[clang-tidy] misc-string-integer-assignment: ignore toupper/tolower

[courbet]

Summary

Tis represents ~20% of false positives. See PR27723.

[xazax.hun]

LGTM! Thanks for working on this.

[courbet]

Thanks.

clang-tools-extra/trunk/clang-tidy/bugprone/StringIntegerAssignmentCheck.cpp

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"))),
+          hasArgument(
+              1,
+              ignoringImpCasts(
+                  expr(hasType(isInteger()), unless(hasType(isAnyCharacter())),
+                       // Ignore calls to tolower/toupper (see PR27723).
+                       unless(callExpr(callee(functionDecl(
+                           hasAnyName("tolower", "std::tolower", "toupper",
+                                      "std::toupper"))))))
           unless(isInTemplateInstantiation())),
       this);
 }
 
 void StringIntegerAssignmentCheck::check(
     const MatchFinder::MatchResult &Result) {
   const auto *Argument = Result.Nodes.getNodeAs<Expr>("expr");
   SourceLocation Loc = Argument->getBeginLoc();

clang-tools-extra/trunk/test/clang-tidy/bugprone-string-integer-assignment.cpp

 // RUN: %check_clang_tidy %s bugprone-string-integer-assignment %t
 
 namespace std {
 template<typename T>
 struct basic_string {
   basic_string& operator=(T);
   basic_string& operator=(basic_string);
   basic_string& operator+=(T);
   basic_string& operator+=(basic_string);
 };
 
 typedef basic_string<char> string;
 typedef basic_string<wchar_t> wstring;
+
+int tolower(int i);
+int toupper(int i);
 }
 
+int tolower(int i);
+int toupper(int i);
+
 typedef int MyArcaneChar;
 
 int main() {
   std::string s;
   std::wstring ws;
   int x = 5;
 
   s = 6;
// CHECK-FIXES: {{^}}  ws += std::to_wstring(x);{{$}}
   ws += L'c';
   ws += (wchar_t)6;
 
   std::basic_string<MyArcaneChar> as;
   as = 6;
 // CHECK-MESSAGES: :[[@LINE-1]]:8: warning: an integer is interpreted as a chara
 // CHECK-FIXES: {{^}}  as = 6;{{$}}
 
+  s += toupper(x);
+  s += tolower(x);
+  s += std::tolower(x);
 }