From e9f095edc1b3246d913ec534c9204d54fe256f0c Mon Sep 17 00:00:00 2001 From: Timothee Cour Date: Mon, 4 May 2020 16:05:09 -0700 Subject: [PATCH] fixup --- doc/manual.rst | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/doc/manual.rst b/doc/manual.rst index d1c151924a59b..16ecbc2822e8e 100644 --- a/doc/manual.rst +++ b/doc/manual.rst @@ -6412,26 +6412,27 @@ CompleteStruct pragma ----------------------- By default, `importc` types are considered incomplete: they may be lacking fields in their nim declaration because these are unused in nim code or because of ABI -differences across platforms, in particular for padding fields. Field reordering +differences across platforms, in particular for padding fields. Field reorderings are also allowed. This prevents using `sizeof`, `alignof`, `offsetOf` at compile time. -These can still be used at runtime, deferring to calling ``sizeof`` (+ friends) in the +These can still be used at runtime, deferring to calling `sizeof` (+ friends) in the backend generated code. In this case, they're known at backend compile time, but not during nim semantic phase. -This ``completeStruct`` pragma overrides this behavior by telling the compiler -the type declaration in nim is fully specified, so that `sizeof`, `alignof`, `offsetOf` -are available at compile time. As a sanity check, `-d:checkAbi` will insert -cgen static checks to make sure at least sizeof is correct. +This `completeStruct` pragma overrides this behavior by telling the compiler +the type declaration in nim is fully specified and in correct order so that +`sizeof`, `alignof`, `offsetOf` are available at compile time. +As a sanity check, `-d:checkAbi` will insert backend static checks to make sure +at least `sizeof` is correct. .. code-block:: Nim type - TFoo* {.importc: "Foo", header: "", - pure, completeStruct.} = object - x*: cint # only 1 field in C declaration + TFoo* {.importc: "struct Foo", header: "", completeStruct.} = object + s1*: cint + x2* {.importc: "_x2"}: pointer # renamed field -See `tests `_ -The ``incompleteStruct`` pragma is now deprecated as it was implying the wrong +See `additional examples `_. +The `incompleteStruct` pragma is now deprecated as it was implying the wrong default. Compile pragma