Revert "[Sema] Add check for bitfield assignments to integral types (#69049)"

This reverts commit 708808e which is
causing crashes on valid code, see
#69049 (comment).

Author: kadircet

clang/docs/ReleaseNotes.rst

@@ -211,9 +211,6 @@ New Compiler Flags
   the preprocessed text to the output. This can greatly reduce the size of the
   preprocessed output, which can be helpful when trying to reduce a test case.
 
-* ``-Wbitfield-conversion`` was added to detect assignments of integral
-  types to a bitfield that may change the value.
-
 Deprecated Compiler Flags
 -------------------------
 

clang/include/clang/Basic/DiagnosticGroups.td

@@ -53,7 +53,6 @@ def SingleBitBitFieldConstantConversion :
 def BitFieldConstantConversion : DiagGroup<"bitfield-constant-conversion",
                                            [SingleBitBitFieldConstantConversion]>;
 def BitFieldEnumConversion : DiagGroup<"bitfield-enum-conversion">;
-def BitFieldConversion : DiagGroup<"bitfield-conversion">;
 def BitFieldWidth : DiagGroup<"bitfield-width">;
 def CompoundTokenSplitByMacro : DiagGroup<"compound-token-split-by-macro">;
 def CompoundTokenSplitBySpace : DiagGroup<"compound-token-split-by-space">;
@@ -936,7 +935,6 @@ def Conversion : DiagGroup<"conversion",
                             ConstantConversion,
                             EnumConversion,
                             BitFieldEnumConversion,
-                            BitFieldConversion,
                             FloatConversion,
                             Shorten64To32,
                             IntConversion,

clang/include/clang/Basic/DiagnosticSemaKinds.td

@@ -6191,9 +6191,6 @@ def warn_signed_bitfield_enum_conversion : Warning<
   "signed bit-field %0 needs an extra bit to represent the largest positive "
   "enumerators of %1">,
   InGroup<BitFieldEnumConversion>, DefaultIgnore;
-def warn_bitfield_too_small_for_integral_type : Warning<
-  "conversion from %2 (%3 bits) to bit-field %0 (%1 bits) may change value">,
-  InGroup<BitFieldConversion>, DefaultIgnore;
 def note_change_bitfield_sign : Note<
   "consider making the bitfield type %select{unsigned|signed}0">;
 

clang/lib/Sema/SemaChecking.cpp

@@ -14332,18 +14332,6 @@ static bool AnalyzeBitFieldAssignment(Sema &S, FieldDecl *Bitfield, Expr *Init,
         S.Diag(WidthExpr->getExprLoc(), diag::note_widen_bitfield)
             << BitsNeeded << ED << WidthExpr->getSourceRange();
       }
-    } else if (OriginalInit->getType()->isIntegralType(S.Context)) {
-      IntRange LikelySourceRange =
-          GetExprRange(S.Context, Init, S.isConstantEvaluatedContext(),
-                       /*Approximate=*/true);
-
-      if (LikelySourceRange.Width > FieldWidth) {
-        Expr *WidthExpr = Bitfield->getBitWidth();
-        S.Diag(InitLoc, diag::warn_bitfield_too_small_for_integral_type)
-            << Bitfield << FieldWidth << OriginalInit->getType()
-            << LikelySourceRange.Width;
-        S.Diag(WidthExpr->getExprLoc(), diag::note_declared_at);
-      }
     }
 
     return false;
@@ -15241,6 +15229,7 @@ static void CheckImplicitConversion(Sema &S, Expr *E, QualType T,
 
   if (LikelySourceRange.Width > TargetRange.Width) {
     // If the source is a constant, use a default-on diagnostic.
+    // TODO: this should happen for bitfield stores, too.
     Expr::EvalResult Result;
     if (E->EvaluateAsInt(Result, S.Context, Expr::SE_AllowSideEffects,
                          S.isConstantEvaluatedContext())) {