[clang-tidy] ignore predefined expressions in cppcoreguidelines-pro-bounds-array-to-pointer-decay check

[lewmpk]

Summary

Bugzilla: 40852

 c++
int main()
{
  const char* a = __FILE__; 
  const char* b = __FUNCTION__; 
}

variable b is now not marked as an error by cppcoreguidelines-pro-bounds-array-to-pointer-decay check

[lebedev.ri]

See D22196.

[lewmpk]

Okk, it seems that the consensus is that __FUNCTION__ should not be cast to char*. ( I'll research a bit before I pick up a task in the future :) )
I'm happy to abandon this diff - any objections?

[JonasToth]

You can abondon this. A short justification (with reference to the other revision) on the bug report would be great!

clang-tidy/cppcoreguidelines/ProBoundsArrayToPointerDecayCheck.cpp

 void ProBoundsArrayToPointerDecayCheck::registerMatchers(MatchFinder *Finder) {
   if (!getLangOpts().CPlusPlus)
     return;
 
   // The only allowed array to pointer decay
   // 1) just before array subscription
   // 2) inside a range-for over an array
   // 3) if it converts a string literal to a pointer
+  // 4) if it converts a predefined value to a pointer
   Finder->addMatcher(
       implicitCastExpr(
           unless(hasParent(arraySubscriptExpr())),
           unless(hasParentIgnoringImpCasts(explicitCastExpr())),
           unless(isInsideOfRangeBeginEndStmt()),
-          unless(hasSourceExpression(ignoringParens(stringLiteral()))))
+          unless(hasSourceExpression(ignoringParens(stringLiteral()))),
+          unless(hasSourceExpression(ignoringParens(predefinedExpr()))))
           .bind("cast"),
       this);
 }
 
 void ProBoundsArrayToPointerDecayCheck::check(
     const MatchFinder::MatchResult &Result) {
   const auto *MatchedCast = Result.Nodes.getNodeAs<ImplicitCastExpr>("cast");
   if (MatchedCast->getCastKind() != CK_ArrayToPointerDecay)

test/clang-tidy/cppcoreguidelines-pro-bounds-array-to-pointer-decay.cpp

 
 const char *g() {
   return "clang"; // OK, decay string literal to pointer
 }
 const char *g2() {
     return ("clang"); // OK, ParenExpr hides the literal-pointer decay
 }
 
+const char *line = __FILE__; // OK
+const char *func = __FUNCTION__; // OK, predefined value to pointer
+
 void f2(void *const *);
 void bug25362() {
   void *a[2];
   f2(static_cast<void *const*>(a)); // OK, explicit cast
 }