Better error for definition followed by keyword

Fixes #18750
scala · Oct 24, 2023 · dc10902 · dc10902
1 parent 44a537b
commit dc10902
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diff --git a/compiler/src/dotty/tools/dotc/parsing/Parsers.scala b/compiler/src/dotty/tools/dotc/parsing/Parsers.scala
@@ -3598,6 +3598,8 @@ object Parsers {
      *            |  id {`,' id} `:' Type `=' `_' (deprecated in 3.x)
      */
     def patDefOrDcl(start: Offset, mods: Modifiers): Tree = atSpan(start, nameStart) {
+      if in.token != USCORE && isKeyword(in.token) then
+        syntaxError(ExpectedTokenButFound(IDENTIFIER, in.token), Span(in.offset))
       val first = pattern2(Location.InPattern)
       var lhs = first match {
         case id: Ident if in.token == COMMA =>

diff --git a/tests/neg/i18750.check b/tests/neg/i18750.check
@@ -0,0 +1,104 @@
+-- [E040] Syntax Error: tests/neg/i18750.scala:3:4 ---------------------------------------------------------------------
+3 |val do = 23 // error
+  |    ^
+  |    an identifier expected, but 'do' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'do' as identifier, you may put it in backticks: `do`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:4:4 ---------------------------------------------------------------------
+4 |val if = 23 // error
+  |    ^
+  |    an identifier expected, but 'if' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'if' as identifier, you may put it in backticks: `if`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:5:4 ---------------------------------------------------------------------
+5 |val val = 23 // error
+  |    ^
+  |    an identifier expected, but 'val' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'val' as identifier, you may put it in backticks: `val`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:6:7 ---------------------------------------------------------------------
+6 |val a, if = 23 // error
+  |       ^^
+  |       an identifier expected, but 'if' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'if' as identifier, you may put it in backticks: `if`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:8:4 ---------------------------------------------------------------------
+8 |def do; // error
+  |    ^^
+  |    an identifier expected, but 'do' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'do' as identifier, you may put it in backticks: `do`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:9:4 ---------------------------------------------------------------------
+9 |var do; // error
+  |    ^
+  |    an identifier expected, but 'do' found
+  |---------------------------------------------------------------------------------------------------------------------
+  | Explanation (enabled by `-explain`)
+  |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+  |
+  | If you want to use 'do' as identifier, you may put it in backticks: `do`.
+   ---------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:10:6 --------------------------------------------------------------------
+10 |class do; // error
+   |      ^^
+   |      an identifier expected, but 'do' found
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation (enabled by `-explain`)
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |
+   | If you want to use 'do' as identifier, you may put it in backticks: `do`.
+    --------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:11:7 --------------------------------------------------------------------
+11 |object if; // error // error
+   |       ^^
+   |       an identifier expected, but 'if' found
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation (enabled by `-explain`)
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |
+   | If you want to use 'if' as identifier, you may put it in backticks: `if`.
+    --------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:12:6 --------------------------------------------------------------------
+12 |trait else; // error
+   |      ^^^^
+   |      an identifier expected, but 'else' found
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation (enabled by `-explain`)
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |
+   | If you want to use 'else' as identifier, you may put it in backticks: `else`.
+    --------------------------------------------------------------------------------------------------------------------
+-- [E040] Syntax Error: tests/neg/i18750.scala:13:5 --------------------------------------------------------------------
+13 |type for; // error
+   |     ^^^
+   |     an identifier expected, but 'for' found
+   |--------------------------------------------------------------------------------------------------------------------
+   | Explanation (enabled by `-explain`)
+   |- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+   |
+   | If you want to use 'for' as identifier, you may put it in backticks: `for`.
+    --------------------------------------------------------------------------------------------------------------------
+-- [E161] Naming Error: tests/neg/i18750.scala:11:0 --------------------------------------------------------------------
+11 |object if; // error // error
+   |^
+   |<error> clashes with class <error> in tests/neg/i18750.scala; the two must be defined together
diff --git a/tests/neg/i18750.scala b/tests/neg/i18750.scala
@@ -0,0 +1,13 @@
+//> using options -explain
+
+val do = 23 // error
+val if = 23 // error
+val val = 23 // error
+val a, if = 23 // error
+
+def do; // error
+var do; // error
+class do; // error
+object if; // error // error
+trait else; // error
+type for; // error