Fix typescript compile errors

[nicholascapo]

After upgrading from v0.10.0 to v2.0.1 in a typescript project, tsc gives the following errors:

node_modules/execa/index.d.ts:116:61 - error TS1005: ';' expected.

116  	readonly stdio?: 'pipe' | 'ignore' | 'inherit' | readonly StdioOption[];
     	                                                          ~~~~~~~~~~~

node_modules/execa/index.d.ts:116:73 - error TS1011: An element access expression should take an argument.

116  	readonly stdio?: 'pipe' | 'ignore' | 'inherit' | readonly StdioOption[];
     	                                                                      

node_modules/execa/index.d.ts:123:3 - error TS1128: Declaration or statement expected.

123  	readonly detached?: boolean;
     	~~~~~~~~

node_modules/execa/index.d.ts:123:21 - error TS1109: Expression expected.

123  	readonly detached?: boolean;
     	                  ~

node_modules/execa/index.d.ts:128:3 - error TS1128: Declaration or statement expected.

128  	readonly uid?: number;
     	~~~~~~~~

node_modules/execa/index.d.ts:128:16 - error TS1109: Expression expected.

128  	readonly uid?: number;
     	             ~

node_modules/execa/index.d.ts:133:3 - error TS1128: Declaration or statement expected.

133  	readonly gid?: number;
     	~~~~~~~~

node_modules/execa/index.d.ts:133:16 - error TS1109: Expression expected.

133  	readonly gid?: number;
     	             ~

node_modules/execa/index.d.ts:145:3 - error TS1128: Declaration or statement expected.

145  	readonly shell?: boolean | string;
     	~~~~~~~~

node_modules/execa/index.d.ts:145:18 - error TS1109: Expression expected.

145  	readonly shell?: boolean | string;
     	               ~

node_modules/execa/index.d.ts:152:3 - error TS1128: Declaration or statement expected.

152  	readonly encoding?: EncodingType;
     	~~~~~~~~

node_modules/execa/index.d.ts:152:21 - error TS1109: Expression expected.

152  	readonly encoding?: EncodingType;
     	                  ~

node_modules/execa/index.d.ts:159:3 - error TS1128: Declaration or statement expected.

159  	readonly timeout?: number;
     	~~~~~~~~

node_modules/execa/index.d.ts:159:20 - error TS1109: Expression expected.

159  	readonly timeout?: number;
     	                 ~

node_modules/execa/index.d.ts:166:3 - error TS1128: Declaration or statement expected.

166  	readonly maxBuffer?: number;
     	~~~~~~~~

node_modules/execa/index.d.ts:166:22 - error TS1109: Expression expected.

166  	readonly maxBuffer?: number;
     	                   ~

node_modules/execa/index.d.ts:173:3 - error TS1128: Declaration or statement expected.

173  	readonly killSignal?: string | number;
     	~~~~~~~~

node_modules/execa/index.d.ts:173:23 - error TS1109: Expression expected.

173  	readonly killSignal?: string | number;
     	                    ~

node_modules/execa/index.d.ts:180:3 - error TS1128: Declaration or statement expected.

180  	readonly windowsVerbatimArguments?: boolean;
     	~~~~~~~~

node_modules/execa/index.d.ts:180:37 - error TS1109: Expression expected.

180  	readonly windowsVerbatimArguments?: boolean;
     	                                  ~

node_modules/execa/index.d.ts:329:1 - error TS1128: Declaration or statement expected.

329 }
    ~

node_modules/execa/index.d.ts:367:24 - error TS1005: ',' expected.

367  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:367:30 - error TS1005: ',' expected.

367  	arguments?: readonly string[],
     	                           ~

node_modules/execa/index.d.ts:372:24 - error TS1005: ',' expected.

372  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:372:30 - error TS1005: ',' expected.

372  	arguments?: readonly string[],
     	                           ~

node_modules/execa/index.d.ts:391:24 - error TS1005: ',' expected.

391  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:391:30 - error TS1005: ',' expected.

391  	arguments?: readonly string[],
     	                           ~

node_modules/execa/index.d.ts:396:24 - error TS1005: ',' expected.

396  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:396:30 - error TS1005: ',' expected.

396  	arguments?: readonly string[],
     	                           ~

node_modules/execa/index.d.ts:452:24 - error TS1005: ',' expected.

452  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:452:30 - error TS1005: ',' expected.

452  	arguments?: readonly string[],
     	                           ~

node_modules/execa/index.d.ts:457:24 - error TS1005: ',' expected.

457  	arguments?: readonly string[],
     	                     ~~~~~~

node_modules/execa/index.d.ts:457:30 - error TS1005: ',' expected.

457  	arguments?: readonly string[],
     	                           ~
Found 33 errors.

I tried moving the readonly modifiers to the start of those lines, but then got this (possibly helpful) error message from the linter:

index.d.ts:367:2
✖  367:2  A parameter property is only allowed in a constructor implementation.  
✖  372:2  A parameter property is only allowed in a constructor implementation.  
✖  391:2  A parameter property is only allowed in a constructor implementation.  
✖  396:2  A parameter property is only allowed in a constructor implementation.  
✖  452:2  A parameter property is only allowed in a constructor implementation.  
✖  457:2  A parameter property is only allowed in a constructor implementation.  

[ehmicky]

Hi @nicholascapo, thanks for this PR.

For extra background, could you please tell us:

• your TypeScript version
• your tsconfig.json or tsc CLI options
• your @types/node version

I might be wrong but TypeScript 3.4 introduced several changes with the readonly keyword.

[nicholascapo]

Well darn!

I tested with Typescript v3.1.1 and v3.2.4
I didn't actually have @types/node installed, after adding it the errors went away!

Thanks for the help, sorry for the noise 😄

[ehmicky]

Yes I just checked and the errors above appear with TypeScript <3.4.

Thanks for reporting though.