add test for multiple consecutive missing commas

Author: a-tarasyuk

clang/lib/Sema/SemaDecl.cpp

@@ -14710,11 +14710,9 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
     unsigned NumInits = ILE->getNumInits();
     if (NumInits > 2) {
       auto concatenatedPartsAt = [&](unsigned Index) -> unsigned {
-        const Expr *E = ILE->getInit(Index);
-        if (E) {
+        if (const Expr *E = ILE->getInit(Index))
           if (const auto *S = dyn_cast<StringLiteral>(E->IgnoreImpCasts()))
             return S->getNumConcatenated();
-        }
         return 0;
       };
 
@@ -14738,11 +14736,11 @@ void Sema::CheckCompleteVariableDeclaration(VarDecl *var) {
           unsigned R = I + 1 < NumInits ? concatenatedPartsAt(I + 1) : 0;
 
           // Skip neighbors with multi-part concatenations.
-          if (L > 1 || R > 1)
+          if (R > 1)
             continue;
 
           // Diagnose when at least one neighbor is a single literal.
-          if (L || R) {
+          if (R == 1 || L == 1) {
             SmallVector<FixItHint, 1> Hints;
             // Insert a comma between the two tokens of this element.
             Hints.push_back(FixItHint::CreateInsertion(

clang/test/Sema/string-concat.c

@@ -169,7 +169,7 @@ const char *extra_parens_to_suppress_warning[] = {
     "shared_future"
 };
 
-const char *multiple_missing_commas[] = {
+const char *multiple_missing_commas1[] = {
     "1",
     "2"  // expected-note {{place parentheses around the string literal to silence warning}}
     "3", // expected-warning {{suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma?}}
@@ -182,3 +182,17 @@ const char *multiple_missing_commas[] = {
     "10",
     "11",
 };
+
+const char *multiple_missing_commas2[] = {
+    "1",
+    "2"
+    "3"
+    "4"
+    "5",
+    "6"  // expected-note {{place parentheses around the string literal to silence warning}}
+    "7", // expected-warning {{suspicious concatenation of string literals in an array initialization; did you mean to separate the elements with a comma?}}
+    "8",
+    "9",
+    "10",
+    "11",
+};