[clang-format] distinguish multiplication after brace-init from pointer

[krasimir]

Summary

After https://github.com/llvm/llvm-project/commit/b646f0955574c6ad4c156c9db522e46f597cfda9,
the added regression test started being formatted as-if the
multiplication * was a pointer. This adapts the heuristic to
distinguish between these two cases.

[jackhong12]

I think we can also add new test cases in clang/unittests/Format/TokenAnnotatorTest.cpp.

Tokens = annotate("int i = int{42} * 34;");
...

[owenpan]

clang/lib/Format/TokenAnnotator.cpp

2328

[krasimir]

• address review comments

[krasimir]

In D129771#3653830, @jackhong12 wrote:

I think we can also add new test cases in clang/unittests/Format/TokenAnnotatorTest.cpp.

Tokens = annotate("int i = int{42} * 34;");
...

added a test.

[jackhong12]

This comment was removed by jackhong12.

clang/lib/Format/TokenAnnotator.cpp

TokenType determineStarAmpUsage(const FormatToken &Tok, bool IsExpression,
     if (NextToken->is(tok::kw_operator) && !IsExpression)
       return TT_PointerOrReference;
     if (NextToken->isOneOf(tok::comma, tok::semi))
       return TT_PointerOrReference;
 
     // After right braces, star tokens are likely to be pointers to struct,
     // union, or class.
     //   struct {} *ptr;
-    if (PrevToken->is(tok::r_brace) && Tok.is(tok::star))
+    // This by itself is not sufficient to distinguish from multiplication
+    // following a brace-initialized expression, as in:
+    // int i = int{42} * 2;
+    // In the struct case, the part of the struct declaration until the `{` and
+    // the `}` are put on separate unwrapped lines; in the brace-initialized
+    // case, the matching `{` is on the same unwrapped line, so check for the
+    // presence of the matching brace to distinguish between those.
+    if (PrevToken->is(tok::r_brace) && Tok.is(tok::star) &&
+        !PrevToken->MatchingParen)
       return TT_PointerOrReference;
 
     // For "} &&"
     if (PrevToken->is(tok::r_brace) && Tok.is(tok::ampamp)) {
       const FormatToken *MatchingLBrace = PrevToken->MatchingParen;
 
       // We check whether there is a TemplateCloser(">") to indicate it's a
       // template or not. If it's not a template, "&&" is likely a reference

clang/unittests/Format/FormatTest.cpp

verifyFormat("struct {\n"
                "}* ptr;",
                Style);
   verifyFormat("union {\n"
                "}* ptr;",
                Style);
   verifyFormat("class {\n"
                "}* ptr;",
                Style);
+  // Don't confuse a multiplication after a brace-initialized expression with
+  // a class pointer.
+  verifyFormat("int i = int{42} * 34;", Style);
   verifyFormat("struct {\n"
                "}&& ptr = {};",
                Style);
   verifyFormat("union {\n"
                "}&& ptr = {};",
                Style);
   verifyFormat("class {\n"
                "}&& ptr = {};",

clang/unittests/Format/TokenAnnotatorTest.cpp

TEST_F(TokenAnnotatorTest, UnderstandsUsesOfStarAndAmp) {
   Tokens = annotate("union {\n"
                     "} &&ptr = {};");
   EXPECT_EQ(Tokens.size(), 10u) << Tokens;
   EXPECT_TOKEN(Tokens[3], tok::ampamp, TT_PointerOrReference);
   Tokens = annotate("class {\n"
                     "} &&ptr = {};");
   EXPECT_EQ(Tokens.size(), 10u) << Tokens;
   EXPECT_TOKEN(Tokens[3], tok::ampamp, TT_PointerOrReference);
+  Tokens = annotate("int i = int{42} * 2;");
+  EXPECT_EQ(Tokens.size(), 11u) << Tokens;
+  EXPECT_TOKEN(Tokens[7], tok::star, TT_BinaryOperator);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsUsesOfPlusAndMinus) {
   auto Tokens = annotate("x - 0");
   ASSERT_EQ(Tokens.size(), 4u) << Tokens;
   EXPECT_TOKEN(Tokens[1], tok::minus, TT_BinaryOperator);
   Tokens = annotate("0 + 0");
   ASSERT_EQ(Tokens.size(), 4u) << Tokens;