From 92c924e07dfef327509555c27a5478d9851ec9fa Mon Sep 17 00:00:00 2001
From: Thomas Miedema <thomasmiedema@gmail.com>
Date: Wed, 7 Oct 2015 20:36:54 -0500
Subject: [PATCH] Parser: revert some error messages to what they were before
7.10
Among doing other things, Phab:D201 (bc2289e13d9586be087bd8136943dc35a0130c88)
tried to improve the error messages thrown by the parser. For example a missing
else clause now prints "parse error in if statement: else clause empty" instead
of "parse error (possibly incorrect indentation or mismatched brackets)".
Some error messages got much worse however (see tests), and the result seems to
be a net negative. Although not entirely satisfactory, this commits therefore
reverts those parser changes.
Reviewed By: austin
Differential Revision: https://phabricator.haskell.org/D1309
GHC Trac Issues: #10498
---
compiler/parser/Parser.y | 31 -------------------
.../should_fail/ParserNoLambdaCase.stderr | 2 +-
testsuite/tests/parser/should_fail/T10498a.hs | 14 +++++++++
.../tests/parser/should_fail/T10498a.stderr | 2 ++
testsuite/tests/parser/should_fail/T10498b.hs | 7 +++++
.../tests/parser/should_fail/T10498b.stderr | 2 ++
testsuite/tests/parser/should_fail/all.T | 2 ++
.../parser/should_fail/readFail020.stderr | 3 +-
8 files changed, 29 insertions(+), 34 deletions(-)
create mode 100644 testsuite/tests/parser/should_fail/T10498a.hs
create mode 100644 testsuite/tests/parser/should_fail/T10498a.stderr
create mode 100644 testsuite/tests/parser/should_fail/T10498b.hs
create mode 100644 testsuite/tests/parser/should_fail/T10498b.stderr
diff --git a/compiler/parser/Parser.y b/compiler/parser/Parser.y
index 900620616b63..3ac0da32ccca 100644
--- a/compiler/parser/Parser.y
+++ b/compiler/parser/Parser.y
@@ -2067,37 +2067,6 @@ exp10 :: { LHsExpr RdrName }
-- hdaume: core annotation
| fexp { $1 }
- -- parsing error messages go below here
- | '\\' apat apats opt_asig '->' error {% parseErrorSDoc (combineLocs $1 $5) $ text
- "parse error in lambda: no expression after '->'"
- }
- | '\\' error {% parseErrorSDoc (getLoc $1) $ text
- "parse error: naked lambda expression '\'"
- }
- | 'let' binds 'in' error {% parseErrorSDoc (combineLocs $1 $2) $ text
- "parse error in let binding: missing expression after 'in'"
- }
- | 'let' binds error {% parseErrorSDoc (combineLocs $1 $2) $ text
- "parse error in let binding: missing required 'in'"
- }
- | 'let' error {% parseErrorSDoc (getLoc $1) $ text
- "parse error: naked let binding"
- }
- | 'if' exp optSemi 'then' exp optSemi
- 'else' error {% hintIf (combineLocs $1 $5) "else clause empty" }
- | 'if' exp optSemi 'then' exp optSemi error {% hintIf (combineLocs $1 $5) "missing required else clause" }
- | 'if' exp optSemi 'then' error {% hintIf (combineLocs $1 $2) "then clause empty" }
- | 'if' exp optSemi error {% hintIf (combineLocs $1 $2) "missing required then and else clauses" }
- | 'if' error {% hintIf (getLoc $1) "naked if statement" }
- | 'case' exp 'of' error {% parseErrorSDoc (combineLocs $1 $2) $ text
- "parse error in case statement: missing list after '->'"
- }
- | 'case' exp error {% parseErrorSDoc (combineLocs $1 $2) $ text
- "parse error in case statement: missing required 'of'"
- }
- | 'case' error {% parseErrorSDoc (getLoc $1) $ text
- "parse error: naked case statement"
- }
optSemi :: { ([Located a],Bool) }
: ';' { ([$1],True) }
| {- empty -} { ([],False) }
diff --git a/testsuite/tests/parser/should_fail/ParserNoLambdaCase.stderr b/testsuite/tests/parser/should_fail/ParserNoLambdaCase.stderr
index 5a3f1cc080ff..147c8fef9cce 100644
--- a/testsuite/tests/parser/should_fail/ParserNoLambdaCase.stderr
+++ b/testsuite/tests/parser/should_fail/ParserNoLambdaCase.stderr
@@ -1,2 +1,2 @@
-ParserNoLambdaCase.hs:3:5: parse error: naked lambda expression ''
+ParserNoLambdaCase.hs:3:6: parse error on input ‘case’
diff --git a/testsuite/tests/parser/should_fail/T10498a.hs b/testsuite/tests/parser/should_fail/T10498a.hs
new file mode 100644
index 000000000000..5a9656f25454
--- /dev/null
+++ b/testsuite/tests/parser/should_fail/T10498a.hs
@@ -0,0 +1,14 @@
+{-# LANGUAGE LambdaCase #-}
+module T10498a where
+
+-- ghc-7.10 would show the unhelpful error message:
+--
+-- T10498a.hs:10:5:
+-- parse error in if statement: missing required else clause
+
+foo =
+ if True
+ then
+ \case ->
+ 1 -> 2
+ else id
diff --git a/testsuite/tests/parser/should_fail/T10498a.stderr b/testsuite/tests/parser/should_fail/T10498a.stderr
new file mode 100644
index 000000000000..ed98bc112035
--- /dev/null
+++ b/testsuite/tests/parser/should_fail/T10498a.stderr
@@ -0,0 +1,2 @@
+
+T10498a.hs:12:15: parse error on input ‘->’
diff --git a/testsuite/tests/parser/should_fail/T10498b.hs b/testsuite/tests/parser/should_fail/T10498b.hs
new file mode 100644
index 000000000000..19b62af5aafa
--- /dev/null
+++ b/testsuite/tests/parser/should_fail/T10498b.hs
@@ -0,0 +1,7 @@
+module T10498b where
+
+-- ghc-7.10 would show the unhelpful error message:
+--
+-- T10498b.hs:7:5: parse error in if statement: naked if statement
+
+f = if module then True else False
diff --git a/testsuite/tests/parser/should_fail/T10498b.stderr b/testsuite/tests/parser/should_fail/T10498b.stderr
new file mode 100644
index 000000000000..c1e26a115608
--- /dev/null
+++ b/testsuite/tests/parser/should_fail/T10498b.stderr
@@ -0,0 +1,2 @@
+
+T10498b.hs:7:8: parse error on input ‘module’
diff --git a/testsuite/tests/parser/should_fail/all.T b/testsuite/tests/parser/should_fail/all.T
index 26d576757a5a..5c99f5be7abf 100644
--- a/testsuite/tests/parser/should_fail/all.T
+++ b/testsuite/tests/parser/should_fail/all.T
@@ -89,3 +89,5 @@ test('T8506', normal, compile_fail, [''])
test('T10196Fail1', normal, compile_fail, [''])
test('T10196Fail2', normal, compile_fail, [''])
test('T10196Fail3', expect_broken(10196), compile_fail, [''])
+test('T10498a', normal, compile_fail, [''])
+test('T10498b', normal, compile_fail, [''])
diff --git a/testsuite/tests/parser/should_fail/readFail020.stderr b/testsuite/tests/parser/should_fail/readFail020.stderr
index 0c00cdc79be2..0e3bde41da97 100644
--- a/testsuite/tests/parser/should_fail/readFail020.stderr
+++ b/testsuite/tests/parser/should_fail/readFail020.stderr
@@ -1,3 +1,2 @@
-readFail020.hs:3:5:
- parse error in let binding: missing required 'in'
+readFail020.hs:3:16: parse error on input ‘}’
--
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