From 5efb23ffff8f395802ce63258248ce84961d2723 Mon Sep 17 00:00:00 2001
From: IOBYTE <reif@earthlink.net>
Date: Thu, 23 May 2019 14:53:26 -0400
Subject: [PATCH]  template simplifier: fix instantiation of variadic template
 with no arguments (#1848)

* template simplifier: fix instantiation of variadic template with no arguments

* fix white space change

* add support for <class...>

* add variadic template flag
---
 lib/templatesimplifier.cpp    | 11 +++++++++--
 lib/templatesimplifier.h      |  8 ++++++++
 test/testsimplifytemplate.cpp | 11 +++++++++++
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/lib/templatesimplifier.cpp b/lib/templatesimplifier.cpp
index ef232d5d3..fb3cafd69 100644
--- a/lib/templatesimplifier.cpp
+++ b/lib/templatesimplifier.cpp
@@ -82,6 +82,10 @@ TemplateSimplifier::TokenAndName::TokenAndName(Token *tok, const std::string &s,
         isPartialSpecialization(!isSpecialization() && nameToken->strAt(1) == "<");
         isAlias(paramEnd->strAt(1) == "using");
         isClass(Token::Match(paramEnd->next(), "class|struct|union %name% <|{|:|;"));
+        if (token->strAt(1) == "<" && !isSpecialization()) {
+            const Token *end = token->next()->findClosingBracket();
+            isVariadic(end && Token::findmatch(token->tokAt(2), "typename|class . . .", end));
+        }
         const Token *tok1 = nameToken->next();
         if (tok1->str() == "<") {
             const Token *closing = tok1->findClosingBracket();
@@ -2538,7 +2542,8 @@ bool TemplateSimplifier::simplifyTemplateInstantiations(
         std::list<std::string> typeStringsUsedInTemplateInstantiation;
         std::string typeForNewName = getNewName(tok2, typeStringsUsedInTemplateInstantiation);
 
-        if (typeForNewName.empty() || (!typeParametersInDeclaration.empty() && typeParametersInDeclaration.size() != mTypesUsedInTemplateInstantiation.size())) {
+        if ((typeForNewName.empty() && !templateDeclaration.isVariadic()) ||
+            (!typeParametersInDeclaration.empty() && typeParametersInDeclaration.size() != mTypesUsedInTemplateInstantiation.size())) {
             if (printDebug && mErrorLogger) {
                 std::list<const Token *> callstack(1, tok2);
                 mErrorLogger->reportErr(ErrorLogger::ErrorMessage(callstack, &mTokenList, Severity::debug, "debug",
@@ -2681,7 +2686,7 @@ void TemplateSimplifier::replaceTemplateUsage(
 
         // match parameters
         Token * tok2 = nameTok->tokAt(2);
-        unsigned int typeCountInInstantiation = 1U; // There is always at least one type
+        unsigned int typeCountInInstantiation = tok2->str() == ">" ? 0U : 1U;
         const Token *typetok = (!mTypesUsedInTemplateInstantiation.empty()) ? mTypesUsedInTemplateInstantiation[0].token : nullptr;
         unsigned int indentlevel2 = 0;  // indentlevel for tokgt
         while (tok2 && (indentlevel2 > 0 || tok2->str() != ">")) {
@@ -2895,6 +2900,8 @@ void TemplateSimplifier::printOut(const TokenAndName &tokenAndName, const std::s
         std::cout << " isPartialSpecialization";
     if (tokenAndName.isForwardDeclaration())
         std::cout << " isForwardDeclaration";
+    if (tokenAndName.isVariadic())
+        std::cout << " isVariadic";
     std::cout << std::endl;
     if (tokenAndName.token && !tokenAndName.paramEnd && tokenAndName.token->strAt(1) == "<") {
         const Token *end = tokenAndName.token->next()->findClosingBracket();
diff --git a/lib/templatesimplifier.h b/lib/templatesimplifier.h
index ad2c7e9aa..19e7260d8 100644
--- a/lib/templatesimplifier.h
+++ b/lib/templatesimplifier.h
@@ -106,6 +106,7 @@ public:
             fIsSpecialization        = (1 << 4), // user specialized template
             fIsPartialSpecialization = (1 << 5), // user partial specialized template
             fIsForwardDeclaration    = (1 << 6), // forward declaration
+            fIsVariadic              = (1 << 7), // variadic template
         };
 
         bool isClass() const {
@@ -157,6 +158,13 @@ public:
             setFlag(fIsForwardDeclaration, state);
         }
 
+        bool isVariadic() const {
+            return getFlag(fIsVariadic);
+        }
+        void isVariadic(bool state) {
+            setFlag(fIsVariadic, state);
+        }
+
         /**
          * Get specified flag state.
          * @param flag flag to get state of
diff --git a/test/testsimplifytemplate.cpp b/test/testsimplifytemplate.cpp
index e3bf11991..4d98107ca 100644
--- a/test/testsimplifytemplate.cpp
+++ b/test/testsimplifytemplate.cpp
@@ -191,6 +191,8 @@ private:
         TEST_CASE(templateTypeDeduction2);
 
         TEST_CASE(simplifyTemplateArgs);
+
+        TEST_CASE(template_variadic_1); // #9144
     }
 
     std::string tok(const char code[], bool debugwarnings = false, Settings::PlatformType type = Settings::Native) {
@@ -3618,6 +3620,15 @@ private:
         ASSERT_EQUALS("foo<false> = false ; foo<false> ;", tok("template<bool N> foo = N; foo < ( 1 - 1) ? true : false >;"));
     }
 
+    void template_variadic_1() { // #9144
+        const char code[] = "template <typename...> struct e {};\n"
+                            "static_assert(sizeof(e<>) == sizeof(e<int,int>), \"\");";
+        const char expected[] = "struct e<> ; struct e<int,int> ; "
+                                "static_assert ( sizeof ( e<> ) == sizeof ( e<int,int> ) , \"\" ) ; "
+                                "struct e<> { } ; struct e<int,int> { } ;";
+        ASSERT_EQUALS(expected, tok(code));
+    }
+
 };
 
 REGISTER_TEST(TestSimplifyTemplate)