fix: improve source code location metadata accuracy by accounting for preprocessor sourcemap and one based counting

package-lock.json

@@ -11,6 +11,7 @@
       "devDependencies": {
         "@ampproject/remapping": "^0.3.0",
         "@jridgewell/sourcemap-codec": "^1.4.14",
+        "@jridgewell/trace-mapping": "^0.3.17",
         "@rollup/plugin-commonjs": "^11.0.0",
         "@rollup/plugin-json": "^6.0.0",
         "@rollup/plugin-node-resolve": "^11.2.1",
@@ -168,6 +169,25 @@
       "integrity": "sha512-XPSJHWmi394fuUuzDnGz1wiKqWfo1yXecHQMRf2l6hztTO+nPru658AyDngaBe7isIxEkRsPR3FZh+s7iVa4Uw==",
       "dev": true
     },
+    "node_modules/@jridgewell/trace-mapping": {
+      "version": "0.3.17",
+      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.17.tgz",
+      "integrity": "sha512-MCNzAp77qzKca9+W/+I0+sEpaUnZoeasnghNeVc41VZCEKaCH73Vq3BZZ/SzWIgrqE4H4ceI+p+b6C0mHf9T4g==",
+      "dev": true,
+      "dependencies": {
+        "@jridgewell/resolve-uri": "3.1.0",
+        "@jridgewell/sourcemap-codec": "1.4.14"
+      }
+    },
+    "node_modules/@jridgewell/trace-mapping/node_modules/@jridgewell/resolve-uri": {
+      "version": "3.1.0",
+      "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.0.tgz",
+      "integrity": "sha512-F2msla3tad+Mfht5cJq7LSXcdudKTWCVYUgw6pLFOOHSTtZlj6SWNYAp+AhuqLmWdBO2X5hPrLcu8cVP8fy28w==",
+      "dev": true,
+      "engines": {
+        "node": ">=6.0.0"
+      }
+    },
     "node_modules/@nodelib/fs.scandir": {
       "version": "2.1.5",
       "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",
@@ -5485,6 +5505,24 @@
       "integrity": "sha512-XPSJHWmi394fuUuzDnGz1wiKqWfo1yXecHQMRf2l6hztTO+nPru658AyDngaBe7isIxEkRsPR3FZh+s7iVa4Uw==",
       "dev": true
     },
+    "@jridgewell/trace-mapping": {
+      "version": "0.3.17",
+      "resolved": "https://registry.npmjs.org/@jridgewell/trace-mapping/-/trace-mapping-0.3.17.tgz",
+      "integrity": "sha512-MCNzAp77qzKca9+W/+I0+sEpaUnZoeasnghNeVc41VZCEKaCH73Vq3BZZ/SzWIgrqE4H4ceI+p+b6C0mHf9T4g==",
+      "dev": true,
+      "requires": {
+        "@jridgewell/resolve-uri": "3.1.0",
+        "@jridgewell/sourcemap-codec": "1.4.14"
+      },
+      "dependencies": {
+        "@jridgewell/resolve-uri": {
+          "version": "3.1.0",
+          "resolved": "https://registry.npmjs.org/@jridgewell/resolve-uri/-/resolve-uri-3.1.0.tgz",
+          "integrity": "sha512-F2msla3tad+Mfht5cJq7LSXcdudKTWCVYUgw6pLFOOHSTtZlj6SWNYAp+AhuqLmWdBO2X5hPrLcu8cVP8fy28w==",
+          "dev": true
+        }
+      }
+    },
     "@nodelib/fs.scandir": {
       "version": "2.1.5",
       "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",

package.json

@@ -121,6 +121,7 @@
   "devDependencies": {
     "@ampproject/remapping": "^0.3.0",
     "@jridgewell/sourcemap-codec": "^1.4.14",
+    "@jridgewell/trace-mapping": "^0.3.17",
     "@rollup/plugin-commonjs": "^11.0.0",
     "@rollup/plugin-json": "^6.0.0",
     "@rollup/plugin-node-resolve": "^11.2.1",

src/compiler/compile/Component.ts

@@ -1,3 +1,4 @@
+import { TraceMap, originalPositionFor } from '@jridgewell/trace-mapping';
 import { walk } from 'estree-walker';
 import { getLocator } from 'locate-character';
 import Stats from '../Stats';
@@ -143,8 +144,16 @@ export default class Component {
 					.replace(process.cwd(), '')
 					.replace(regex_leading_directory_separator, '')
 				: compile_options.filename);
-		this.locate = getLocator(this.source, { offsetLine: 1 });
-
+		const locator = getLocator(this.source, { offsetLine: 1 });
+		const tracer = compile_options.sourcemap ? new TraceMap(compile_options.sourcemap) : undefined;
+		this.locate = (c) => {
+			let location:{line:number,column:number} = locator(c);
+			if (tracer) {
+				location = originalPositionFor(tracer, location);
+			}
+			location.line += 1; // make line one based
+			return location;
+		};
 		// styles
 		this.stylesheet = new Stylesheet({
 			source,

test/runtime/samples/element-source-location/_config.js

@@ -11,14 +11,14 @@ export default {
 
 		assert.deepEqual(h1.__svelte_meta.loc, {
 			file: path.relative(process.cwd(), path.resolve(__dirname, 'main.svelte')),
-			line: 4,
+			line: 5,
 			column: 0,
 			char: 53
 		});
 
 		assert.deepEqual(p.__svelte_meta.loc, {
 			file: path.relative(process.cwd(), path.resolve(__dirname, 'Foo.svelte')),
-			line: 1,
+			line: 2,
 			column: 1,
 			char: 7
 		});