From: sof <unknown>
Date: Thu, 4 Feb 1999 15:20:32 +0000 (+0000)
Subject: [project @ 1999-02-04 15:20:32 by sof]
X-Git-Tag: Approximately_9120_patches~6607
X-Git-Url: http://git.megacz.com/?a=commitdiff_plain;h=233b9c713c9061775634eeff8af7324ba281d2d9;p=ghc-hetmet.git

[project @ 1999-02-04 15:20:32 by sof]
Document new -fwarn-type-defaults option.
---

diff --git a/ghc/docs/users_guide/using.vsgml b/ghc/docs/users_guide/using.vsgml
index 23055de..934ef56 100644
--- a/ghc/docs/users_guide/using.vsgml
+++ b/ghc/docs/users_guide/using.vsgml
@@ -397,6 +397,21 @@ mention of it in the export list.
 
 This option is on by default.
 
+<tag><tt>-fwarn-type-defaults</tt>:</tag>
+<nidx>-fwarn-type-defaults option</nidx>
+<nidx>defaulting mechanism, warning</nidx>
+
+Have the compiler warn/inform you where in your source the Haskell
+defaulting mechanism for numeric types kicks in. This is useful
+information when converting code from a context that assumed one
+default into one with another, e.g., the 'default default' for Haskell
+1.4 caused the otherwise unconstrained value <tt>1</tt> to be given
+the type <tt>Int</tt>, whereas Haskell 98 defaults it to
+<tt>Integer</tt>.  This may lead to differences in performance and
+behaviour, hence the usefulness of being non-silent about this.
+
+This warning is off by default.
+
 <tag>@-fwarn-missing-signatures@:</tag>
 <nidx>-fwarn-missing-signatures option</nidx>
 <nidx>type signatures, missing</nidx>