[clang-tidy] fix readability-redundant-member-init auto-fix of Function-try-block

[AlexanderLanin]

Summary

This fixes https://bugs.llvm.org/show_bug.cgi?id=39310

[malcolm.parsons]

LGTM with some nits.

clang/lib/Format/TokenAnnotator.cpp

826

Comments should be sentences with a capital letter and a full stop.
Same for the other comments.

[AlexanderLanin]

Could someone commit this as I cannot? Thanks.
Alexander Lanin <[e-mail]>

clang-tools-extra/test/clang-tidy/checkers/modernize-use-default-member-init.cpp

 // This resulted in a warning by default.
 #define MACRO() \
   struct MacroS { \
     void *P; \
     MacroS() : P(nullptr) {} \
   };
 
 MACRO();
+
+
+class FunctionTryBlock {
+public:
+  FunctionTryBlock() try : i(5), k(8) {}
+  // CHECK-FIXES: FunctionTryBlock() try  {}
+  catch (...) {}
+
+private:
+  int i, k;
+  // CHECK-MESSAGES: :[[@LINE-1]]:7: warning: use default member initializer for 'i' [modernize-use-default-member-init]
+  // CHECK-MESSAGES: :[[@LINE-2]]:10: warning: use default member initializer for 'k' [modernize-use-default-member-init]
+  // CHECK-FIXES: int i{5}, k{8};
+};

clang/lib/Format/TokenAnnotator.cpp

case tok::colon:
           ++Contexts.back().FirstObjCSelectorName->ObjCSelectorNameParts;
         }
       } else if (Contexts.back().ColonIsForRangeExpr) {
         Tok->Type = TT_RangeBasedForLoopColon;
       } else if (CurrentToken && CurrentToken->is(tok::numeric_constant)) {
         Tok->Type = TT_BitFieldColon;
       } else if (Contexts.size() == 1 &&
                  !Line.First->isOneOf(tok::kw_enum, tok::kw_case)) {
-        if (Tok->getPreviousNonComment()->isOneOf(tok::r_paren,
-                                                  tok::kw_noexcept))
+        FormatToken *Prev = Tok->getPreviousNonComment();
+        if (Prev->isOneOf(tok::r_paren, tok::kw_noexcept))
           Tok->Type = TT_CtorInitializerColon;
-        else
+        else if (Prev->is(tok::kw_try)) {
+          // initialization within function try block
+          FormatToken *PrevPrev = Prev->getPreviousNonComment();
+          if (PrevPrev && PrevPrev->isOneOf(tok::r_paren, tok::kw_noexcept))
+            Tok->Type = TT_CtorInitializerColon;
+        } else
           Tok->Type = TT_InheritanceColon;
       } else if (canBeObjCSelectorComponent(*Tok->Previous) && Tok->Next &&
                  (Tok->Next->isOneOf(tok::r_paren, tok::comma) ||
                   (canBeObjCSelectorComponent(*Tok->Next) && Tok->Next->Next &&
                    Tok->Next->Next->is(tok::colon)))) {
         // This handles a special macro in ObjC code where selectors including
         // the colon are passed as macro arguments.
         Tok->Type = TT_ObjCMethodExpr;

clang/lib/Format/UnwrappedLineParser.cpp

 
 void UnwrappedLineParser::parseTryCatch() {
   assert(FormatTok->isOneOf(tok::kw_try, tok::kw___try) && "'try' expected");
   nextToken();
   bool NeedsUnwrappedLine = false;
   if (FormatTok->is(tok::colon)) {
     // We are in a function try block, what comes is an initializer list.
     nextToken();
+
+    // in case identifiers were removed by clang-tidy, what might follow is
+    // multiple commas in sequence - before the first identifier
+    while (FormatTok->is(tok::comma))
+      nextToken();
+
     while (FormatTok->is(tok::identifier)) {
       nextToken();
       if (FormatTok->is(tok::l_paren))
         parseParens();
-      if (FormatTok->is(tok::comma))
+
+      // in case identifiers were removed by clang-tidy, what might follow is
+      // multiple commas in sequence - after the first identifier
+      while (FormatTok->is(tok::comma))
         nextToken();
     }
   }
   // Parse try with resource.
   if (Style.Language == FormatStyle::LK_Java && FormatTok->is(tok::l_paren)) {
     parseParens();
   }
   if (FormatTok->is(tok::l_brace)) {

clang/unittests/Format/CleanupTest.cpp

TEST_F(CleanupTest, CtorInitializationSimpleRedundantComma) {
   Expected = "class A {\nA() : x(1) {} };";
   EXPECT_EQ(Expected, cleanupAroundOffsets({23}, Code));
 
   Code = "class A {\nA() :,,,,{} };";
   Expected = "class A {\nA() {} };";
   EXPECT_EQ(Expected, cleanupAroundOffsets({15}, Code));
 }
 
+// regression test for bug 39310
+TEST_F(CleanupTest, CtorInitializationSimpleRedundantCommaInFunctionTryBlock) {
+  std::string Code = "class A {\nA() try : , {} };";
+  std::string Expected = "class A {\nA() try  {} };";
+  EXPECT_EQ(Expected, cleanupAroundOffsets({21, 23}, Code));
+
+  Code = "class A {\nA() try : x(1), {} };";
+  Expected = "class A {\nA() try : x(1) {} };";
+  EXPECT_EQ(Expected, cleanupAroundOffsets({27}, Code));
+
+  Code = "class A {\nA() try :,,,,{} };";
+  Expected = "class A {\nA() try {} };";
+  EXPECT_EQ(Expected, cleanupAroundOffsets({19}, Code));
+
+  Code = "class A {\nA() try : x(1),,, {} };";
+  Expected = "class A {\nA() try : x(1) {} };";
+  EXPECT_EQ(Expected, cleanupAroundOffsets({27}, Code));
+
+  // do not remove every comma following a colon as it simply doesn't make
+  // sense in some situations
+  Code = "try : , {}";
+  Expected = "try : , {}";
+  EXPECT_EQ(Expected, cleanupAroundOffsets({8}, Code));
+}
+
 TEST_F(CleanupTest, CtorInitializationSimpleRedundantColon) {
   std::string Code = "class A {\nA() : =default; };";
   std::string Expected = "class A {\nA()  =default; };";
   EXPECT_EQ(Expected, cleanupAroundOffsets({15}, Code));
 
   Code = "class A {\nA() : , =default; };";
   Expected = "class A {\nA()  =default; };";
   EXPECT_EQ(Expected, cleanupAroundOffsets({15}, Code));