[clang-tidy] modernize-loop-convert: impl const cast iter

Summary:
modernize-loop-convert was not detecting implicit casts to
const_iterator as convertible to range-based loops:

    std::vector<int> vec{1,2,3,4}
    for(std::vector<int>::const_iterator i = vec.begin();
        i != vec.end();
        ++i) { }

Thanks to Don Hinton for advice.

As well, this change adds a note for this check's applicability to code
targeting OpenMP prior to version 5 as this check will continue breaking
compilation with `-fopenmp`. Thanks to Roman Lebedev for pointing this
out.

Fixes PR#35082

Reviewed By: hintonda

Tags: #clang-tools-extra, #clang

Differential Revision: https://reviews.llvm.org/D61827

llvm-svn: 360785

1 files changed, 0 insertions, 5 deletions

diff --git a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
index f9e941c2016..0e59a8848d8 100644
--- a/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
+++ b/clang-tools-extra/clang-tidy/modernize/LoopConvertCheck.cpp
@@ -791,11 +791,6 @@ bool LoopConvertCheck::isConvertible(ASTContext *Context,
               CanonicalBeginType->getPointeeType(),
               CanonicalInitVarType->getPointeeType()))
         return false;
-    } else if (!Context->hasSameType(CanonicalInitVarType,
-                                     CanonicalBeginType)) {
-      // Check for qualified types to avoid conversions from non-const to const
-      // iterator types.
-      return false;
     }
   } else if (FixerKind == LFK_PseudoArray) {
     // This call is required to obtain the container.