[clang] Reject _Complex _BitInt (#119402)

The C standard doesn't require support for these types and Codegen for
these types is incorrect ATM.
See #119352

Author: Fznamznon

clang/docs/ReleaseNotes.rst

@@ -61,6 +61,8 @@ code bases.
 C/C++ Language Potentially Breaking Changes
 -------------------------------------------
 
+- Clang now rejects ``_Complex _BitInt`` types.
+
 C++ Specific Potentially Breaking Changes
 -----------------------------------------
 

clang/lib/Sema/DeclSpec.cpp

@@ -1343,8 +1343,7 @@ void DeclSpec::Finish(Sema &S, const PrintingPolicy &Policy) {
                               S.getLocForEndOfToken(getTypeSpecComplexLoc()),
                                                  " double");
       TypeSpecType = TST_double;   // _Complex -> _Complex double.
-    } else if (TypeSpecType == TST_int || TypeSpecType == TST_char ||
-               TypeSpecType == TST_bitint) {
+    } else if (TypeSpecType == TST_int || TypeSpecType == TST_char) {
       // Note that this intentionally doesn't include _Complex _Bool.
       if (!S.getLangOpts().CPlusPlus)
         S.Diag(TSTLoc, diag::ext_integer_complex);

clang/test/AST/ByteCode/complex.cpp

@@ -146,11 +146,6 @@ constexpr _Complex int I3 = {15};
 static_assert(__real(I3) == 15, "");
 static_assert(__imag(I3) == 0, "");
 
-constexpr _Complex _BitInt(8) A = {4};
-static_assert(__real(A) == 4, "");
-static_assert(__imag(A) == 0, "");
-
-
 constexpr _Complex double Doubles[4] = {{1.0, 2.0}};
 static_assert(__real(Doubles[0]) == 1.0, "");
 static_assert(__imag(Doubles[0]) == 2.0, "");
@@ -163,9 +158,6 @@ static_assert(__imag(Doubles[3]) == 0.0, "");
 
 static_assert(~(0.5 + 1.5j) == (0.5 + -1.5j), "");
 
-static_assert(__extension__ __imag(A) == 0, "");
-static_assert(__imag(__extension__ A) == 0, "");
-
 void func(void) {
   __complex__ int arr;
   _Complex int result;

clang/test/CodeGenCXX/ext-int.cpp

@@ -549,24 +549,6 @@ void Shift(_BitInt(28) Ext, _BitInt(65) LargeExt, int i) {
   // CHECK: ashr i65 {{.+}}, %[[PROMO]]
 }
 
-void ComplexTest(_Complex _BitInt(12) first, _Complex _BitInt(33) second) {
-  // LIN: define{{.*}} void @_Z11ComplexTestCDB12_CDB33_
-  // WIN: define dso_local void  @"?ComplexTest@@YAXU?$_Complex@U?$_BitInt@$0M@@__clang@@@__clang@@U?$_Complex@U?$_BitInt@$0CB@@__clang@@@2@@Z"
-  first + second;
-  // CHECK: %[[FIRST_REALP:.+]] = getelementptr inbounds nuw { i12, i12 }, ptr %{{.+}}, i32 0, i32 0
-  // CHECK: %[[FIRST_REAL:.+]] = load i12, ptr %[[FIRST_REALP]]
-  // CHECK: %[[FIRST_IMAGP:.+]] = getelementptr inbounds nuw { i12, i12 }, ptr %{{.+}}, i32 0, i32 1
-  // CHECK: %[[FIRST_IMAG:.+]] = load i12, ptr %[[FIRST_IMAGP]]
-  // CHECK: %[[FIRST_REAL_CONV:.+]] = sext i12 %[[FIRST_REAL]]
-  // CHECK: %[[FIRST_IMAG_CONV:.+]] = sext i12 %[[FIRST_IMAG]]
-  // CHECK: %[[SECOND_REALP:.+]] = getelementptr inbounds nuw { i33, i33 }, ptr %{{.+}}, i32 0, i32 0
-  // CHECK: %[[SECOND_REAL:.+]] = load i33, ptr %[[SECOND_REALP]]
-  // CHECK: %[[SECOND_IMAGP:.+]] = getelementptr inbounds nuw { i33, i33 }, ptr %{{.+}}, i32 0, i32 1
-  // CHECK: %[[SECOND_IMAG:.+]] = load i33, ptr %[[SECOND_IMAGP]]
-  // CHECK: %[[REAL:.+]] = add i33 %[[FIRST_REAL_CONV]], %[[SECOND_REAL]]
-  // CHECK: %[[IMAG:.+]] = add i33 %[[FIRST_IMAG_CONV]], %[[SECOND_IMAG]]
-}
-
 typedef  _BitInt(64) vint64_t16 __attribute__((vector_size(16)));
 void VectorTest(vint64_t16 first, vint64_t16 second) {
   // LIN: define{{.*}} void @_Z10VectorTestDv2_DB64_S0_(<2 x i64> %{{.+}}, <2 x i64> %{{.+}})

clang/test/SemaCXX/ext-int.cpp

@@ -101,8 +101,10 @@ typedef _BitInt(37) __attribute__((vector_size(16))) VecTy4;
 // expected-error@+1{{'_BitInt' vector element width must be a power of 2}}
 typedef _BitInt(37) __attribute__((ext_vector_type(32))) OtherVecTy4;
 
-// Allow _Complex:
+// expected-error@+1{{'_Complex _BitInt' is invalid}}
 _Complex _BitInt(3) Cmplx;
+// expected-error@+1{{'_Complex _BitInt' is invalid}}
+typedef _Complex _BitInt(3) Cmp;
 
 // Reject cases of _Atomic:
 // expected-error@+1{{_Atomic cannot be applied to integer type '_BitInt(4)'}}