[clang-format] Add spaces around the Verilog implication operator (#7…

…1352)

The Verilog implication operator `->` is a binary operator meaning
either the left hand side is false or the right hand side is true.
Previously it was treated as the C++ struct member operator.

I didn't even know it existed when I added the operator formatting part.
And I didn't check all the tests for all the operators I added. That is
how the bad test got in.

clang/lib/Format/FormatTokenLexer.cpp

@@ -253,7 +253,8 @@ void FormatTokenLexer::tryMergePreviousTokens() {
                           TT_BinaryOperator)) {
       return;
     }
-    // Module paths in specify blocks and implications in properties.
+    // Module paths in specify blocks and the implication and boolean equality
+    // operators.
     if (tryMergeTokensAny({{tok::plusequal, tok::greater},
                            {tok::plus, tok::star, tok::greater},
                            {tok::minusequal, tok::greater},
@@ -265,7 +266,8 @@ void FormatTokenLexer::tryMergePreviousTokens() {
                            {tok::pipe, tok::arrow},
                            {tok::hash, tok::minus, tok::hash},
                            {tok::hash, tok::equal, tok::hash}},
-                          TT_BinaryOperator)) {
+                          TT_BinaryOperator) ||
+        Tokens.back()->is(tok::arrow)) {
       Tokens.back()->ForcedPrecedence = prec::Comma;
       return;
     }

clang/lib/Format/TokenAnnotator.cpp

@@ -2028,6 +2028,9 @@ class AnnotatingParser {
     } else if (Current.is(tok::arrow) &&
                Style.Language == FormatStyle::LK_Java) {
       Current.setType(TT_TrailingReturnArrow);
+    } else if (Current.is(tok::arrow) && Style.isVerilog()) {
+      // The implication operator.
+      Current.setType(TT_BinaryOperator);
     } else if (Current.is(tok::arrow) && AutoFound &&
                Line.MightBeFunctionDecl && Current.NestingLevel == 0 &&
                !Current.Previous->isOneOf(tok::kw_operator, tok::identifier)) {
@@ -4717,6 +4720,9 @@ bool TokenAnnotator::spaceRequiredBefore(const AnnotatedLine &Line,
         (Left.is(TT_VerilogNumberBase) && Right.is(tok::numeric_constant))) {
       return false;
     }
+    // Add spaces around the implication operator `->`.
+    if (Left.is(tok::arrow) || Right.is(tok::arrow))
+      return true;
     // Don't add spaces between two at signs. Like in a coverage event.
     // Don't add spaces between at and a sensitivity list like
     // `@(posedge clk)`.

clang/unittests/Format/FormatTestVerilog.cpp

@@ -1005,7 +1005,7 @@ TEST_F(FormatTestVerilog, Operators) {
   verifyFormat("x = x ^~ x;");
   verifyFormat("x = x && x;");
   verifyFormat("x = x || x;");
-  verifyFormat("x = x->x;");
+  verifyFormat("x = x -> x;");
   verifyFormat("x = x <-> x;");
   verifyFormat("x += x;");
   verifyFormat("x -= x;");

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -1980,17 +1980,18 @@ TEST_F(TokenAnnotatorTest, UnderstandsVerilogOperators) {
   // joined operators, we don't have a separate type, so we only test for their
   // precedence.
   std::pair<prec::Level, std::string> JoinedBinary[] = {
-      {prec::Comma, "<->"},       {prec::Assignment, "+="},
-      {prec::Assignment, "-="},   {prec::Assignment, "*="},
-      {prec::Assignment, "/="},   {prec::Assignment, "%="},
-      {prec::Assignment, "&="},   {prec::Assignment, "^="},
-      {prec::Assignment, "<<="},  {prec::Assignment, ">>="},
-      {prec::Assignment, "<<<="}, {prec::Assignment, ">>>="},
-      {prec::LogicalOr, "||"},    {prec::LogicalAnd, "&&"},
-      {prec::Equality, "=="},     {prec::Equality, "!="},
-      {prec::Equality, "==="},    {prec::Equality, "!=="},
-      {prec::Equality, "==?"},    {prec::Equality, "!=?"},
-      {prec::ExclusiveOr, "~^"},  {prec::ExclusiveOr, "^~"},
+      {prec::Comma, "->"},        {prec::Comma, "<->"},
+      {prec::Assignment, "+="},   {prec::Assignment, "-="},
+      {prec::Assignment, "*="},   {prec::Assignment, "/="},
+      {prec::Assignment, "%="},   {prec::Assignment, "&="},
+      {prec::Assignment, "^="},   {prec::Assignment, "<<="},
+      {prec::Assignment, ">>="},  {prec::Assignment, "<<<="},
+      {prec::Assignment, ">>>="}, {prec::LogicalOr, "||"},
+      {prec::LogicalAnd, "&&"},   {prec::Equality, "=="},
+      {prec::Equality, "!="},     {prec::Equality, "==="},
+      {prec::Equality, "!=="},    {prec::Equality, "==?"},
+      {prec::Equality, "!=?"},    {prec::ExclusiveOr, "~^"},
+      {prec::ExclusiveOr, "^~"},
   };
   for (auto Operator : JoinedBinary) {
     auto Tokens = Annotate(std::string("x = x ") + Operator.second + " x;");