cbuilder: ccgexprs sweep part 3 (end) (#24410)

This finishes `ccgexprs` minus the sweeping refactors like moving
`NIM_NIL`, `NU8`, `NCSTRING` etc into constants.

compiler/cbuilderbase.nim

@@ -34,6 +34,8 @@ template cIntValue*(val: int64): Snippet = $val
 template cIntValue*(val: uint64): Snippet = $val
 template cIntValue*(val: Int128): Snippet = $val
 
+template cUintValue*(val: uint): Snippet = $val & "U"
+
 import std/formatfloat
 
 proc addFloatValue*(builder: var Builder, val: float) =

compiler/cbuilderdecls.nim

@@ -381,6 +381,12 @@ template addAnonUnion(obj: var Builder; body: typed) =
   body
   obj.add("};\n")
 
+template addUnionType(obj: var Builder; body: typed) =
+  ## adds a union type i.e. `union { ... }` with fields according to `body`
+  obj.add "union{\n"
+  body
+  obj.add("}")
+
 type DeclVisibility = enum
   None
   Extern

compiler/cbuilderexprs.nim

@@ -78,10 +78,12 @@ proc initCallBuilder(builder: var Builder, callee: Snippet): CallBuilder =
   builder.add(callee)
   builder.add("(")
 
+const cArgumentSeparator = ", "
+
 proc addArgumentSeparator(builder: var Builder) =
   # no-op on NIFC
   # used by "single argument" builders
-  builder.add(", ")
+  builder.add(cArgumentSeparator)
 
 template addArgument(builder: var Builder, call: var CallBuilder, valueBody: typed) =
   if call.needsComma:

compiler/cbuilderstmts.nim

@@ -203,3 +203,37 @@ template addIncr(builder: var Builder, val: Snippet) =
 template addDecr(builder: var Builder, val: Snippet) =
   builder.add(val)
   builder.add("--;\n")
+
+proc addInPlaceOp(builder: var Builder, binOp: TypedBinaryOp, t: Snippet, a, b: Snippet) =
+  builder.add(a)
+  builder.add(' ')
+  builder.add(typedBinaryOperators[binOp])
+  builder.add("= ")
+  builder.add(b)
+  builder.add(";\n")
+
+proc addInPlaceOp(builder: var Builder, binOp: UntypedBinaryOp, a, b: Snippet) =
+  builder.add(a)
+  builder.add(' ')
+  builder.add(untypedBinaryOperators[binOp])
+  builder.add("= ")
+  builder.add(b)
+  builder.add(";\n")
+
+proc cInPlaceOp(binOp: TypedBinaryOp, t: Snippet, a, b: Snippet): Snippet =
+  result = ""
+  result.add(a)
+  result.add(' ')
+  result.add(typedBinaryOperators[binOp])
+  result.add("= ")
+  result.add(b)
+  result.add(";\n")
+
+proc cInPlaceOp(binOp: UntypedBinaryOp, a, b: Snippet): Snippet =
+  result = ""
+  result.add(a)
+  result.add(' ')
+  result.add(untypedBinaryOperators[binOp])
+  result.add("= ")
+  result.add(b)
+  result.add(";\n")