fix: support non-null expressions in more places

Fixes TyrealHu/acorn-typescript#64
Fixes sveltejs/svelte#13409

Author: dummdidumm

.changeset/yummy-dogs-dance.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/acorn-typescript': patch
+---
+
+fix: support non-null expressions in more places

__test__/__snapshot__/expression/variables.ts

@@ -5011,6 +5011,331 @@ const VariablesTypeSnapshot = {
 			}
 		],
 		sourceType: 'module'
+	},
+	NonNullAssignment: {
+		type: 'Program',
+		start: 0,
+		end: 44,
+		loc: {
+			start: {
+				line: 1,
+				column: 0,
+				index: 0
+			},
+			end: {
+				line: 3,
+				column: 7,
+				index: 44
+			}
+		},
+		body: [
+			{
+				type: 'VariableDeclaration',
+				start: 0,
+				end: 29,
+				loc: {
+					start: {
+						line: 1,
+						column: 0,
+						index: 0
+					},
+					end: {
+						line: 1,
+						column: 29,
+						index: 29
+					}
+				},
+				declarations: [
+					{
+						type: 'VariableDeclarator',
+						start: 4,
+						end: 29,
+						loc: {
+							start: {
+								line: 1,
+								column: 4,
+								index: 4
+							},
+							end: {
+								line: 1,
+								column: 29,
+								index: 29
+							}
+						},
+						id: {
+							type: 'Identifier',
+							start: 4,
+							end: 25,
+							loc: {
+								start: {
+									line: 1,
+									column: 4,
+									index: 4
+								},
+								end: {
+									line: 1,
+									column: 25,
+									index: 25
+								}
+							},
+							name: 'a',
+							typeAnnotation: {
+								type: 'TSTypeAnnotation',
+								start: 5,
+								end: 25,
+								loc: {
+									start: {
+										line: 1,
+										column: 5,
+										index: 5
+									},
+									end: {
+										line: 1,
+										column: 25,
+										index: 25
+									}
+								},
+								typeAnnotation: {
+									type: 'TSUnionType',
+									start: 7,
+									end: 25,
+									loc: {
+										start: {
+											line: 1,
+											column: 7,
+											index: 7
+										},
+										end: {
+											line: 1,
+											column: 25,
+											index: 25
+										}
+									},
+									types: [
+										{
+											type: 'TSNumberKeyword',
+											start: 7,
+											end: 13,
+											loc: {
+												start: {
+													line: 1,
+													column: 7,
+													index: 7
+												},
+												end: {
+													line: 1,
+													column: 13,
+													index: 13
+												}
+											}
+										},
+										{
+											type: 'TSUndefinedKeyword',
+											start: 16,
+											end: 25,
+											loc: {
+												start: {
+													line: 1,
+													column: 16,
+													index: 16
+												},
+												end: {
+													line: 1,
+													column: 25,
+													index: 25
+												}
+											}
+										}
+									]
+								}
+							}
+						},
+						init: {
+							type: 'Literal',
+							start: 28,
+							end: 29,
+							loc: {
+								start: {
+									line: 1,
+									column: 28,
+									index: 28
+								},
+								end: {
+									line: 1,
+									column: 29,
+									index: 29
+								}
+							},
+							value: 1,
+							raw: '1'
+						}
+					}
+				],
+				kind: 'let'
+			},
+			{
+				type: 'ExpressionStatement',
+				start: 30,
+				end: 36,
+				loc: {
+					start: {
+						line: 2,
+						column: 0,
+						index: 30
+					},
+					end: {
+						line: 2,
+						column: 6,
+						index: 36
+					}
+				},
+				expression: {
+					type: 'AssignmentExpression',
+					start: 30,
+					end: 36,
+					loc: {
+						start: {
+							line: 2,
+							column: 0,
+							index: 30
+						},
+						end: {
+							line: 2,
+							column: 6,
+							index: 36
+						}
+					},
+					operator: '=',
+					left: {
+						type: 'Identifier',
+						start: 30,
+						end: 31,
+						loc: {
+							start: {
+								line: 2,
+								column: 0,
+								index: 30
+							},
+							end: {
+								line: 2,
+								column: 1,
+								index: 31
+							}
+						},
+						name: 'a'
+					},
+					right: {
+						type: 'Literal',
+						start: 35,
+						end: 36,
+						loc: {
+							start: {
+								line: 2,
+								column: 5,
+								index: 35
+							},
+							end: {
+								line: 2,
+								column: 6,
+								index: 36
+							}
+						},
+						value: 2,
+						raw: '2'
+					}
+				}
+			},
+			{
+				type: 'ExpressionStatement',
+				start: 37,
+				end: 44,
+				loc: {
+					start: {
+						line: 3,
+						column: 0,
+						index: 37
+					},
+					end: {
+						line: 3,
+						column: 7,
+						index: 44
+					}
+				},
+				expression: {
+					type: 'AssignmentExpression',
+					start: 37,
+					end: 44,
+					loc: {
+						start: {
+							line: 3,
+							column: 0,
+							index: 37
+						},
+						end: {
+							line: 3,
+							column: 7,
+							index: 44
+						}
+					},
+					operator: '+=',
+					left: {
+						type: 'TSNonNullExpression',
+						start: 37,
+						end: 39,
+						loc: {
+							start: {
+								line: 3,
+								column: 0,
+								index: 37
+							},
+							end: {
+								line: 3,
+								column: 2,
+								index: 39
+							}
+						},
+						expression: {
+							type: 'Identifier',
+							start: 37,
+							end: 38,
+							loc: {
+								start: {
+									line: 3,
+									column: 0,
+									index: 37
+								},
+								end: {
+									line: 3,
+									column: 1,
+									index: 38
+								}
+							},
+							name: 'a'
+						}
+					},
+					right: {
+						type: 'Literal',
+						start: 43,
+						end: 44,
+						loc: {
+							start: {
+								line: 3,
+								column: 6,
+								index: 43
+							},
+							end: {
+								line: 3,
+								column: 7,
+								index: 44
+							}
+						},
+						value: 3,
+						raw: '3'
+					}
+				}
+			}
+		],
+		sourceType: 'module'
 	}
 };
 

__test__/expression/variables.test.ts

@@ -197,4 +197,12 @@ describe('variables declaration', () => {
 
 		equalNode(node, VariablesTypeSnapshot.IssueFile43);
 	});
+
+	it('TSNonNullExpression', () => {
+		const node = parseSource(
+			generateSource([`let a: number | undefined = 1`, `a! = 2`, `a! += 3`])
+		);
+
+		equalNode(node, VariablesTypeSnapshot.NonNullAssignment);
+	});
 });

src/index.ts

@@ -2592,6 +2592,9 @@ function tsPlugin(options?: {
 			}
 
 			checkLValSimple(expr: any, bindingType: any = acornScope.BIND_NONE, checkClashes?: any) {
+				if (expr.type === 'TSNonNullExpression') {
+					expr = expr.expression;
+				}
 				return super.checkLValSimple(expr, bindingType, checkClashes);
 			}