From 30cec97cc890d28b39520c906150a66ccb7a3a93 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Sat, 12 Feb 2022 12:19:08 +0100
Subject: [PATCH] Tokenizer: Support C++20 default bit-field member initializer

---
 lib/tokenize.cpp      | 10 ++++++----
 test/testtokenize.cpp | 11 +++++++++++
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index f13917896..f8f28e70e 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -10290,8 +10290,10 @@ void Tokenizer::findGarbageCode() const
             unknownMacroError(tok);
 
         // Assign/increment/decrement literal
-        else if (Token::Match(tok, "!!) %num%|%str%|%char% %assign%|++|--"))
-            syntaxError(tok, tok->next()->str() + " " + tok->strAt(2));
+        else if (Token::Match(tok, "!!) %num%|%str%|%char% %assign%|++|--")) {
+            if (!isCPP() || mSettings->standards.cpp < Standards::CPP20 || !Token::Match(tok->previous(), "%name% : %num% ="))
+                syntaxError(tok, tok->next()->str() + " " + tok->strAt(2));
+        }
 
         if (tok->isControlFlowKeyword() && Token::Match(tok, "if|while|for|switch")) { // if|while|for|switch (EXPR) { ... }
             if (tok->previous() && !Token::Match(tok->previous(), "%name%|:|;|{|}|)")) {
@@ -11566,12 +11568,12 @@ void Tokenizer::simplifyBitfields()
             !Token::Match(tok->next(), "case|public|protected|private|class|struct") &&
             !Token::simpleMatch(tok->tokAt(2), "default :")) {
             Token *tok1 = (tok->next()->str() == "const") ? tok->tokAt(3) : tok->tokAt(2);
-            if (Token::Match(tok1, "%name% : %num% ;"))
+            if (Token::Match(tok1, "%name% : %num% [;=]"))
                 tok1->setBits(MathLib::toLongNumber(tok1->strAt(2)));
             if (tok1 && tok1->tokAt(2) &&
                 (Token::Match(tok1->tokAt(2), "%bool%|%num%") ||
                  !Token::Match(tok1->tokAt(2), "public|protected|private| %type% ::|<|,|{|;"))) {
-                while (tok1->next() && !Token::Match(tok1->next(), "[;,)]{}]")) {
+                while (tok1->next() && !Token::Match(tok1->next(), "[;,)]{}=]")) {
                     if (Token::Match(tok1->next(), "[([]"))
                         Token::eraseTokens(tok1, tok1->next()->link());
                     tok1->deleteNext();
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index d5d8aa1b9..ea6400a43 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -448,6 +448,8 @@ private:
         TEST_CASE(simplifyIfSwitchForInit3);
         TEST_CASE(simplifyIfSwitchForInit4);
         TEST_CASE(simplifyIfSwitchForInit5);
+
+        TEST_CASE(cpp20_default_bitfield_initializer);
     }
 
 #define tokenizeAndStringify(...) tokenizeAndStringify_(__FILE__, __LINE__, __VA_ARGS__)
@@ -7213,6 +7215,15 @@ private:
         const char code[] = "void f() { if ([] { ; }) {} }";
         ASSERT_EQUALS("void f ( ) { if ( [ ] { ; } ) { } }", tokenizeAndStringify(code, settings));
     }
+
+    void cpp20_default_bitfield_initializer() {
+        Settings settings;
+        const char code[] = "struct S { int a:2 = 0; };";
+        settings.standards.cpp = Standards::CPP20;
+        ASSERT_EQUALS("struct S { int a ; a = 0 ; } ;", tokenizeAndStringify(code, settings));
+        settings.standards.cpp = Standards::CPP17;
+        ASSERT_THROW(tokenizeAndStringify(code, settings), InternalError);
+    }
 };
 
 REGISTER_TEST(TestTokenizer)