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| author | Herbert Valerio Riedel <hvr@gnu.org> | 2015-12-31 21:02:50 +0100 |
|---|---|---|
| committer | Herbert Valerio Riedel <hvr@gnu.org> | 2015-12-31 21:08:25 +0100 |
| commit | eae40e16a0933fe3b6cb0ee4dc9cdbe3d21e44ce (patch) | |
| tree | c6f7fe97e9b22fbed51da5da0ba22d08f116efeb /docs/users_guide/phases.rst | |
| parent | 351dea4a7c07f4e845eac6c2e895f6f41524b40c (diff) | |
| download | haskell-eae40e16a0933fe3b6cb0ee4dc9cdbe3d21e44ce.tar.gz | |
Use 0/1 instead of YES/NO as `__GLASGOW_HASKELL_TH__` macro value
Using `YES`/`NO` causes all sorts of problems as CPP doesn't work on
symbolic tokens but rather on scalar values.
A use like
#if __GLASGOW_HASKELL_TH__==YES
{-# LANGUAGE TemplateHaskell #-}
#endif
doesn't do what one may naively expect, and neither does
#if __GLASGOW_HASKELL_TH__
{-# LANGUAGE TemplateHaskell #-}
#endif
*unless* `YES` happens to evaluate to a non-zero scalar.
`__GLASGOW_HASKELL_TH__ was originally introduced via D396 / #9734.
Fixes #11322
Reviewed By: austin
Differential Revision: https://phabricator.haskell.org/D1723
Diffstat (limited to 'docs/users_guide/phases.rst')
| -rw-r--r-- | docs/users_guide/phases.rst | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/docs/users_guide/phases.rst b/docs/users_guide/phases.rst index 1c48cfceb6..cc4244eff3 100644 --- a/docs/users_guide/phases.rst +++ b/docs/users_guide/phases.rst @@ -328,8 +328,8 @@ defined by your local GHC installation, the following trick is useful: .. index:: single: __GLASGOW_HASKELL_TH__ - This is set to ``YES`` when the compiler supports Template Haskell, - and to ``NO`` when not. The latter is the case for a stage-1 + This is set to ``1`` when the compiler supports Template Haskell, + and to ``0`` when not. The latter is the case for a stage-1 compiler during bootstrapping, or on architectures where the interpreter is not available. |