fixed undoing bitfields on Windows

* It turns out that `bool` (_Bool) in bitfields may cause
  padding to the next 32-bit word.
  This was only observed on MinGW.
  I am not entirely sure why, although the C standard does
  not guarantee much with regard to bitfield memory layout
  and there are 64-bit available due to passing anyway.
  Actually, they could also be layed out in a different order.
* I am now consistently using guint instead of `bool` in bitfields
  to prevent any potential surprises.
* The way that guint was aliased with bitfield structs
  for undoing teco_machine_main_t and teco_machine_qregspec_t flags
  was therefore insecure.
  It was not guaranteed that the __flags field really "captures"
  all of the bit field.
  Even with `guint v : 1` fields, this was not guaranteed.
  We would have required a static assertion for robustness.
  Alternatively, we could have declared a `gsize __flags` variable
  as well. This __should__ be safe since gsize should always be
  pointer sized and correspond to the platform's alignment.
  However, it's also not 100% guaranteed.
  Using classic ANSI C enums with bit operations to encode multiple
  fields and flags into a single integer also doesn't look very
  attractive.
* Instead, we now define scalar types with their own teco_undo_push()
  shortcuts for the bitfield structs.
  This is in one way simpler and much more robust, but on the other
  hand complicates access to the flag variables.
* It's a good question whether a `struct __attribute__((packed))` bitfield
  with guint fields would be a reliable replacement for flag enums, that
  are communicated with the "outside" (TECO) world.
  I am not going to risk it until GCC gives any guarantees, though.
  For the time being, bitfields are only used internally where
  the concrete memory layout (bit positions) is not crucial.
* This fixes the test suite and therefore probably CI and nightly
  builds on Windows.
* Test case: Rub out `@I//` or `@Xq` until before the `@`.
  The parser doesn't know that `@` is still set and allows
  all sorts of commands where `@` should be forbidden.
* It's unknown how long this has been broken on Windows - quite
  possibly since v2.0.

1 files changed, 4 insertions, 4 deletions

diff --git a/src/lexer.c b/src/lexer.c
index 84ddcc3..5e6202d 100644
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -64,7 +64,7 @@ teco_lexer_getstyle(teco_view_t *view, teco_machine_main_t *machine,
 		gsize macro_pc = machine->macro_pc;
 		teco_machine_main_clear(machine);
 		teco_machine_main_init(machine, NULL, FALSE);
-		machine->mode = TECO_MODE_LEXING;
+		machine->flags.mode = TECO_MODE_LEXING;
 		machine->macro_pc = macro_pc;
 
 		return SCE_SCITECO_INVALID;
@@ -164,7 +164,7 @@ teco_lexer_step(teco_view_t *view, teco_machine_main_t *machine,
 
 	if (style != SCE_SCITECO_INVALID &&
 	    machine->parent.current->keymacro_mask & TECO_KEYMACRO_MASK_START &&
-	    !machine->modifier_at)
+	    !machine->flags.modifier_at)
 		/* clean parser state */
 		*safe_col = *cur_col;
 }
@@ -206,12 +206,12 @@ teco_lexer_style(teco_view_t *view, gsize end)
 
 	g_auto(teco_machine_main_t) machine;
 	teco_machine_main_init(&machine, NULL, FALSE);
-	machine.mode = TECO_MODE_LEXING;
+	machine.flags.mode = TECO_MODE_LEXING;
 
 	/* for lexing the contents of @^Uq{...} */
 	g_auto(teco_machine_main_t) macrodef_machine;
 	teco_machine_main_init(&macrodef_machine, NULL, FALSE);
-	macrodef_machine.mode = TECO_MODE_LEXING;
+	macrodef_machine.flags.mode = TECO_MODE_LEXING;
 
 	g_assert(start_col >= 0);
 	guint col = start_col;