[clang-tidy] Reduce false-positive ratio in misc-suspicious-missing-comma check.

Summary:
This patch is adding detection of common string literal patterns
that should not trigger warnings.

  [*] Add a limit on the number of concatenated token,
  [*] Add support for parenthese sequence of tokens,
  [*] Add detection of valid indentation.

As an example, this code will no longer trigger a warning:
```
const char* Array[] = {
  "first literal"
    "indented literal"
    "indented literal",
  "second literal",
  [...]
```

Reviewers: alexfh

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D18695

llvm-svn: 265303

1 files changed, 49 insertions, 1 deletions

diff --git a/clang-tools-extra/test/clang-tidy/misc-suspicious-missing-comma.cpp b/clang-tools-extra/test/clang-tidy/misc-suspicious-missing-comma.cpp
index 7b64fab45e8..0744d8f681a 100644
--- a/clang-tools-extra/test/clang-tidy/misc-suspicious-missing-comma.cpp
+++ b/clang-tools-extra/test/clang-tidy/misc-suspicious-missing-comma.cpp
@@ -15,7 +15,8 @@ const wchar_t* Colors[] = {
   L"Red", L"Yellow", L"Blue", L"Green", L"Purple", L"Rose", L"White", L"Black"
 };
 
-// The following array should not trigger any warnings.
+// The following array should not trigger any warnings. There is more than 5
+// elements, but they are all concatenated string literals.
 const char* HttpCommands[] = {
   "GET / HTTP/1.0\r\n"
   "\r\n",
@@ -26,9 +27,56 @@ const char* HttpCommands[] = {
   "GET /favicon.ico HTTP/1.0\r\n"
   "header: dummy"
   "\r\n",
+
+  "GET /index.html-en HTTP/1.0\r\n"
+  "\r\n",
+
+  "GET /index.html-fr HTTP/1.0\r\n"
+  "\r\n",
+
+  "GET /index.html-es HTTP/1.0\r\n"
+  "\r\n",
 };
 
 // This array is too small to trigger a warning.
 const char* SmallArray[] = {
   "a" "b", "c"
 };
+
+// Parentheses should be enough to avoid warnings.
+const char* ParentheseArray[] = {
+  ("a" "b"), "c",
+  ("d"
+   "e"
+   "f"),
+  "g", "h", "i", "j", "k", "l"
+};
+
+// Indentation should be enough to avoid warnings.
+const char* CorrectlyIndentedArray[] = {
+  "This is a long message "
+      "which is spanning over multiple lines."
+      "And this should be fine.",
+  "a", "b", "c", "d", "e", "f",
+  "g", "h", "i", "j", "k", "l"
+};
+
+const char* IncorrectlyIndentedArray[] = {
+  "This is a long message "
+  "which is spanning over multiple lines."
+      "And this should be fine.",
+  "a", "b", "c", "d", "e", "f",
+  "g", "h", "i", "j", "k", "l"
+};
+// CHECK-MESSAGES: :[[@LINE-6]]:3: warning: suspicious string literal, probably missing a comma [misc-suspicious-missing-comma]
+
+const char* TooManyConcatenatedTokensArray[] = {
+  "Dummy line",
+  "Dummy line",
+  "a" "b" "c" "d" "e" "f",
+  "g" "h" "i" "j" "k" "l",
+  "Dummy line",
+  "Dummy line",
+  "Dummy line",
+  "Dummy line",
+};