chore: binderIdent normalization

fixes #1411

src/Init/Data/Nat/Linear.lean

@@ -338,7 +338,7 @@ theorem Poly.denote_mul (ctx : Context) (k : Nat) (p : Poly) : (p.mul k).denote
   by_cases h : k == 1 <;> simp [h]; simp [eq_of_beq h]
   induction p with
   | nil  => simp
-  | cons kv m ih => cases kv with | _ k' v => simp [ih]
+  | cons kv m ih => cases kv with | mk k' v => simp [ih]
 
 private theorem eq_of_not_blt_eq_true (h₁ : ¬ (Nat.blt x y = true)) (h₂ : ¬ (Nat.blt y x = true)) : x = y :=
   have h₁ : ¬ x < y := fun h => h₁ (Nat.blt_eq.mpr h)

src/Init/Tactics.lean

@@ -8,7 +8,7 @@ import Init.Notation
 
 namespace Lean
 
-syntax binderIdent := ident <|> "_"
+syntax binderIdent := ident <|> hole
 
 namespace Parser.Tactic
 /-- `with_annotate_state stx t` annotates the lexical range of `stx : Syntax` with the initial and final state of running tactic `t`. -/
@@ -34,7 +34,7 @@ For each hypothesis to be introduced, the remaining main goal's target type must
 -/
 syntax (name := intro) "intro " notFollowedBy("|") (colGt term:max)* : tactic
 /-- `intros x...` behaves like `intro x...`, but then keeps introducing (anonymous) hypotheses until goal is not of a function type. -/
-syntax (name := intros) "intros " (colGt (ident <|> "_"))* : tactic
+syntax (name := intros) "intros " (colGt (ident <|> hole))* : tactic
 /--
 `rename t => x` renames the most recent hypothesis whose type matches `t` (which may contain placeholders) to `x`,
 or fails if no such hypothesis could be found. -/
@@ -253,7 +253,7 @@ should be constructor applications of the same constructor.
 Given `h : a::b = c::d`, the tactic `injection h` adds two new hypothesis with types `a = c` and `b = d` to the main goal.
 The tactic `injection h with h₁ h₂` uses the names `h₁` and `h₂` to name the new hypotheses.
 -/
-syntax (name := injection) "injection " term (" with " (colGt (ident <|> "_"))+)? : tactic
+syntax (name := injection) "injection " term (" with " (colGt (ident <|> hole))+)? : tactic
 
 /-- `injections` applies `injection` to all hypotheses recursively
 (since `injection` can produce new hypotheses). Useful for destructing nested
@@ -354,7 +354,7 @@ macro (priority := high) "have'" x:ident " := " p:term : tactic => `(have' $x :
 /-- Similar to `let`, but using `refine'` -/
 macro "let' " d:letDecl : tactic => `(refine_lift' let $d:letDecl; ?_)
 
-syntax inductionAltLHS := "| " (("@"? ident) <|> "_") (ident <|> "_")*
+syntax inductionAltLHS := "| " (("@"? ident) <|> hole) (ident <|> hole)*
 syntax inductionAlt  := ppDedent(ppLine) inductionAltLHS+ " => " (hole <|> syntheticHole <|> tacticSeq)
 syntax inductionAlts := "with " (tactic)? withPosition( (colGe inductionAlt)+)
 /--

src/Lean/Elab/PreDefinition/WF/TerminationHint.lean

@@ -98,7 +98,7 @@ inductive TerminationWF where
 
 /-
 ```
-def terminationByElement   := leading_parser ppLine >> (ident <|> "_") >> many (ident <|> "_") >> " => " >> termParser >> optional ";"
+def terminationByElement   := leading_parser ppLine >> (ident <|> hole) >> many (ident <|> hole) >> " => " >> termParser >> optional ";"
 def terminationBy          := leading_parser ppLine >> "termination_by " >> many1chIndent terminationByElement
 ```
 -/

src/Lean/Elab/Tactic/Induction.lean

@@ -21,7 +21,7 @@ open Meta
 /-
   Given an `inductionAlt` of the form
   ```
-  syntax inductionAltLHS := "| " (group("@"? ident) <|> "_") (ident <|> "_")*
+  syntax inductionAltLHS := "| " (group("@"? ident) <|> hole) (ident <|> hole)*
   syntax inductionAlt  := ppDedent(ppLine) inductionAltLHS+ " => " (hole <|> syntheticHole <|> tacticSeq)
   ```
 -/

src/Lean/Parser/Command.lean

@@ -35,7 +35,7 @@ def terminationHint (p : Parser) := terminationHintMany p <|> terminationHint1 p
 def terminationByCore := leading_parser "termination_by' " >> terminationHint termParser
 def decreasingBy := leading_parser "decreasing_by " >> terminationHint Tactic.tacticSeq
 
-def terminationByElement   := leading_parser ppLine >> (ident <|> "_") >> many (ident <|> "_") >> " => " >> termParser >> optional ";"
+def terminationByElement   := leading_parser ppLine >> (ident <|> Term.hole) >> many (ident <|> Term.hole) >> " => " >> termParser >> optional ";"
 def terminationBy          := leading_parser ppLine >> "termination_by " >> many1Indent terminationByElement
 
 def terminationSuffix := optional (terminationBy <|> terminationByCore) >> optional decreasingBy

tests/lean/run/1411.lean

@@ -0,0 +1,6 @@
+namespace Lean
+syntax "foo " binderIdent : term
+example : Syntax → MacroM Syntax
+  | `(foo _) => `(_)
+  | `(foo $x:ident) => `($x:ident)
+  | _ => `(_)