[commit: ghc] master: renamer: fix trac issue #9778 (87160c1)

git at git.haskell.org git at git.haskell.org
Sat Dec 6 00:35:44 UTC 2014


Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/87160c1a5e5c742de176b29d8c3a596fba0983cf/ghc

>---------------------------------------------------------------

commit 87160c1a5e5c742de176b29d8c3a596fba0983cf
Author: Carlos Tomé <carlostome1990 at gmail.com>
Date:   Fri Dec 5 14:36:55 2014 -0600

    renamer: fix trac issue #9778
    
    Summary: Added flag -fwarn-unticked-promoted-constructors
    
    Test Plan: test T9778 under tests/rename/should_compile
    
    Reviewers: jstolarek, simonpj, austin
    
    Reviewed By: jstolarek, simonpj, austin
    
    Subscribers: simonpj, goldfire, jstolarek, thomie, carter
    
    Differential Revision: https://phabricator.haskell.org/D534
    
    GHC Trac Issues: #9778


>---------------------------------------------------------------

87160c1a5e5c742de176b29d8c3a596fba0983cf
 compiler/main/DynFlags.hs                          |  3 +++
 compiler/rename/RnEnv.hs                           | 12 ++++++++++-
 docs/users_guide/flags.xml                         |  7 +++++++
 docs/users_guide/using.xml                         | 24 ++++++++++++++++++++++
 testsuite/tests/rename/should_compile/T9778.hs     |  8 ++++++++
 testsuite/tests/rename/should_compile/T9778.stderr |  3 +++
 testsuite/tests/rename/should_compile/all.T        |  1 +
 7 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index aaa52fe..5f277db 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -505,6 +505,7 @@ data WarningFlag =
    | Opt_WarnTypedHoles
    | Opt_WarnPartialTypeSignatures
    | Opt_WarnMissingExportedSigs
+   | Opt_WarnUntickedPromotedConstructors
    deriving (Eq, Show, Enum)
 
 data Language = Haskell98 | Haskell2010
@@ -2835,6 +2836,8 @@ fWarningFlags = [
   flagSpec "warn-unsupported-calling-conventions"
                                          Opt_WarnUnsupportedCallingConventions,
   flagSpec "warn-unsupported-llvm-version"    Opt_WarnUnsupportedLlvmVersion,
+  flagSpec "warn-unticked-promoted-constructors"
+                                         Opt_WarnUntickedPromotedConstructors,
   flagSpec "warn-unused-binds"                Opt_WarnUnusedBinds,
   flagSpec "warn-unused-do-bind"              Opt_WarnUnusedDoBind,
   flagSpec "warn-unused-imports"              Opt_WarnUnusedImports,
diff --git a/compiler/rename/RnEnv.hs b/compiler/rename/RnEnv.hs
index 0cea309..eeffe17 100644
--- a/compiler/rename/RnEnv.hs
+++ b/compiler/rename/RnEnv.hs
@@ -699,7 +699,10 @@ lookup_demoted rdr_name
        ; case mb_demoted_name of
            Nothing -> reportUnboundName rdr_name
            Just demoted_name
-             | data_kinds -> return demoted_name
+             | data_kinds ->
+             do { whenWOptM Opt_WarnUntickedPromotedConstructors $
+                  addWarn (untickedPromConstrWarn demoted_name)
+                ; return demoted_name }
              | otherwise  -> unboundNameX WL_Any rdr_name suggest_dk }
 
   | otherwise
@@ -707,6 +710,13 @@ lookup_demoted rdr_name
 
   where
     suggest_dk = ptext (sLit "A data constructor of that name is in scope; did you mean DataKinds?")
+    untickedPromConstrWarn name =
+      text "Unticked promoted constructor" <> colon <+> quotes (ppr name) <> dot
+      $$
+      hsep [ text "Use"
+           , quotes (char '\'' <> ppr name)
+           , text "instead of"
+           , quotes (ppr name) <> dot ]
 
 {-
 Note [Demotion]
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index 9ddd271..6ba0c6f 100644
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -1570,6 +1570,13 @@
           </row>
 
           <row>
+            <entry><option>-fwarn-unticked-promoted-constructors</option></entry>
+            <entry>warn if promoted constructors are not ticked </entry>
+            <entry>dynamic</entry>
+            <entry><option>-fno-warn-unticked-promoted-constructors</option></entry>
+          </row>
+
+          <row>
             <entry><option>-fwarn-unused-binds</option></entry>
             <entry>warn about bindings that are unused</entry>
             <entry>dynamic</entry>
diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml
index 396af6c..8006fff 100644
--- a/docs/users_guide/using.xml
+++ b/docs/users_guide/using.xml
@@ -1796,6 +1796,30 @@ f "2"    = 2
       </varlistentry>
 
       <varlistentry>
+        <term><option>-fwarn-unticked-promoted-constructors</option>:</term>
+        <listitem>
+          <indexterm><primary><option>-fwarn-unticked-promoted-constructors</option></primary></indexterm>
+          <indexterm><primary>promoted constructor, warning</primary></indexterm>
+          <para>Warn if a promoted data constructor is used without a tick preceding it's name.
+          </para>
+          <para>For example:
+          </para>
+<programlisting>
+data Nat = Succ Nat | Zero
+
+data Vec n s where
+  Nil  :: Vec Zero a
+  Cons :: a -> Vec n a -> Vec (Succ n) a
+</programlisting>
+            <para> Will raise two warnings because <function>Zero</function>
+            and <function>Succ</function> are not written as <function>'Zero</function> and
+            <function>'Succ</function>.
+            </para>
+            <para>This warning is off by default.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
         <term><option>-fwarn-unused-binds</option>:</term>
         <listitem>
           <indexterm><primary><option>-fwarn-unused-binds</option></primary></indexterm>
diff --git a/testsuite/tests/rename/should_compile/T9778.hs b/testsuite/tests/rename/should_compile/T9778.hs
new file mode 100644
index 0000000..5b32f67
--- /dev/null
+++ b/testsuite/tests/rename/should_compile/T9778.hs
@@ -0,0 +1,8 @@
+{-# LANGUAGE DataKinds #-}
+{-# LANGUAGE GADTs #-}
+module T9778 where
+
+data T = A | B
+
+data G a where
+  C :: G A
diff --git a/testsuite/tests/rename/should_compile/T9778.stderr b/testsuite/tests/rename/should_compile/T9778.stderr
new file mode 100644
index 0000000..3d2e40f
--- /dev/null
+++ b/testsuite/tests/rename/should_compile/T9778.stderr
@@ -0,0 +1,3 @@
+ T9778.hs:8:10: Warning:
+     Unticked promoted constructor: ‘A’.
+         Use ‘'A’ instead of ‘A’.
diff --git a/testsuite/tests/rename/should_compile/all.T b/testsuite/tests/rename/should_compile/all.T
index 7185fba..9265f18 100644
--- a/testsuite/tests/rename/should_compile/all.T
+++ b/testsuite/tests/rename/should_compile/all.T
@@ -218,3 +218,4 @@ test('T7969',
      ['$MAKE -s --no-print-directory T7969'])
 test('T9127', normal, compile, [''])
 test('T4426', normal, compile, [''])
+test('T9778', normal, compile, ['-fwarn-unticked-promoted-constructors'])



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