clang-format: Allow ternary expressions inside template parameters if

the template parameters aren't inside an expression context.

This fixes llvm.org/PR23270.

llvm-svn: 236603

clang/lib/Format/TokenAnnotator.cpp

@@ -47,6 +47,11 @@ private:
     FormatToken *Left = CurrentToken->Previous;
     Left->ParentBracket = Contexts.back().ContextKind;
     ScopedContextCreator ContextCreator(*this, tok::less, 10);
+
+    // If this angle is in the context of an expression, we need to be more
+    // hesitant to detect it as opening template parameters. 
+    bool InExprContext = Contexts.back().IsExpression;
+
     Contexts.back().IsExpression = false;
     // If there's a template keyword before the opening angle bracket, this is a
     // template parameter, not an argument.
@@ -70,8 +75,8 @@ private:
         next();
         continue;
       }
-      if (CurrentToken->isOneOf(tok::r_paren, tok::r_square, tok::r_brace,
-                                tok::colon, tok::question))
+      if (CurrentToken->isOneOf(tok::r_paren, tok::r_square, tok::r_brace) ||
+          (CurrentToken->isOneOf(tok::colon, tok::question) && InExprContext))
         return false;
       // If a && or || is found and interpreted as a binary operator, this set
       // of angles is likely part of something like "a < b && c > d". If the

clang/unittests/Format/FormatTest.cpp

@@ -5144,6 +5144,8 @@ TEST_F(FormatTest, UnderstandsTemplateParameters) {
   verifyFormat("f<int>();");
   verifyFormat("template <typename T> void f() {}");
   verifyFormat("struct A<std::enable_if<sizeof(T2) < sizeof(int32)>::type>;");
+  verifyFormat("struct A<std::enable_if<sizeof(T2) ? sizeof(int32) : "
+               "sizeof(char)>::type>;");
 
   // Not template parameters.
   verifyFormat("return a < b && c > d;");