ErrorMessage errmsg(locationList, &mTokenizer->list,
+                                                  Severity::debug,
+                                                  "noparamend",
+                                                  "TemplateSimplifier couldn't find end of template parameter.",
+                                                  false);
+                    }
+                    break;
+                }
+
                 if ((usedpar + count) && usedpar <= (instantiationArgs.size() + count)) {
                     tok->insertToken(",");
                     tok = tok->next();
                 }
-                const Token *from = (*it)->next();
                 std::stack<Token *> links;
-                while (from && (!links.empty() || indentlevel || !Token::Match(from, ",|>"))) {
-                    if (from->str() == "<" &&
-                        (from->strAt(1) == ">" || (from->previous()->isName() &&
-                                                   typeParameterNames.find(from->strAt(-1)) == typeParameterNames.end())))
-                        ++indentlevel;
-                    else if (from->str() == ">" && (links.empty() || links.top()->str() == "<" || indentlevel))
-                        --indentlevel;
+                for (const Token* from = it->eq->next(); from && from != it->end; from = from->next()) {
                     auto entry = typeParameterNames.find(from->str());
                     if (entry != typeParameterNames.end() && entry->second < instantiationArgs.size()) {
                         for (const Token *tok1 : instantiationArgs[entry->second]) {
@@ -1128,7 +1142,6 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
                             links.pop();
                         }
                     }
-                    from = from->next();
                 }
                 ++it;
                 count++;
@@ -1139,7 +1152,8 @@ void TemplateSimplifier::useDefaultArgumentValues(TokenAndName &declaration)
         simplifyTemplateArgs(instantiation.token()->next(), instantiationEnd);
     }
 
-    for (Token * const eqtok : eq) {
+    for (const auto & entry : eq) {
+        Token *const eqtok = entry.eq;
         Token *tok2;
         int indentlevel = 0;
         for (tok2 = eqtok->next(); tok2; tok2 = tok2->next()) {

test/testsimplifytemplate.cpp

@@ -208,6 +208,7 @@ class TestSimplifyTemplate : public TestFixture {
         TEST_CASE(template163); // #9685 syntax error
         TEST_CASE(template164); // #9394
         TEST_CASE(template165); // #10032 syntax error
+        TEST_CASE(template166); // #10081 hang
         TEST_CASE(template_specialization_1);  // #7868 - template specialization template <typename T> struct S<C<T>> {..};
         TEST_CASE(template_specialization_2);  // #7868 - template specialization template <typename T> struct S<C<T>> {..};
         TEST_CASE(template_enum);  // #6299 Syntax error in complex enum declaration (including template)
@@ -4178,6 +4179,16 @@ class TestSimplifyTemplate : public TestFixture {
         ASSERT_EQUALS(exp, tok(code));
     }
 
+    void template166() { // #10081 hang
+        const char code[] = "template <typename T, size_t k = (T::s < 3) ? 0 : 3>\n"
+                            "void foo() {}\n"
+                            "foo<T>();";
+        const char exp[]  = "void foo<T,(T::s<3)?0:3> ( ) ; "
+                            "foo<T,(T::s<3)?0:3> ( ) ; "
+                            "void foo<T,(T::s<3)?0:3> ( ) { }";
+        ASSERT_EQUALS(exp, tok(code));
+    }
+
     void template_specialization_1() {  // #7868 - template specialization template <typename T> struct S<C<T>> {..};
         const char code[] = "template <typename T> struct C {};\n"
                             "template <typename T> struct S {a};\n"