Forbid some empty separated lists in v2 (#667)

Part of #652

These are a bug-fixes along with regression tests added for each case,
we use a definition from v0/v1 for these.

crates/solidity/inputs/language/src/definition.rs

@@ -270,8 +270,7 @@ codegen_language_macros::compile!(Language(
                         Separated(
                             name = ImportDeconstructionFields,
                             separated = ImportDeconstructionField,
-                            separator = Comma,
-                            allow_empty = true
+                            separator = Comma
                         ),
                         Struct(
                             name = ImportDeconstructionField,
@@ -335,8 +334,7 @@ codegen_language_macros::compile!(Language(
                             name = UsingDeconstructionFields,
                             separated = UsingDeconstructionField,
                             separator = Comma,
-                            enabled = From("0.8.13"),
-                            allow_empty = true
+                            enabled = From("0.8.13")
                         ),
                         Struct(
                             name = UsingDeconstructionField,
@@ -2377,14 +2375,20 @@ codegen_language_macros::compile!(Language(
                         ),
                         Struct(
                             name = OverrideSpecifier,
+                            fields = (
+                                override_keyword = Required(Terminal([OverrideKeyword])),
+                                overridden = Optional(kind = NonTerminal(OverridePathsDeclaration))
+                            )
+                        ),
+                        Struct(
+                            name = OverridePathsDeclaration,
                             error_recovery = FieldsErrorRecovery(
                                 delimiters =
                                     FieldDelimiters(open = open_paren, close = close_paren)
                             ),
                             fields = (
-                                override_keyword = Required(Terminal([OverrideKeyword])),
                                 open_paren = Required(Terminal([OpenParen])),
-                                overridden = Optional(kind = NonTerminal(OverridePaths)),
+                                paths = Required(NonTerminal(OverridePaths)),
                                 close_paren = Required(Terminal([CloseParen]))
                             )
                         ),
@@ -2904,8 +2908,7 @@ codegen_language_macros::compile!(Language(
                         Separated(
                             name = TupleMembersDeconstruction,
                             separated = TupleMemberDeconstruction,
-                            separator = Comma,
-                            allow_empty = true
+                            separator = Comma
                         ),
                         Struct(
                             name = TupleMemberDeconstruction,

crates/solidity/testing/snapshots/cst_output/FunctionDefinition/overridden/generated/0.4.11-success.yml

@@ -0,0 +1,43 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ function some() public virtual override returns (uint256) {                      │ 0..59
+  2  │ 	return 1;                                                                       │ 60..70
+  3  │ }                                                                                │ 71..72
+
+Errors: []
+
+Tree:
+  - FunctionDefinition (Rule): # 0..73 "function some() public virtual override returns (u..."
+      - FunctionKeyword (Token): "function" # 0..8
+      - Identifier (Token): "some" # 9..13
+      - ParametersDeclaration (Rule): # 13..15 "()"
+          - OpenParen (Token): "(" # 13..14
+          - CloseParen (Token): ")" # 14..15
+      - FunctionAttributes (Rule): # 15..39 " public virtual override"
+          - PublicKeyword (Token): "public" # 16..22
+          - ModifierInvocation (Rule): # 22..30 " virtual"
+              - IdentifierPath (Rule): # 22..30 " virtual"
+                  - Identifier (Token): "virtual" # 23..30
+          - ModifierInvocation (Rule): # 30..39 " override"
+              - IdentifierPath (Rule): # 30..39 " override"
+                  - Identifier (Token): "override" # 31..39
+      - ReturnsDeclaration (Rule): # 39..57 " returns (uint256)"
+          - ReturnsKeyword (Token): "returns" # 40..47
+          - ParametersDeclaration (Rule): # 47..57 " (uint256)"
+              - OpenParen (Token): "(" # 48..49
+              - Parameters (Rule): # 49..56 "uint256"
+                  - Parameter (Rule): # 49..56 "uint256"
+                      - TypeName (Rule): # 49..56 "uint256"
+                          - UintKeyword (Token): "uint256" # 49..56
+              - CloseParen (Token): ")" # 56..57
+      - Block (Rule): # 57..73 " {\n\treturn 1;\n}\n"
+          - OpenBrace (Token): "{" # 58..59
+          - Statements (Rule): # 60..71 "\treturn 1;\n"
+              - ReturnStatement (Rule): # 60..71 "\treturn 1;\n"
+                  - ReturnKeyword (Token): "return" # 61..67
+                  - Expression (Rule): # 67..69 " 1"
+                      - DecimalNumberExpression (Rule): # 67..69 " 1"
+                          - DecimalLiteral (Token): "1" # 68..69
+                  - Semicolon (Token): ";" # 69..70
+          - CloseBrace (Token): "}" # 71..72

crates/solidity/testing/snapshots/cst_output/FunctionDefinition/overridden/generated/0.5.0-success.yml

@@ -0,0 +1,42 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ function some() public virtual override returns (uint256) {                      │ 0..59
+  2  │ 	return 1;                                                                       │ 60..70
+  3  │ }                                                                                │ 71..72
+
+Errors: []
+
+Tree:
+  - FunctionDefinition (Rule): # 0..73 "function some() public virtual override returns (u..."
+      - FunctionKeyword (Token): "function" # 0..8
+      - Identifier (Token): "some" # 9..13
+      - ParametersDeclaration (Rule): # 13..15 "()"
+          - OpenParen (Token): "(" # 13..14
+          - CloseParen (Token): ")" # 14..15
+      - FunctionAttributes (Rule): # 15..39 " public virtual override"
+          - PublicKeyword (Token): "public" # 16..22
+          - ModifierInvocation (Rule): # 22..30 " virtual"
+              - IdentifierPath (Rule): # 22..30 " virtual"
+                  - Identifier (Token): "virtual" # 23..30
+          - OverrideSpecifier (Rule): # 30..39 " override"
+              - OverrideKeyword (Token): "override" # 31..39
+      - ReturnsDeclaration (Rule): # 39..57 " returns (uint256)"
+          - ReturnsKeyword (Token): "returns" # 40..47
+          - ParametersDeclaration (Rule): # 47..57 " (uint256)"
+              - OpenParen (Token): "(" # 48..49
+              - Parameters (Rule): # 49..56 "uint256"
+                  - Parameter (Rule): # 49..56 "uint256"
+                      - TypeName (Rule): # 49..56 "uint256"
+                          - UintKeyword (Token): "uint256" # 49..56
+              - CloseParen (Token): ")" # 56..57
+      - Block (Rule): # 57..73 " {\n\treturn 1;\n}\n"
+          - OpenBrace (Token): "{" # 58..59
+          - Statements (Rule): # 60..71 "\treturn 1;\n"
+              - ReturnStatement (Rule): # 60..71 "\treturn 1;\n"
+                  - ReturnKeyword (Token): "return" # 61..67
+                  - Expression (Rule): # 67..69 " 1"
+                      - DecimalNumberExpression (Rule): # 67..69 " 1"
+                          - DecimalLiteral (Token): "1" # 68..69
+                  - Semicolon (Token): ";" # 69..70
+          - CloseBrace (Token): "}" # 71..72

crates/solidity/testing/snapshots/cst_output/FunctionDefinition/overridden/generated/0.6.0-success.yml

@@ -0,0 +1,40 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ function some() public virtual override returns (uint256) {                      │ 0..59
+  2  │ 	return 1;                                                                       │ 60..70
+  3  │ }                                                                                │ 71..72
+
+Errors: []
+
+Tree:
+  - FunctionDefinition (Rule): # 0..73 "function some() public virtual override returns (u..."
+      - FunctionKeyword (Token): "function" # 0..8
+      - Identifier (Token): "some" # 9..13
+      - ParametersDeclaration (Rule): # 13..15 "()"
+          - OpenParen (Token): "(" # 13..14
+          - CloseParen (Token): ")" # 14..15
+      - FunctionAttributes (Rule): # 15..39 " public virtual override"
+          - PublicKeyword (Token): "public" # 16..22
+          - VirtualKeyword (Token): "virtual" # 23..30
+          - OverrideSpecifier (Rule): # 30..39 " override"
+              - OverrideKeyword (Token): "override" # 31..39
+      - ReturnsDeclaration (Rule): # 39..57 " returns (uint256)"
+          - ReturnsKeyword (Token): "returns" # 40..47
+          - ParametersDeclaration (Rule): # 47..57 " (uint256)"
+              - OpenParen (Token): "(" # 48..49
+              - Parameters (Rule): # 49..56 "uint256"
+                  - Parameter (Rule): # 49..56 "uint256"
+                      - TypeName (Rule): # 49..56 "uint256"
+                          - UintKeyword (Token): "uint256" # 49..56
+              - CloseParen (Token): ")" # 56..57
+      - Block (Rule): # 57..73 " {\n\treturn 1;\n}\n"
+          - OpenBrace (Token): "{" # 58..59
+          - Statements (Rule): # 60..71 "\treturn 1;\n"
+              - ReturnStatement (Rule): # 60..71 "\treturn 1;\n"
+                  - ReturnKeyword (Token): "return" # 61..67
+                  - Expression (Rule): # 67..69 " 1"
+                      - DecimalNumberExpression (Rule): # 67..69 " 1"
+                          - DecimalLiteral (Token): "1" # 68..69
+                  - Semicolon (Token): ";" # 69..70
+          - CloseBrace (Token): "}" # 71..72

crates/solidity/testing/snapshots/cst_output/FunctionDefinition/overridden/input.sol

@@ -0,0 +1,3 @@
+function some() public virtual override returns (uint256) {
+	return 1;
+}

crates/solidity/testing/snapshots/cst_output/ImportDirective/destructure_import_empty/generated/0.4.11-failure.yml

@@ -0,0 +1,28 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ // Empty imports are not valid                                                   │ 0..30
+  2  │ import {} from "foo";                                                            │ 31..52
+
+Errors: # 1 total
+  - >
+    Error: Expected Identifier.
+       ╭─[crates/solidity/testing/snapshots/cst_output/ImportDirective/destructure_import_empty/input.sol:2:9]
+       │
+     2 │ import {} from "foo";
+       │         │ 
+       │         ╰─ Error occurred here.
+    ───╯
+
+Tree:
+  - ImportDirective (Rule): # 0..53 '// Empty imports are not valid\nimport {} from "foo...'
+      - LeadingTrivia (Rule): # 0..31 "// Empty imports are not valid\n"
+          - SingleLineComment (Trivia): "// Empty imports are not valid" # 0..30
+      - ImportKeyword (Token): "import" # 31..37
+      - DeconstructionImport (Rule): # 37..51 ' {} from "foo"'
+          - OpenBrace (Token): "{" # 38..39
+          - SKIPPED (Token): "" # 39..39
+          - CloseBrace (Token): "}" # 39..40
+          - FromKeyword (Token): "from" # 41..45
+          - AsciiStringLiteral (Token): '"foo"' # 46..51
+      - Semicolon (Token): ";" # 51..52

crates/solidity/testing/snapshots/cst_output/ImportDirective/destructure_import_empty/input.sol

@@ -0,0 +1,2 @@
+// Empty imports are not valid
+import {} from "foo";

crates/solidity/testing/snapshots/cst_output/TupleDeconstructionStatement/empty/generated/0.4.11-success.yml

@@ -0,0 +1,23 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ // TODO(#671): Tuple expressions can't be empty                                  │ 0..47
+  2  │ () = ();                                                                         │ 48..56
+
+Errors: []
+
+Tree:
+  - TupleDeconstructionStatement (Rule): # 0..57 "// TODO(#671): Tuple expressions can't be empty\n()..."
+      - LeadingTrivia (Rule): # 0..48 "// TODO(#671): Tuple expressions can't be empty\n"
+          - SingleLineComment (Trivia): "// TODO(#671): Tuple expressions can't be empty" # 0..47
+      - OpenParen (Token): "(" # 48..49
+      - TupleMembers (Rule): # 49..49
+          - TupleMember (Rule): [] # 49..49
+      - CloseParen (Token): ")" # 49..50
+      - Equal (Token): "=" # 51..52
+      - Expression (Rule): # 52..55 " ()"
+          - TupleExpression (Rule): # 52..55 " ()"
+              - OpenParen (Token): "(" # 53..54
+              - TupleValues (Rule): [] # 54..54
+              - CloseParen (Token): ")" # 54..55
+      - Semicolon (Token): ";" # 55..56

crates/solidity/testing/snapshots/cst_output/TupleDeconstructionStatement/empty/input.sol

@@ -0,0 +1,2 @@
+// TODO(#671): Tuple expressions can't be empty
+() = ();

crates/solidity/testing/snapshots/cst_output/UsingDirective/destructure_empty/generated/0.4.11-failure.yml

@@ -0,0 +1,23 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ // Empty using symbols list is not valid                                         │ 0..40
+  2  │ using {} for *;                                                                  │ 41..56
+
+Errors: # 1 total
+  - >
+    Error: Expected Identifier.
+       ╭─[crates/solidity/testing/snapshots/cst_output/UsingDirective/destructure_empty/input.sol:2:7]
+       │
+     2 │ using {} for *;
+       │       ────┬───  
+       │           ╰───── Error occurred here.
+    ───╯
+
+Tree:
+  - UsingDirective (Rule): # 0..57 "// Empty using symbols list is not valid\nusing {} ..."
+      - LeadingTrivia (Rule): # 0..41 "// Empty using symbols list is not valid\n"
+          - SingleLineComment (Trivia): "// Empty using symbols list is not valid" # 0..40
+      - UsingKeyword (Token): "using" # 41..46
+      - SKIPPED (Token): "{} for *" # 47..55
+      - Semicolon (Token): ";" # 55..56

crates/solidity/testing/snapshots/cst_output/UsingDirective/destructure_empty/generated/0.8.13-failure.yml

@@ -0,0 +1,28 @@
+# This file is generated automatically by infrastructure scripts. Please don't edit by hand.
+
+Source: >
+  1  │ // Empty using symbols list is not valid                                         │ 0..40
+  2  │ using {} for *;                                                                  │ 41..56
+
+Errors: # 1 total
+  - >
+    Error: Expected Identifier.
+       ╭─[crates/solidity/testing/snapshots/cst_output/UsingDirective/destructure_empty/input.sol:2:8]
+       │
+     2 │ using {} for *;
+       │        │ 
+       │        ╰─ Error occurred here.
+    ───╯
+
+Tree:
+  - UsingDirective (Rule): # 0..57 "// Empty using symbols list is not valid\nusing {} ..."
+      - LeadingTrivia (Rule): # 0..41 "// Empty using symbols list is not valid\n"
+          - SingleLineComment (Trivia): "// Empty using symbols list is not valid" # 0..40
+      - UsingKeyword (Token): "using" # 41..46
+      - UsingDirectiveDeconstruction (Rule): # 46..49 " {}"
+          - OpenBrace (Token): "{" # 47..48
+          - SKIPPED (Token): "" # 48..48
+          - CloseBrace (Token): "}" # 48..49
+      - ForKeyword (Token): "for" # 50..53
+      - Asterisk (Token): "*" # 54..55
+      - Semicolon (Token): ";" # 55..56

crates/solidity/testing/snapshots/cst_output/UsingDirective/destructure_empty/input.sol

@@ -0,0 +1,2 @@
+// Empty using symbols list is not valid
+using {} for *;

crates/solidity/testing/utils/src/cst_snapshots/mod.rs

@@ -126,6 +126,7 @@ fn write_node<W: Write>(
 
     let (node_value, node_comment) = if range.is_empty() {
         let preview = match node {
+            cst::Node::Rule(_) if !node.children().is_empty() => "",
             cst::Node::Rule(_) => " []",
             cst::Node::Token(_) => " \"\"",
         };