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feat(eslint-plugin): [no-shadow] add shadowed variable location to the error message #5183

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merged 2 commits into from
Jun 26, 2022
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feat(eslint-plugin): [no-shadow] add shadowed variable location to the error message #5183

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feat(eslint-plugin): [no-shadow] add shadowed variable location to th…
bradzacher Jun 13, 2022
a58c221
review fix
bradzacher Jun 26, 2022
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49 changes: 43 additions & 6 deletions packages/eslint-plugin/src/rules/no-shadow.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ import {
} from '@typescript-eslint/scope-manager';
import * as util from '../util';

type MessageIds = 'noShadow';
type MessageIds = 'noShadow' | 'noShadowGlobal';
type Options = [
{
allow?: string[];
Expand Down Expand Up @@ -64,7 +64,9 @@ export default util.createRule<Options, MessageIds>({
},
],
messages: {
noShadow: "'{{name}}' is already declared in the upper scope.",
noShadow:
"'{{name}}' is already declared in the upper scope on line {{shadowedLine}} column {{shadowedColumn}}.",
noShadowGlobal: "'{{name}}' is already a global variable.",
},
},
defaultOptions: [
Expand Down Expand Up @@ -517,6 +519,28 @@ export default util.createRule<Options, MessageIds>({
);
}

/**
* Get declared line and column of a variable.
* @param variable The variable to get.
* @returns The declared line and column of the variable.
*/
function getDeclaredLocation(
variable: TSESLint.Scope.Variable,
): { global: true } | { global: false; line: number; column: number } {
const identifier = variable.identifiers[0];
if (identifier) {
return {
global: false,
line: identifier.loc.start.line,
column: identifier.loc.start.column + 1,
};
} else {
return {
global: true,
};
}
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Nitty nit: could be simplified to return identifier ? { ... } : { ... };.

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you really do love your ternaries 😄
personally I prefer to only use ternaries for when I want an expression.
I find in this case where I can do everything with statements - using an if statement is clearer and cleaner.

}

/**
* Checks the current context for shadowed variables.
* @param {Scope} scope Fixme
Expand Down Expand Up @@ -595,12 +619,25 @@ export default util.createRule<Options, MessageIds>({
) &&
!(options.hoist !== 'all' && isInTdz(variable, shadowed))
) {
const location = getDeclaredLocation(shadowed);

context.report({
node: variable.identifiers[0],
messageId: 'noShadow',
data: {
name: variable.name,
},
...(location.global
? {
messageId: 'noShadowGlobal',
data: {
name: variable.name,
},
}
: {
messageId: 'noShadow',
data: {
name: variable.name,
shadowedLine: location.line,
shadowedColumn: location.column,
},
}),
});
}
}
Expand Down
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