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Merged
gh-worker-dd-mergequeue-cf854d merged 1 commit into from
May 12, 2026
+80 −28
Merged

fix(live-debugger): exclude params from locals in instrumented code #335

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77 changes: 60 additions & 17 deletions packages/plugins/live-debugger/src/transform/index.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -257,27 +257,33 @@ describe('transformCode', () => {
});

describe('hoisted variable capture', () => {
it('should generate entry and exit helper functions', () => {
it('should generate args and locals helpers', () => {
const result = transformCode({
...BASE_OPTIONS,
code: 'function f(a, b) { const c = 1; return a + b + c; }',
});

// Entry helper captures params only
expect(result.code).toMatch(/\$dd_e\d+ = \(\) => \(\{a, b\}\)/);
// Exit helper captures params + locals
expect(result.code).toMatch(/\$dd_l\d+ = \(\) => \(\{a, b, c\}\)/);
expect(result.code).toMatch(/\$dd_l\d+ = \(\) => \(\{c\}\)/);
});

it('should emit a single shared helper when entry and exit vars are identical', () => {
it('should omit the locals helper when there are no locals', () => {
const result = transformCode({
...BASE_OPTIONS,
code: 'function f(a, b) { return a + b; }',
});

// Only the entry helper should be emitted
expect(result.code).toMatch(/\$dd_e\d+ = \(\) => \(\{a, b\}\)/);
// No exit helper should be present
expect(result.code).not.toMatch(/\$dd_l\d+/);
});

it('should omit both helpers when there are no params and no locals', () => {
const result = transformCode({
...BASE_OPTIONS,
code: 'function f() { return 1; }',
});

expect(result.code).not.toMatch(/\$dd_e\d+/);
expect(result.code).not.toMatch(/\$dd_l\d+/);
});
});
Expand Down Expand Up @@ -668,6 +674,43 @@ describe('transformCode', () => {
return lines.map((s) => s.trimStart()).join('\n');
}

it('should produce the expected output for a function with no arguments', () => {
const result = transformCode({
...BASE_OPTIONS,
code: 'function getTime() { return Date.now(); }',
});

expect(normalizeCode(result.code)).toBe(
normalizeCode(
"function getTime() {const $dd_p0 = $dd_probes('src/utils.ts;getTime');",
' try {',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this); return ($dd_rv0 = Date.now(), $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this) : $dd_rv0); ',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this); throw e; }',
'}',
),
);
});

it('should produce the expected output for a function with no arguments but with locals', () => {
const result = transformCode({
...BASE_OPTIONS,
code: 'function getTime() { const now = Date.now(); return now; }',
});

expect(normalizeCode(result.code)).toBe(
normalizeCode(
"function getTime() {const $dd_p0 = $dd_probes('src/utils.ts;getTime');",
' try {',
' const $dd_l0 = () => ({now});',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this); const now = Date.now(); return ($dd_rv0 = now, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, undefined, $dd_l0()) : $dd_rv0); ',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this); throw e; }',
'}',
),
);
});

it('should produce the expected output for a function with a single return', () => {
const result = transformCode({
...BASE_OPTIONS,
Expand All @@ -680,7 +723,7 @@ describe('transformCode', () => {
' const $dd_e0 = () => ({a, b});',
' try {',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); return ($dd_rv0 = a + b, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0()) : $dd_rv0); ',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); return ($dd_rv0 = a + b, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0); ',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'}',
),
Expand All @@ -698,7 +741,7 @@ describe('transformCode', () => {
"function add(a, b) {const $dd_p0 = $dd_probes('src/utils.ts;add');",
' const $dd_e0 = () => ({a, b});',
' try {',
' const $dd_l0 = () => ({a, b, sum});',
' const $dd_l0 = () => ({sum});',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); const sum = a + b; return ($dd_rv0 = sum, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_l0()) : $dd_rv0); ',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
Expand All @@ -721,7 +764,7 @@ describe('transformCode', () => {
' try {',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());',
' const $dd_rv0 = x * 2;',
' if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0());',
' if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0());',
' return $dd_rv0;',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'};',
Expand All @@ -743,7 +786,7 @@ describe('transformCode', () => {
' try {',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());',
' const $dd_rv0 = {key: x};',
' if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0());',
' if ($dd_p0) $dd_return($dd_p0, $dd_rv0, this, $dd_e0());',
' return $dd_rv0;',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'};',
Expand All @@ -764,7 +807,7 @@ describe('transformCode', () => {
' try {',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); console.log(msg); ',
' if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0(), $dd_e0());',
' if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0());',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'}',
),
Expand All @@ -783,7 +826,7 @@ describe('transformCode', () => {
' const $dd_e0 = () => ({x});',
' try {',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); if (x < 0) { return ($dd_rv0 = -x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0()) : $dd_rv0); } return ($dd_rv0 = x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0()) : $dd_rv0); ',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); if (x < 0) { return ($dd_rv0 = -x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0); } return ($dd_rv0 = x, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0); ',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'}',
),
Expand All @@ -802,8 +845,8 @@ describe('transformCode', () => {
' const $dd_e0 = () => ({x});',
' try {',
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); if (!x) { if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0(), $dd_e0()); return; } console.log(x); ',
' if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0(), $dd_e0());',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0()); if (!x) { if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0()); return; } console.log(x); ',
' if ($dd_p0) $dd_return($dd_p0, undefined, this, $dd_e0());',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
'}',
),
Expand Down Expand Up @@ -832,9 +875,9 @@ describe('transformCode', () => {
' let $dd_rv0;',
' if ($dd_p0) $dd_entry($dd_p0, this, $dd_e0());',
' if (x > 0) {',
' return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0()) : $dd_rv0);',
' return ($dd_rv0 = 1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);',
' } else {',
' return ($dd_rv0 = -1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0(), $dd_e0()) : $dd_rv0);',
' return ($dd_rv0 = -1, $dd_p0 ? $dd_return($dd_p0, $dd_rv0, this, $dd_e0()) : $dd_rv0);',
' }',
'',
' } catch(e) { if ($dd_p0) $dd_throw($dd_p0, e, this, $dd_e0()); throw e; }',
Expand Down
31 changes: 20 additions & 11 deletions packages/plugins/live-debugger/src/transform/index.ts
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -282,7 +282,7 @@ export function transformCode(options: TransformOptions): TransformResult {
const idx = probeVarCounter++;
const probeVarName = `$dd_p${idx}`;
const entryVars = getVariableNames(node, true, false, babelTypes);
const exitVars = getVariableNames(node, true, true, babelTypes);
const exitVars = getVariableNames(node, false, true, babelTypes);

const isExpressionBody =
babelTypes.isArrowFunctionExpression(node) &&
Expand Down Expand Up @@ -399,16 +399,25 @@ function injectInstrumentation(s: MagicStringType, code: string, target: Functio
const entryVarsList = entryVars.join(', ');
const exitVarsList = exitVars.join(', ');

const shared = entryVarsList === exitVarsList;
const snapshotHelper = shared ? entryHelper : exitHelper;
const hasParams = entryVarsList !== '';
const hasLocals = exitVarsList !== '';

const argsArg = hasParams ? `, ${entryHelper}()` : '';
const returnArgsAndLocals = hasParams
? hasLocals
? `, ${entryHelper}(), ${exitHelper}()`
: `, ${entryHelper}()`
: hasLocals
? `, undefined, ${exitHelper}()`
: '';

// TODO: functionId is not escaped — if it contains a single quote (e.g. quoted method names),
// the generated code will be invalid. Escaping is not currently supported.
const probeDecl = `const ${probeVarName} = $dd_probes('${functionId}');`;
const entryHelperDecl = `const ${entryHelper} = () => ({${entryVarsList}});`;
const exitHelperDecl = shared ? '' : `const ${exitHelper} = () => ({${exitVarsList}});`;
const entryCall = `if (${probeVarName}) $dd_entry(${probeVarName}, this, ${entryHelper}());`;
const catchBlock = `catch(e) { if (${probeVarName}) $dd_throw(${probeVarName}, e, this, ${entryHelper}()); throw e; }`;
const entryHelperDecl = hasParams ? `const ${entryHelper} = () => ({${entryVarsList}});` : '';
const exitHelperDecl = hasLocals ? `const ${exitHelper} = () => ({${exitVarsList}});` : '';
const entryCall = `if (${probeVarName}) $dd_entry(${probeVarName}, this${argsArg});`;
const catchBlock = `catch(e) { if (${probeVarName}) $dd_throw(${probeVarName}, e, this${argsArg}); throw e; }`;

if (isExpressionBody) {
// Arrow expression body: (a) => expr
Expand Down Expand Up @@ -447,7 +456,7 @@ function injectInstrumentation(s: MagicStringType, code: string, target: Functio

const suffix = [
';',
`if (${probeVarName}) $dd_return(${probeVarName}, ${rvVarName}, this, ${entryHelper}(), ${snapshotHelper}());`,
`if (${probeVarName}) $dd_return(${probeVarName}, ${rvVarName}, this${returnArgsAndLocals});`,
`return ${rvVarName};`,
`} ${catchBlock}`,
'}',
Expand All @@ -472,7 +481,7 @@ function injectInstrumentation(s: MagicStringType, code: string, target: Functio
const postambleParts = [''];
if (target.needsTrailingReturn) {
postambleParts.push(
`if (${probeVarName}) $dd_return(${probeVarName}, undefined, this, ${entryHelper}(), ${snapshotHelper}());`,
`if (${probeVarName}) $dd_return(${probeVarName}, undefined, this${returnArgsAndLocals});`,
);
}
postambleParts.push(`} ${catchBlock}`, '');
Expand All @@ -490,13 +499,13 @@ function injectInstrumentation(s: MagicStringType, code: string, target: Functio
s.appendLeft(ret.argStart, `(${rvVarName} = `);
s.appendLeft(
ret.argEnd,
`, ${probeVarName} ? $dd_return(${probeVarName}, ${rvVarName}, this, ${entryHelper}(), ${snapshotHelper}()) : ${rvVarName})`,
`, ${probeVarName} ? $dd_return(${probeVarName}, ${rvVarName}, this${returnArgsAndLocals}) : ${rvVarName})`,
);
} else {
// return; → if (probe) $dd_return(...); return;
s.appendLeft(
ret.start,
`if (${probeVarName}) $dd_return(${probeVarName}, undefined, this, ${entryHelper}(), ${snapshotHelper}()); `,
`if (${probeVarName}) $dd_return(${probeVarName}, undefined, this${returnArgsAndLocals}); `,
);
}
}
Expand Down
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