1 files changed, 80 insertions, 0 deletions
diff --git a/clang-tools-extra/clang-tidy/misc/SuspiciousMissingCommaCheck.cpp b/clang-tools-extra/clang-tidy/misc/SuspiciousMissingCommaCheck.cpp
new file mode 100644
index 00000000000..a3a479c89b3
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/SuspiciousMissingCommaCheck.cpp
@@ -0,0 +1,80 @@
+//===--- SuspiciousMissingCommaCheck.cpp - clang-tidy----------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "SuspiciousMissingCommaCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+namespace misc {
+
+namespace {
+
+AST_MATCHER(StringLiteral, isConcatenatedLiteral) {
+  return Node.getNumConcatenated() > 1;
+}
+
+}  // namespace
+
+SuspiciousMissingCommaCheck::SuspiciousMissingCommaCheck(
+    StringRef Name, ClangTidyContext *Context)
+    : ClangTidyCheck(Name, Context),
+      SizeThreshold(Options.get("SizeThreshold", 5U)),
+      RatioThreshold(std::stod(Options.get("RatioThreshold", ".2"))) {}
+
+void SuspiciousMissingCommaCheck::storeOptions(
+    ClangTidyOptions::OptionMap &Opts) {
+  Options.store(Opts, "SizeThreshold", SizeThreshold);
+  Options.store(Opts, "RatioThreshold", std::to_string(RatioThreshold));
+}
+
+void SuspiciousMissingCommaCheck::registerMatchers(MatchFinder *Finder) {
+  const auto ConcatenatedStringLiteral =
+      stringLiteral(isConcatenatedLiteral()).bind("str");
+
+  const auto StringsInitializerList =
+      initListExpr(hasType(constantArrayType()),
+                   has(expr(ignoringImpCasts(ConcatenatedStringLiteral))));
+
+  Finder->addMatcher(StringsInitializerList.bind("list"), this);
+}
+
+void SuspiciousMissingCommaCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *InitializerList = Result.Nodes.getNodeAs<InitListExpr>("list");
+  const auto *ConcatenatedLiteral = Result.Nodes.getNodeAs<Expr>("str");
+  assert(InitializerList && ConcatenatedLiteral);
+
+  // Skip small arrays as they often generate false-positive.
+  unsigned int Size = InitializerList->getNumInits();
+  if (Size < SizeThreshold) return;
+
+  // Count the number of occurence of concatenated string literal.
+  unsigned int Count = 0;
+  for (unsigned int i = 0; i < Size; ++i) {
+    const Expr *Child = InitializerList->getInit(i)->IgnoreImpCasts();
+    if (const auto *Literal = dyn_cast<StringLiteral>(Child)) {
+      if (Literal->getNumConcatenated() > 1) ++Count;
+    }
+  }
+
+  // Warn only when concatenation is not common in this initializer list.
+  // The current threshold is set to less than 1/5 of the string literals.
+  if (double(Count) / Size > RatioThreshold) return;
+
+  diag(ConcatenatedLiteral->getLocStart(),
+       "suspicious string literal, probably missing a comma");
+}
+
+}  // namespace misc
+}  // namespace tidy
+}  // namespace clang