Destructuring improvements (#3463)

10 files changed, 139 insertions, 52 deletions

diff --git a/tests/typ/compiler/backtracking.typ b/tests/typ/compiler/backtracking.typ
new file mode 100644
index 00000000..9c3ab8ec
--- /dev/null
+++ b/tests/typ/compiler/backtracking.typ
@@ -0,0 +1,33 @@
+// Ensure that parser backtracking doesn't lead to exponential time consumption.
+// If this regresses, the test suite will not terminate, which is a bit
+// unfortunate compared to a good error, but at least we know something is up.
+//
+// Ref: false
+
+---
+#{
+  let s = "(x: 1) => x"
+  let pat = "(x: {}) => 1 + x()"
+  for _ in range(50) {
+    s = pat.replace("{}", s)
+  }
+  test(eval(s)(), 51)
+}
+
+---
+#{
+  let s = "(x) = 1"
+  let pat = "(x: {_}) = 1"
+  for _ in range(100) {
+    s = pat.replace("_", s)
+  }
+  // Error: 8-9 cannot destructure integer
+  eval(s)
+}
+
+---
+// Test whitespace after memoized part.
+#( (x: () => 1 ) => 1 )
+//     -------
+//     This is memoized and we want to ensure that whitespace after this
+//     is handled correctly.
diff --git a/tests/typ/compiler/block.typ b/tests/typ/compiler/block.typ
index 0580acd2..48c9fefc 100644
--- a/tests/typ/compiler/block.typ
+++ b/tests/typ/compiler/block.typ
@@ -126,8 +126,7 @@
 
 // Should output `3`.
 #{
-  // Error: 6 expected identifier
-  // Error: 10 expected block
+  // Error: 7-10 expected pattern, found string
   for "v"
 
   // Error: 8 expected keyword `in`
diff --git a/tests/typ/compiler/call.typ b/tests/typ/compiler/call.typ
index e48eabfd..0c225a1c 100644
--- a/tests/typ/compiler/call.typ
+++ b/tests/typ/compiler/call.typ
@@ -75,8 +75,7 @@
 #f[1](2)
 
 ---
-// Error: 7 expected expression
-// Error: 8 expected expression
+// Error: 7-8 unexpected colon
 #func(:)
 
 // Error: 10-12 unexpected end of block comment
diff --git a/tests/typ/compiler/closure.typ b/tests/typ/compiler/closure.typ
index 85e9dbe2..ef4e7df0 100644
--- a/tests/typ/compiler/closure.typ
+++ b/tests/typ/compiler/closure.typ
@@ -171,26 +171,27 @@
 #let f((k: a, b), c: 3, (d,)) = (a, b, c, d)
 #test(f((k: 1, b: 2), (4,)), (1, 2, 3, 4))
 
-// Error: 22-23 duplicate parameter: a
-#let f((a: b), (c,), a) = none
-
-// Error: 8-14 expected identifier, found array
+// Error: 8-14 expected identifier, found destructuring pattern
 #let f((a, b): 0) = none
 
-// Error: 10-19 expected identifier, found destructuring pattern
+// Error: 10-19 expected pattern, found array
 #let f(..(a, b: c)) = none
 
-// Error: 10-16 expected identifier, found array
+// Error: 10-16 expected pattern, found array
 #let f(..(a, b)) = none
 
-// Error: 10-19 expected identifier, found destructuring pattern
-#let f(..(a, b: c)) = none
-
 ---
 // Error: 11-12 duplicate parameter: x
 #let f(x, x) = none
 
 ---
+// Error: 21 expected comma
+// Error: 22-23 expected pattern, found integer
+// Error: 24-25 unexpected plus
+// Error: 26-27 expected pattern, found integer
+#let f = (x: () => 1 2 + 3) => 4
+
+---
 // Error: 14-15 duplicate parameter: a
 // Error: 23-24 duplicate parameter: b
 // Error: 35-36 duplicate parameter: b
@@ -201,17 +202,18 @@
 #let f(a, ..a) = none
 
 ---
-// Error: 7-17 expected identifier, named pair or argument sink, found keyed pair
+// Error: 7-14 expected pattern, found string
 #((a, "named": b) => none)
 
 ---
-// Error: 10-15 expected identifier, found string
+// Error: 10-15 expected pattern, found string
 #let foo("key": b) = key
 
 ---
-// Error: 10-14 expected identifier, found `none`
+// Error: 10-14 expected pattern, found `none`
+// Hint: 10-14 keyword `none` is not allowed as an identifier; try `none_` instead
 #let foo(none: b) = key
 
 ---
-// Error: 11 expected comma
+// Error: 10-11 expected identifier, found underscore
 #let foo(_: 3) = none
diff --git a/tests/typ/compiler/dict.typ b/tests/typ/compiler/dict.typ
index 8a5be5cd..552b243c 100644
--- a/tests/typ/compiler/dict.typ
+++ b/tests/typ/compiler/dict.typ
@@ -110,7 +110,6 @@
 // Identified as dictionary due to initial colon.
 // The boolean key is allowed for now since it will only cause an error at the evaluation stage.
 // Error: 4-5 expected named or keyed pair, found integer
-// Error: 5 expected comma
 // Error: 17 expected expression
 #(:1 b:"", true:)
 
@@ -152,7 +151,7 @@
 
 ---
 // Error: 7-10 expected identifier, found group
-// Error: 12-14 expected identifier, found integer
+// Error: 12-14 expected pattern, found integer
 #let ((a): 10) = "world"
 
 ---
diff --git a/tests/typ/compiler/embedded-expr.typ b/tests/typ/compiler/embedded-expr.typ
index c95184e4..ee6e07f9 100644
--- a/tests/typ/compiler/embedded-expr.typ
+++ b/tests/typ/compiler/embedded-expr.typ
@@ -2,13 +2,13 @@
 // Ref: false
 
 ---
-// Error: 6-8 expected identifier, found keyword `as`
+// Error: 6-8 expected pattern, found keyword `as`
 // Hint: 6-8 keyword `as` is not allowed as an identifier; try `as_` instead
 #let as = 1 + 2
 
 ---
 #{
-  // Error: 7-9 expected identifier, found keyword `as`
+  // Error: 7-9 expected pattern, found keyword `as`
   // Hint: 7-9 keyword `as` is not allowed as an identifier; try `as_` instead
   let as = 10
 }
diff --git a/tests/typ/compiler/for.typ b/tests/typ/compiler/for.typ
index 64b5a1d4..392dd676 100644
--- a/tests/typ/compiler/for.typ
+++ b/tests/typ/compiler/for.typ
@@ -92,19 +92,24 @@
 
 ---
 // Destructuring without parentheses.
-// Error: 7 expected keyword `in`
-// Hint: 7 did you mean to use a destructuring pattern?
+// Error: 7-8 unexpected comma
+// Hint: 7-8 destructuring patterns must be wrapped in parentheses
 #for k, v in (a: 4, b: 5) {
   dont-care
 }
 
-// Error: 5 expected identifier
+// Error: 7-8 unexpected comma
+// Hint: 7-8 destructuring patterns must be wrapped in parentheses
+#for k, in () {}
+
+---
+// Error: 5 expected pattern
 #for
 
-// Error: 5 expected identifier
+// Error: 5 expected pattern
 #for//
 
-// Error: 6 expected identifier
+// Error: 6 expected pattern
 #{for}
 
 // Error: 7 expected keyword `in`
@@ -116,15 +121,15 @@
 // Error: 15 expected block
 #for v in iter
 
-// Error: 5 expected identifier
+// Error: 5 expected pattern
 #for
 v in iter {}
 
-// Error: 6 expected identifier
-// Error: 10 expected block
+// Error: 7-10 expected pattern, found string
+// Error: 16 expected block
 A#for "v" thing
 
-// Error: 5 expected identifier
+// Error: 6-9 expected pattern, found string
 #for "v" in iter {}
 
 // Error: 7 expected keyword `in`
diff --git a/tests/typ/compiler/let.typ b/tests/typ/compiler/let.typ
index 06f07394..411509ff 100644
--- a/tests/typ/compiler/let.typ
+++ b/tests/typ/compiler/let.typ
@@ -125,22 +125,22 @@ Three
 #test(a, 1)
 #test(b, 4)
 
-// Error: 10-11 at most one binding per identifier is allowed
+// Error: 10-11 duplicate binding: a
 #let (a, a) = (1, 2)
 
-// Error: 12-15 at most one destructuring sink is allowed
+// Error: 12-15 only one destructuring sink is allowed
 #let (..a, ..a) = (1, 2)
 
-// Error: 12-13 at most one binding per identifier is allowed
+// Error: 12-13 duplicate binding: a
 #let (a, ..a) = (1, 2)
 
-// Error: 13-14 at most one binding per identifier is allowed
+// Error: 13-14 duplicate binding: a
 #let (a: a, a) = (a: 1, b: 2)
 
-// Error: 13-20 expected identifier, found function call
+// Error: 13-20 expected pattern, found function call
 #let (a, b: b.at(0)) = (a: 1, b: 2)
 
-// Error: 7-14 expected identifier or destructuring sink, found function call
+// Error: 7-14 expected pattern, found function call
 #let (a.at(0),) = (1,)
 
 ---
@@ -148,7 +148,7 @@ Three
 #let (a, b, c) = (1, 2)
 
 ---
-// Error: 6-20 not enough elements to destructure
+// Error: 7-10 not enough elements to destructure
 #let (..a, b, c, d) = (1, 2)
 
 ---
@@ -194,14 +194,32 @@ Three
 #test(a, 1)
 
 ---
+// Ref: false
+// Nested destructuring.
+#let ((a, b), (key: c)) = ((1, 2), (key: 3))
+#test((a, b, c), (1, 2, 3))
+
+---
+// Keyed destructuring is not currently supported.
+// Error: 7-18 expected pattern, found string
+#let ("spacy key": val) = ("spacy key": 123)
+#val
+
+---
+// Keyed destructuring is not currently supported.
+#let x = "spacy key"
+// Error: 7-10 expected identifier, found group
+#let ((x): v) = ("spacy key": 123)
+
+---
 // Trailing placeholders.
 // Error: 10-11 not enough elements to destructure
 #let (a, _, _, _, _) = (1,)
 #test(a, 1)
 
 ---
-// Error: 10-13 expected identifier, found string
-// Error: 18-19 expected identifier, found integer
+// Error: 10-13 expected pattern, found string
+// Error: 18-19 expected pattern, found integer
 #let (a: "a", b: 2) = (a: 1, b: 2)
 
 ---
@@ -213,18 +231,17 @@ Three
 #let (a, b: b) = (a: 1)
 
 ---
-// Error: 7-11 cannot destructure named elements from an array
+// Error: 7-11 cannot destructure named pattern from an array
 #let (a: a, b) = (1, 2, 3)
 
 ---
-// Error: 5 expected identifier
+// Error: 5 expected pattern
 #let
 
-// Error: 6 expected identifier
+// Error: 6 expected pattern
 #{let}
 
-// Error: 5 expected identifier
-// Error: 5 expected semicolon or line break
+// Error: 6-9 expected pattern, found string
 #let "v"
 
 // Error: 7 expected semicolon or line break
@@ -233,8 +250,7 @@ Three
 // Error: 9 expected expression
 #let v =
 
-// Error: 5 expected identifier
-// Error: 5 expected semicolon or line break
+// Error: 6-9 expected pattern, found string
 #let "v" = 1
 
 // Terminated because expression ends.
@@ -246,7 +262,7 @@ Three
 // Error: 11-12 unclosed delimiter
 #let v5 = (1, 2 + ; Five
 
-// Error: 9-13 expected identifier, found boolean
+// Error: 9-13 expected pattern, found boolean
 #let (..true) = false
 
 ---
@@ -257,7 +273,7 @@ Three
 // Error: 2-3 unexpected underscore
 #_
 
-// Error: 8-9 unexpected underscore
+// Error: 8-9 expected expression, found underscore
 #lorem(_)
 
 // Error: 3-4 expected expression, found underscore
@@ -275,9 +291,11 @@ Three
 
 // Error: 15 expected expression
 #let func(x) =
+
 ---
 // Error: 12 expected equals sign
 #let (func)(x)
+
 ---
 // Error: 12 expected equals sign
 // Error: 15-15 expected semicolon or line break
diff --git a/tests/typ/compiler/ops.typ b/tests/typ/compiler/ops.typ
index 4d3b071f..e148dd19 100644
--- a/tests/typ/compiler/ops.typ
+++ b/tests/typ/compiler/ops.typ
@@ -274,6 +274,38 @@
 #test(b, 1)
 
 ---
+// Test comma placement in destructuring assignment.
+#let array = (1, 2, 3)
+#((key: array.at(1)) = (key: "hi"))
+#test(array, (1, "hi", 3))
+
+#let array = (1, 2, 3)
+#((array.at(1)) = ("hi"))
+#test(array, (1, "hi", 3))
+
+#let array = (1, 2, 3)
+#((array.at(1),) = ("hi",))
+#test(array, (1, "hi", 3))
+
+#let array = (1, 2, 3)
+#((array.at(1)) = ("hi",))
+#test(array, (1, ("hi",), 3))
+
+---
+// Test nested destructuring assignment.
+#let a
+#let b
+#let c
+#(((a, b), (key: c)) = ((1, 2), (key: 3)))
+#test((a, b, c), (1, 2, 3))
+
+---
+#let array = (1, 2, 3)
+// Error: 3-17 cannot destructure string
+#((array.at(1),) = ("hi"))
+#test(array, (1, ("hi",), 3))
+
+---
 // Error: 3-6 cannot mutate a constant: box
 #(box = 1)
 
diff --git a/tests/typ/compiler/spread.typ b/tests/typ/compiler/spread.typ
index f4864faf..23cd587b 100644
--- a/tests/typ/compiler/spread.typ
+++ b/tests/typ/compiler/spread.typ
@@ -61,11 +61,11 @@
 #test(f(1, 2, 3), 3)
 
 ---
-// Error: 13-19 cannot spread string
+// Error: 11-19 cannot spread string
 #calc.min(.."nope")
 
 ---
-// Error: 10-14 expected identifier, found boolean
+// Error: 10-14 expected pattern, found boolean
 #let f(..true) = none
 
 ---
@@ -90,11 +90,11 @@
 }
 
 ---
-// Error: 11-17 cannot spread dictionary into array
+// Error: 9-17 cannot spread dictionary into array
 #(1, 2, ..(a: 1))
 
 ---
-// Error: 5-11 cannot spread array into dictionary
+// Error: 3-11 cannot spread array into dictionary
 #(..(1, 2), a: 1)
 
 ---