fix #3169: print negative properties as computed

CHANGELOG.md

@@ -85,6 +85,27 @@
     let Foo = _Foo;
     ```
 
+* Fix a minification regression with negative numeric properties ([#3169](https://github.com/evanw/esbuild/issues/3169))
+
+    Version 0.18.0 introduced a regression where computed properties with negative numbers were incorrectly shortened into a non-computed property when minification was enabled. This regression has been fixed:
+
+    ```js
+    // Original code
+    x = {
+      [1]: 1,
+      [-1]: -1,
+      [NaN]: NaN,
+      [Infinity]: Infinity,
+      [-Infinity]: -Infinity,
+    }
+
+    // Old output (with --minify)
+    x={1:1,-1:-1,NaN:NaN,1/0:1/0,-1/0:-1/0};
+
+    // New output (with --minify)
+    x={1:1,[-1]:-1,NaN:NaN,[1/0]:1/0,[-1/0]:-1/0};
+    ```
+
 ## 0.18.3
 
 * Fix a panic due to empty static class blocks ([#3161](https://github.com/evanw/esbuild/issues/3161))

internal/js_printer/js_printer.go

@@ -1043,7 +1043,20 @@ func (p *printer) printProperty(property js_ast.Property) {
 		}
 	}
 
-	if property.Flags.Has(js_ast.PropertyIsComputed) {
+	isComputed := property.Flags.Has(js_ast.PropertyIsComputed)
+
+	// Automatically print numbers that would cause a syntax error as computed properties
+	if !isComputed {
+		if key, ok := property.Key.Data.(*js_ast.ENumber); ok {
+			if math.Signbit(key.Value) || (key.Value == positiveInfinity && p.options.MinifySyntax) {
+				// "{ -1: 0 }" must be printed as "{ [-1]: 0 }"
+				// "{ 1/0: 0 }" must be printed as "{ [1/0]: 0 }"
+				isComputed = true
+			}
+		}
+	}
+
+	if isComputed {
 		p.addSourceMapping(property.Loc)
 		isMultiLine := p.willPrintExprCommentsAtLoc(property.Key.Loc) || p.willPrintExprCommentsAtLoc(property.CloseBracketLoc)
 		p.print("[")

scripts/end-to-end-tests.js

@@ -2710,6 +2710,36 @@ for (const minify of [[], ['--minify-syntax']]) {
     test(['in.js', '--outfile=node.js'].concat(minify), {
       'in.js': `let fn = (a, b) => { if (a && (x = () => y) && b) return; var x; let y = 123; if (x() !== 123) throw 'fail' }; fn(fn)`,
     }),
+    test(['in.js', '--outfile=node.js'].concat(minify), {
+      'in.js': `
+        var x = { [-0]: 1 }; if (x['0'] !== 1 || x['-0'] !== void 0) throw 'fail: -0'
+        var x = { [-1]: 1 }; if (x['-1'] !== 1) throw 'fail: -1'
+        var x = { [NaN]: 1 }; if (x['NaN'] !== 1) throw 'fail: NaN'
+        var x = { [Infinity]: 1 }; if (x['Infinity'] !== 1) throw 'fail: Infinity'
+        var x = { [-Infinity]: 1 }; if (x['-Infinity'] !== 1) throw 'fail: -Infinity'
+        var x = { [1e5]: 1 }; if (x['100000'] !== 1) throw 'fail: 1e5'
+        var x = { [-1e5]: 1 }; if (x['-100000'] !== 1) throw 'fail: -1e5'
+        var x = { [1e100]: 1 }; if (x['1e+100'] !== 1) throw 'fail: 1e100'
+        var x = { [-1e100]: 1 }; if (x['-1e+100'] !== 1) throw 'fail: -1e100'
+        var x = { [0xFFFF_FFFF_FFFF]: 1 }; if (x['281474976710655'] !== 1) throw 'fail: 0xFFFF_FFFF_FFFF'
+        var x = { [-0xFFFF_FFFF_FFFF]: 1 }; if (x['-281474976710655'] !== 1) throw 'fail: -0xFFFF_FFFF_FFFF'
+      `,
+    }),
+    test(['in.js', '--outfile=node.js'].concat(minify), {
+      'in.js': `
+        var x = class { static [-0] = 1 }; if (x['0'] !== 1 || x['-0'] !== void 0) throw 'fail: -0'
+        var x = class { static [-1] = 1 }; if (x['-1'] !== 1) throw 'fail: -1'
+        var x = class { static [NaN] = 1 }; if (x['NaN'] !== 1) throw 'fail: NaN'
+        var x = class { static [Infinity] = 1 }; if (x['Infinity'] !== 1) throw 'fail: Infinity'
+        var x = class { static [-Infinity] = 1 }; if (x['-Infinity'] !== 1) throw 'fail: -Infinity'
+        var x = class { static [1e5] = 1 }; if (x['100000'] !== 1) throw 'fail: 1e5'
+        var x = class { static [-1e5] = 1 }; if (x['-100000'] !== 1) throw 'fail: -1e5'
+        var x = class { static [1e100] = 1 }; if (x['1e+100'] !== 1) throw 'fail: 1e100'
+        var x = class { static [-1e100] = 1 }; if (x['-1e+100'] !== 1) throw 'fail: -1e100'
+        var x = class { static [0xFFFF_FFFF_FFFF] = 1 }; if (x['281474976710655'] !== 1) throw 'fail: 0xFFFF_FFFF_FFFF'
+        var x = class { static [-0xFFFF_FFFF_FFFF] = 1 }; if (x['-281474976710655'] !== 1) throw 'fail: -0xFFFF_FFFF_FFFF'
+      `,
+    }),
   )
 
   // Check property access simplification