[clang-tidy] misc-string-integer-assignment: fix false positive

[courbet]

Summary

using CodePoint = uint32_t;
CodePoint cp;
casic_string<CodePoint> s;
s += cp;

See PR27723. (https://bugs.llvm.org/show_bug.cgi?id=27723)

[xazax.hun]

The change looks good but it would be great to have a regression test as well.

[courbet]

• add more tests
• Traverse using decls.

[JonasToth]

LGTM.
is there a bug or similar? If yes please mention it somewhere in the summary or so and close it :)

[alexfh]

LG. Thanks for improving this check!

[courbet]

Thanks !

is there a bug or similar? If yes please mention it somewhere in the summary or so and close it :)

Yes, PR27723. Done.

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

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"))))))),
+              hasTemplateArgument(0, refersToType(hasCanonicalType(
+                                         qualType().bind("type")))))))),
           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"))))))
+                                      "std::toupper"))))),
+                       // Do not warn if assigning e.g. `CodePoint` to
+                       // `basic_string<CodePoint>`
+                       unless(hasType(qualType(
+                           hasCanonicalType(equalsBoundNode("type"))))))
                       .bind("expr"))),
           unless(isInTemplateInstantiation())),
       this);
 }
 
 void StringIntegerAssignmentCheck::check(
     const MatchFinder::MatchResult &Result) {
   const auto *Argument = Result.Nodes.getNodeAs<Expr>("expr");

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

// CHECK-FIXES: {{^}}  ws += L"66";{{$}}
   ws += x;
 // CHECK-MESSAGES: :[[@LINE-1]]:9: warning: an integer is interpreted as a chara
 // CHECK-FIXES: {{^}}  ws += std::to_wstring(x);{{$}}
   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;{{$}}
+  as = static_cast<MyArcaneChar>(6);
+  as = 'a';
 
   s += toupper(x);
   s += tolower(x);
   s += std::tolower(x);
 }