Merge pull request github#13887 from jketema/float128x

C++: Remove support for `_Float128x` which is not actually supported by gcc

Author: MathiasVP

cpp/downgrades/d77c09d8bdc172c9201dec293de1e14c931d3f05/old.dbscheme

@@ -0,0 +1,2 @@
+description: Remove _Float128 type
+compatibility: full

cpp/downgrades/d77c09d8bdc172c9201dec293de1e14c931d3f05/semmlecode.cpp.dbscheme

@@ -0,0 +1,4 @@
+---
+category: minorAnalysis
+---
+* The `_Float128x` type is no longer exposed as a builtin type. As this type could not occur any code base, this should only affect queries that explicitly looked at the builtin types.

cpp/downgrades/d77c09d8bdc172c9201dec293de1e14c931d3f05/upgrade.properties

@@ -814,9 +814,6 @@ private predicate floatingPointTypeMapping(
   // _Float128
   kind = 49 and base = 2 and domain = TRealDomain() and realKind = 49 and extended = false
   or
-  // _Float128x
-  kind = 50 and base = 2 and domain = TRealDomain() and realKind = 50 and extended = true
-  or
   // _Float16
   kind = 52 and base = 2 and domain = TRealDomain() and realKind = 52 and extended = false
   or

cpp/ql/lib/change-notes/2023-08-07-removal-of-float128x.md

@@ -608,7 +608,7 @@ case @builtintype.kind of
 | 47 = @std_float64           // _Float64
 | 48 = @float64x              // _Float64x
 | 49 = @std_float128          // _Float128
-| 50 = @float128x             // _Float128x
+// ... 50 _Float128x
 | 51 = @char8_t
 | 52 = @float16               // _Float16
 | 53 = @complex_float16       // _Complex _Float16