[clang-tidy] Check for suspicious string assignments.

It is possible to assign arbitrary integer types to strings.
Sometimes it is the result of missing to_string call or apostrophes.

Reviewers: alexfh

Differential Revision: http://reviews.llvm.org/D15411

llvm-svn: 255630

1 files changed, 85 insertions, 0 deletions

diff --git a/clang-tools-extra/clang-tidy/misc/StringIntegerAssignmentCheck.cpp b/clang-tools-extra/clang-tidy/misc/StringIntegerAssignmentCheck.cpp
new file mode 100644
index 00000000000..c9ed466ccc3
--- /dev/null
+++ b/clang-tools-extra/clang-tidy/misc/StringIntegerAssignmentCheck.cpp
@@ -0,0 +1,85 @@
+//===--- StringIntegerAssignmentCheck.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 "StringIntegerAssignmentCheck.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/ASTMatchers/ASTMatchFinder.h"
+#include "clang/Lex/Lexer.h"
+
+using namespace clang::ast_matchers;
+
+namespace clang {
+namespace tidy {
+
+void StringIntegerAssignmentCheck::registerMatchers(MatchFinder *Finder) {
+  if (!getLangOpts().CPlusPlus)
+    return;
+  Finder->addMatcher(
+      cxxOperatorCallExpr(
+          anyOf(hasOverloadedOperatorName("="),
+                hasOverloadedOperatorName("+=")),
+          callee(cxxMethodDecl(ofClass(classTemplateSpecializationDecl(
+              hasName("::std::basic_string"),
+              hasTemplateArgument(0, refersToType(qualType().bind("type"))))))),
+          hasArgument(1,
+                      ignoringImpCasts(expr(hasType(isInteger()),
+                                            unless(hasType(isAnyCharacter())))
+                                           .bind("expr"))),
+          unless(isInTemplateInstantiation())),
+      this);
+}
+
+void StringIntegerAssignmentCheck::check(
+    const MatchFinder::MatchResult &Result) {
+  const auto *Argument = Result.Nodes.getNodeAs<Expr>("expr");
+  SourceLocation Loc = Argument->getLocStart();
+
+  auto Diag =
+      diag(Loc, "an integer is interpreted as a character code when assigning "
+                "it to a string; if this is intended, cast the integer to the "
+                "appropriate character type; if you want a string "
+                "representation, use the appropriate conversion facility");
+
+  if (Loc.isMacroID())
+    return;
+
+  auto CharType = *Result.Nodes.getNodeAs<QualType>("type");
+  bool IsWideCharType = CharType->isWideCharType();
+  if (!CharType->isCharType() && !IsWideCharType)
+    return;
+  bool IsOneDigit = false;
+  bool IsLiteral = false;
+  if (const auto *Literal = dyn_cast<IntegerLiteral>(Argument)) {
+    IsOneDigit = Literal->getValue().getLimitedValue() < 10;
+    IsLiteral = true;
+  }
+
+  SourceLocation EndLoc = Lexer::getLocForEndOfToken(
+      Argument->getLocEnd(), 0, *Result.SourceManager,
+      Result.Context->getLangOpts());
+  if (IsOneDigit) {
+    Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "L'" : "'")
+         << FixItHint::CreateInsertion(EndLoc, "'");
+    return;
+  }
+  if (IsLiteral) {
+    Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "L\"" : "\"")
+         << FixItHint::CreateInsertion(EndLoc, "\"");
+    return;
+  }
+
+  if (getLangOpts().CPlusPlus11) {
+    Diag << FixItHint::CreateInsertion(Loc, IsWideCharType ? "std::to_wstring("
+                                                           : "std::to_string(")
+         << FixItHint::CreateInsertion(EndLoc, ")");
+  }
+}
+
+} // namespace tidy
+} // namespace clang