[clang-format] Fix crash involving array designators (#77045)

Fixes #76716
Fixes parsing of `[0]{}`. Before this patch it was begin parsed as a
lambda, now it is correctly parsed as a designator initializer.

Author: XDeme1

clang/lib/Format/UnwrappedLineParser.cpp

@@ -2308,7 +2308,7 @@ bool UnwrappedLineParser::tryToParseLambdaIntroducer() {
       LeftSquare->isCppStructuredBinding(Style)) {
     return false;
   }
-  if (FormatTok->is(tok::l_square))
+  if (FormatTok->is(tok::l_square) || tok::isLiteral(FormatTok->Tok.getKind()))
     return false;
   if (FormatTok->is(tok::r_square)) {
     const FormatToken *Next = Tokens->peekNextToken(/*SkipComment=*/true);

clang/lib/Format/WhitespaceManager.h

@@ -282,6 +282,7 @@ class WhitespaceManager {
     for (auto PrevIter = Start; PrevIter != End; ++PrevIter) {
       // If we broke the line the initial spaces are already
       // accounted for.
+      assert(PrevIter->Index < Changes.size());
       if (Changes[PrevIter->Index].NewlinesBefore > 0)
         NetWidth = 0;
       NetWidth +=

clang/unittests/Format/FormatTest.cpp

@@ -20931,6 +20931,12 @@ TEST_F(FormatTest, CatchAlignArrayOfStructuresRightAlignment) {
       "};",
       Style);
 
+  verifyNoCrash("Foo foo[] = {\n"
+                "    [0] = {1, 1},\n"
+                "    [1] { 1, 1, },\n"
+                "    [2] { 1, 1, },\n"
+                "};");
+
   verifyFormat("return GradForUnaryCwise(g, {\n"
                "                                {{\"sign\"}, \"Sign\",  "
                "  {\"x\", \"dy\"}},\n"
@@ -21173,6 +21179,12 @@ TEST_F(FormatTest, CatchAlignArrayOfStructuresLeftAlignment) {
       "};",
       Style);
 
+  verifyNoCrash("Foo foo[] = {\n"
+                "    [0] = {1, 1},\n"
+                "    [1] { 1, 1, },\n"
+                "    [2] { 1, 1, },\n"
+                "};");
+
   verifyFormat("return GradForUnaryCwise(g, {\n"
                "                                {{\"sign\"}, \"Sign\", {\"x\", "
                "\"dy\"}   },\n"

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -2324,6 +2324,11 @@ TEST_F(TokenAnnotatorTest, UnderstandDesignatedInitializers) {
   EXPECT_BRACE_KIND(Tokens[1], BK_BracedInit);
   EXPECT_TOKEN(Tokens[6], tok::period, TT_DesignatedInitializerPeriod);
   EXPECT_TOKEN(Tokens[13], tok::period, TT_DesignatedInitializerPeriod);
+
+  Tokens = annotate("Foo foo[] = {[0]{}};");
+  ASSERT_EQ(Tokens.size(), 14u) << Tokens;
+  EXPECT_TOKEN(Tokens[6], tok::l_square, TT_DesignatedInitializerLSquare);
+  EXPECT_BRACE_KIND(Tokens[9], BK_BracedInit);
 }
 
 TEST_F(TokenAnnotatorTest, UnderstandsJavaScript) {