Named arguments in commands + many grammar fixes (#20994)

* Breaking parser changes, implement https://github.com/nim-lang/RFCs/issues/442

Types are separated from expressions and better reflected in the grammar.

* add test

* more accurate grammar

* fix keyword typedescs

* accept expressions in proc argument lists

* CI "fixes"

* fixes

* allow full ref expressions again, adapt old tests

* cleanup, fix some tests

* improve grammar, try and revert semtypes change

* restrict sigil binding to identOrLiteral

* fix, should have caught this immediately

* add changelog entry, fix double not nil bug

* correct grammar

* change section

* fix

* real fix hopefully

* fix test

* support LL(1) for tuples

* make grammar.txt too

tests/parser/tcommand_as_expr.nim

@@ -36,3 +36,12 @@ echo f -4
 
 echo int -1 # doesn't compile
 echo int `-` 1 # compiles
+
+var num = 1
+num += int 2
+doAssert num == 3
+
+import options
+var opt = some some none int
+opt = some some none int
+opt = some none Option[int]

tests/parser/tcommandequals.nim

@@ -0,0 +1,17 @@
+discard """
+  output: '''
+5
+'''
+"""
+
+proc foo(a, b: int) =
+  echo a + b
+
+foo a = 2, b = 3
+
+import macros
+
+macro bar(args: varargs[untyped]): untyped =
+  doAssert args[0].kind == nnkExprEqExpr
+
+bar "a" = 1

tests/parser/tcommandindent.nim

@@ -0,0 +1,16 @@
+when false: # parse the following
+  let foo = Obj(
+    field1: proc (src: pointer, srcLen: Natural)
+                    {.nimcall, gcsafe, raises: [IOError, Defect].} =
+      var file = FileOutputStream(s).file
+
+      implementWrites s.buffers, src, srcLen, "FILE",
+                      writeStartAddr, writeLen,
+        file.writeBuffer(writeStartAddr, writeLen)
+    ,
+    field2: proc {.nimcall, gcsafe, raises: [IOError, Defect].} =
+      flushFile FileOutputStream(s).file
+    ,
+    field3: proc () {.nimcall, gcsafe, raises: [IOError, Defect].} =
+      close FileOutputStream(s).file
+  )

tests/parser/tdoublenotnil.nim

@@ -0,0 +1,3 @@
+when false:
+  type Foo = Bar not nil not nil #[tt.Error
+                         ^ invalid indentation]#

tests/parser/ttypeexprobject.nim

@@ -0,0 +1,10 @@
+discard """
+  errormsg: "invalid indentation"
+  line: 10
+  column: 14
+"""
+
+type
+  A = (object | tuple | int)
+  B = int | object | tuple
+  C = object | tuple | int # issue #8846

tests/parser/ttypeexprs.nim

@@ -0,0 +1,25 @@
+proc foo[T: ptr int | ptr string](x: T) = discard
+var x = "abc"
+foo(addr x)
+
+let n = 3'u32
+type Double = (
+  when n.sizeof == 4: uint64
+  elif n.sizeof == 2: uint32
+  else: uint16
+)
+
+type
+  A = (ref | ptr | pointer)
+  B = pointer | ptr | ref
+  C = ref | ptr | pointer
+
+template `+`(a, b): untyped = (b, a)
+template `*`(a, b): untyped = (a, b)
+
+doAssert (ref int + ref float * ref string + ref bool) is
+  (ref bool, ((ref float, ref string), ref int))
+type X = ref int + ref float * ref string + ref bool
+doAssert X is (ref bool, ((ref float, ref string), ref int))
+
+type SomePointer = proc | ref | ptr | pointer