fix #3985: entryPoint metadata for copy loader

CHANGELOG.md

@@ -64,6 +64,10 @@
 
     This can sometimes expose additional minification opportunities.
 
+* Include `entryPoint` metadata for the `copy` loader ([#3985](https://github.com/evanw/esbuild/issues/3985))
+
+    Almost all entry points already include a `entryPoint` field in the `outputs` map in esbuild's build metadata. However, this wasn't the case for the `copy` loader as that loader is a special-case that doesn't behave like other loaders. This release adds the `entryPoint` field in this case.
+
 * Avoid using the parent directory name for determinism ([#3998](https://github.com/evanw/esbuild/issues/3998))
 
     To make generated code more readable, esbuild includes the name of the source file when generating certain variable names within the file. Specifically bundling a CommonJS file generates a variable to store the lazily-evaluated module initializer. However, if a file is named `index.js` (or with a different extension), esbuild will use the name of the parent directory instead for a better name (since many packages have files all named `index.js` but have unique directory names).

internal/bundler/bundler.go

@@ -2577,11 +2577,13 @@ func (s *scanner) processScannedFiles(entryPointMeta []graph.EntryPoint) []scann
 			// the entry point itself.
 			customFilePath := ""
 			useOutputFile := false
+			isEntryPoint := false
 			if result.file.inputFile.Loader == config.LoaderCopy {
 				if metaIndex, ok := entryPointSourceIndexToMetaIndex[uint32(sourceIndex)]; ok {
 					template = s.options.EntryPathTemplate
 					customFilePath = entryPointMeta[metaIndex].OutputPath
 					useOutputFile = s.options.AbsOutputFile != ""
+					isEntryPoint = true
 				}
 			}
 
@@ -2632,8 +2634,14 @@ func (s *scanner) processScannedFiles(entryPointMeta []graph.EntryPoint) []scann
 					helpers.QuoteForJSON(result.file.inputFile.Source.PrettyPath, s.options.ASCIIOnly),
 					len(bytes),
 				)
+				entryPointJSON := ""
+				if isEntryPoint {
+					entryPointJSON = fmt.Sprintf("\"entryPoint\": %s,\n      ",
+						helpers.QuoteForJSON(result.file.inputFile.Source.PrettyPath, s.options.ASCIIOnly))
+				}
 				jsonMetadataChunk = fmt.Sprintf(
-					"{\n      \"imports\": [],\n      \"exports\": [],\n      \"inputs\": %s,\n      \"bytes\": %d\n    }",
+					"{\n      \"imports\": [],\n      \"exports\": [],\n      %s\"inputs\": %s,\n      \"bytes\": %d\n    }",
+					entryPointJSON,
 					inputs,
 					len(bytes),
 				)

internal/bundler_tests/bundler_loader_test.go

@@ -1194,6 +1194,7 @@ func TestLoaderCopyWithBundleEntryPoint(t *testing.T) {
 				".css":  config.LoaderCSS,
 				".file": config.LoaderCopy,
 			},
+			NeedsMetafile: true,
 		},
 	})
 }

internal/bundler_tests/snapshots/snapshots_loader.txt

@@ -337,6 +337,80 @@ console.log(x);
 body {
   background: url("../assets/some.file");
 }
+---------- metafile.json ----------
+{
+  "inputs": {
+    "Users/user/project/assets/some.file": {
+      "bytes": 5,
+      "imports": []
+    },
+    "Users/user/project/src/entry.js": {
+      "bytes": 63,
+      "imports": [
+        {
+          "path": "Users/user/project/assets/some.file",
+          "kind": "import-statement",
+          "original": "../assets/some.file"
+        }
+      ],
+      "format": "esm"
+    },
+    "Users/user/project/src/entry.css": {
+      "bytes": 64,
+      "imports": [
+        {
+          "path": "Users/user/project/assets/some.file",
+          "kind": "url-token",
+          "original": "../assets/some.file"
+        }
+      ]
+    }
+  },
+  "outputs": {
+    "out/assets/some.file": {
+      "imports": [],
+      "exports": [],
+      "entryPoint": "Users/user/project/assets/some.file",
+      "inputs": {
+        "Users/user/project/assets/some.file": {
+          "bytesInOutput": 5
+        }
+      },
+      "bytes": 5
+    },
+    "out/src/entry.js": {
+      "imports": [
+        {
+          "path": "out/assets/some.file",
+          "kind": "import-statement"
+        }
+      ],
+      "exports": [],
+      "entryPoint": "Users/user/project/src/entry.js",
+      "inputs": {
+        "Users/user/project/src/entry.js": {
+          "bytesInOutput": 53
+        }
+      },
+      "bytes": 88
+    },
+    "out/src/entry.css": {
+      "imports": [
+        {
+          "path": "out/assets/some.file",
+          "kind": "url-token"
+        }
+      ],
+      "entryPoint": "Users/user/project/src/entry.css",
+      "inputs": {
+        "Users/user/project/src/entry.css": {
+          "bytesInOutput": 51
+        }
+      },
+      "bytes": 90
+    }
+  }
+}
 
 ================================================================================
 TestLoaderCopyWithBundleFromCSS