From 661ebd3a961a1ad19b01a1237800e7be5407caf5 Mon Sep 17 00:00:00 2001
From: dummyunit <dummyunit@gmail.com>
Date: Mon, 3 May 2021 22:40:49 +0300
Subject: [PATCH] Fix AST for brace initialization after decltype() (#3245)

Currently sub-expressions like decltype(x){} break AST creation for
subsequent tokens in the whole expression. In some cases this triggers
validation checks in validateAst() and analysis on the file stops.
For example, code like this:
    int x = decltype(0){} ? 0 : 1;
currently produces internalAstError.

To fix the issue iscpp11init_impl() was changed to recognize { preceded
by decltype(expr) as a start of C++11 brace initialization expression.
---
 lib/tokenlist.cpp     | 2 ++
 test/testtokenize.cpp | 9 +++++++++
 2 files changed, 11 insertions(+)

diff --git a/lib/tokenlist.cpp b/lib/tokenlist.cpp
index bf99f0180..4f5fed93f 100644
--- a/lib/tokenlist.cpp
+++ b/lib/tokenlist.cpp
@@ -651,6 +651,8 @@ static bool iscpp11init_impl(const Token * const tok)
     }
     if (!nameToken)
         return false;
+    if (nameToken->str() == ")" && Token::simpleMatch(nameToken->link()->previous(), "decltype ("))
+        return true;
     if (nameToken->str() == ">" && nameToken->link())
         nameToken = nameToken->link()->previous();
 
diff --git a/test/testtokenize.cpp b/test/testtokenize.cpp
index ebd4db14c..c7ddfd897 100644
--- a/test/testtokenize.cpp
+++ b/test/testtokenize.cpp
@@ -5815,6 +5815,15 @@ private:
         ASSERT_EQUALS("f1{2{,3{,{x,(", testAst("f({{1},{2},{3}},x);"));
         ASSERT_EQUALS("a1{ b2{", testAst("auto a{1}; auto b{2};"));
         ASSERT_EQUALS("var1ab::23,{,{4ab::56,{,{,{", testAst("auto var{{1,a::b{2,3}}, {4,a::b{5,6}}};"));
+
+        // Initialization with decltype(expr) instead of a type
+        ASSERT_EQUALS("decltypex((", testAst("decltype(x)();"));
+        ASSERT_EQUALS("decltypex({", testAst("decltype(x){};"));
+        ASSERT_EQUALS("decltypexy+(yx+(", testAst("decltype(x+y)(y+x);"));
+        ASSERT_EQUALS("decltypexy+(yx+{", testAst("decltype(x+y){y+x};"));
+
+        // Check that decltype(x){} doesn't break AST creation for subsequent tokens.
+        ASSERT_EQUALS("decltypex({01:?", testAst("decltype(x){} ? 0 : 1;"));
     }
 
     void astbrackets() { // []