From c9dc92c26609b98f4b33cf1584266e9e81cfc35b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Marjam=C3=A4ki?= <daniel.marjamaki@gmail.com>
Date: Sat, 24 Apr 2021 11:47:51 +0200
Subject: [PATCH] Parser; C++20 for loop with initialization expression

---
 lib/tokenize.cpp      |  8 ++++++--
 lib/tokenlist.cpp     | 38 ++++++++++++++++++++++----------------
 test/testtokenize.cpp | 15 +++++++++++++--
 3 files changed, 41 insertions(+), 20 deletions(-)

diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 91934ee16..f7a823900 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -10182,9 +10182,10 @@ void Tokenizer::findGarbageCode() const
             }
         }
         // if we have an invalid number of semicolons inside for( ), assume syntax error
-        if ((semicolons == 1) || (semicolons > 2)) {
+        if (semicolons > 2)
+            syntaxError(tok);
+        if (semicolons == 1 && !(isCPP() && mSettings->standards.cpp >= Standards::CPP20))
             syntaxError(tok);
-        }
     }
 
     // Operators without operands..
@@ -11281,6 +11282,9 @@ void Tokenizer::simplifyBitfields()
         }
         Token *last = nullptr;
 
+        if (Token::simpleMatch(tok, "for ("))
+            tok = tok->linkAt(1);
+
         if (!Token::Match(tok, ";|{|}|public:|protected:|private:"))
             continue;
 
diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index 00033f0c1..d9f94b8e8 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -1495,26 +1495,32 @@ static Token * createAstAtToken(Token *tok, bool cpp)
         Token * const semicolon2 = tok2;
         if (!semicolon2)
             return nullptr; // invalid code #7235
-        tok2 = tok2->next();
-        AST_state state3(cpp);
-        if (Token::simpleMatch(tok2, "( {")) {
-            state3.op.push(tok2->next());
-            tok2 = tok2->link()->next();
+
+        if (semicolon2->str() == ";") {
+            tok2 = tok2->next();
+            AST_state state3(cpp);
+            if (Token::simpleMatch(tok2, "( {")) {
+                state3.op.push(tok2->next());
+                tok2 = tok2->link()->next();
+            }
+            compileExpression(tok2, state3);
+
+            tok2 = findAstTop(semicolon1->next(), semicolon2);
+            if (tok2)
+                semicolon2->astOperand1(tok2);
+            tok2 = findAstTop(semicolon2->next(), endPar);
+            if (tok2)
+                semicolon2->astOperand2(tok2);
+            else if (!state3.op.empty())
+                semicolon2->astOperand2(state3.op.top());
+            semicolon1->astOperand2(semicolon2);
+        } else {
+            tok2 = findAstTop(semicolon1->next(), semicolon2);
+            semicolon1->astOperand2(tok2 ? tok2 : state2.op.top());
         }
-        compileExpression(tok2, state3);
 
         if (init != semicolon1)
             semicolon1->astOperand1(init->astTop());
-        tok2 = findAstTop(semicolon1->next(), semicolon2);
-        if (tok2)
-            semicolon2->astOperand1(tok2);
-        tok2 = findAstTop(semicolon2->next(), endPar);
-        if (tok2)
-            semicolon2->astOperand2(tok2);
-        else if (!state3.op.empty())
-            semicolon2->astOperand2(state3.op.top());
-
-        semicolon1->astOperand2(semicolon2);
         tok->next()->astOperand1(tok);
         tok->next()->astOperand2(semicolon1);
 
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index 50fea13e9..fb9ca24d4 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -281,6 +281,7 @@ private:
         TEST_CASE(bitfields14); // ticket #4561 (segfault for 'class a { signals: };')
         TEST_CASE(bitfields15); // ticket #7747 (enum Foo {A,B}:4;)
         TEST_CASE(bitfields16); // Save bitfield bit count
+        TEST_CASE(bitfields17); // for (A; b:c);
 
         TEST_CASE(simplifyNamespaceStd);
 
@@ -3952,6 +3953,13 @@ private:
         ASSERT_EQUALS(1, x->bits());
     }
 
+    void bitfields17() {
+        Settings settings;
+        settings.standards.cpp = Standards::CPP20;
+        const char code[] = "void f() { for (a;b:c) {} }";
+        ASSERT_EQUALS("void f ( ) { for ( a ; b : c ) { } }", tokenizeAndStringify(code, settings));
+    }
+
     void simplifyNamespaceStd() {
         const char *code, *expected;
 
@@ -5366,6 +5374,7 @@ private:
         ASSERT_EQUALS("12*34*5*+", testAst("1*2+3*4*5"));
         ASSERT_EQUALS("0(r.&", testAst("(&((typeof(x))0).r);"));
         ASSERT_EQUALS("0(r.&", testAst("&((typeof(x))0).r;"));
+        ASSERT_EQUALS("0f1(||", testAst("; 0 || f(1);"));
 
         // Various tests of precedence
         ASSERT_EQUALS("ab::c+", testAst("a::b+c"));
@@ -5449,6 +5458,10 @@ private:
         ASSERT_EQUALS("fora*++;;(", testAst("for (++(*a);;);"));
         ASSERT_EQUALS("foryz:(", testAst("for (decltype(x) *y : z);"));
         ASSERT_EQUALS("for(tmpNULL!=tmptmpnext.=;;( tmpa=", testAst("for ( ({ tmp = a; }) ; tmp != NULL; tmp = tmp->next ) {}"));
+        ASSERT_EQUALS("forx0=x;;(", testAst("for (int x=0; x;);"));
+
+        // for with initializer (c++20)
+        ASSERT_EQUALS("forab=ca:;(", testAst("for(a=b;int c:a)"));
 
         // problems with multiple expressions
         ASSERT_EQUALS("ax( whilex(", testAst("a(x) while (x)"));
@@ -5474,9 +5487,7 @@ private:
         // C++17: if (expr1; expr2)
         ASSERT_EQUALS("ifx3=y;(", testAst("if (int x=3; y)"));
 
-        ASSERT_EQUALS("forx0=x;;(", testAst("for (int x=0; x;);"));
 
-        ASSERT_EQUALS("0f1(||", testAst("; 0 || f(1);"));
     }
 
     void astexpr2() { // limit for large expressions