Sourcemap types

src/Chunk.ts

@@ -14,7 +14,13 @@ import ExternalModule from './ExternalModule';
 import finalisers from './finalisers/index';
 import Graph from './Graph';
 import Module from './Module';
-import { GlobalsOption, OutputOptions, RawSourceMap, RenderedChunk, RenderedModule } from './rollup/types';
+import {
+	DecodedSourceMapOrMissing,
+	GlobalsOption,
+	OutputOptions,
+	RenderedChunk,
+	RenderedModule
+} from './rollup/types';
 import { Addons } from './utils/addons';
 import { toBase64 } from './utils/base64';
 import collapseSourcemaps from './utils/collapseSourcemaps';
@@ -676,7 +682,7 @@ export default class Chunk {
 		timeEnd('render format', 3);
 
 		let map: SourceMap = null as any;
-		const chunkSourcemapChain: RawSourceMap[] = [];
+		const chunkSourcemapChain: DecodedSourceMapOrMissing[] = [];
 
 		return renderChunk({
 			chunk: this,

src/Module.ts

@@ -32,9 +32,10 @@ import ExternalModule from './ExternalModule';
 import Graph from './Graph';
 import {
 	Asset,
+	DecodedSourceMapOrMissing,
 	EmittedChunk,
+	ExistingDecodedSourceMap,
 	ModuleJSON,
-	RawSourceMap,
 	ResolvedIdMap,
 	RollupError,
 	RollupWarning,
@@ -199,11 +200,11 @@ export default class Module {
 	manualChunkAlias: string = null as any;
 	moduleSideEffects: boolean;
 	originalCode!: string;
-	originalSourcemap!: RawSourceMap | null;
+	originalSourcemap!: ExistingDecodedSourceMap | null;
 	reexports: { [name: string]: ReexportDescription } = Object.create(null);
 	resolvedIds!: ResolvedIdMap;
 	scope!: ModuleScope;
-	sourcemapChain!: RawSourceMap[];
+	sourcemapChain!: DecodedSourceMapOrMissing[];
 	sources: string[] = [];
 	transformAssets?: Asset[];
 	transformChunks?: EmittedChunk[];
@@ -540,7 +541,7 @@ export default class Module {
 		this.code = code;
 		this.originalCode = originalCode;
 		this.originalSourcemap = originalSourcemap;
-		this.sourcemapChain = sourcemapChain as RawSourceMap[];
+		this.sourcemapChain = sourcemapChain;
 		if (transformAssets) {
 			this.transformAssets = transformAssets;
 		}

src/rollup/types.d.ts

@@ -38,6 +38,21 @@ export interface RollupLogProps {
 	url?: string;
 }
 
+export type SourceMapSegment =
+	| [number]
+	| [number, number, number, number]
+	| [number, number, number, number, number];
+
+export interface ExistingDecodedSourceMap {
+	file?: string;
+	mappings: SourceMapSegment[][];
+	names: string[];
+	sourceRoot?: string;
+	sources: string[];
+	sourcesContent?: string[];
+	version: number;
+}
+
 export interface ExistingRawSourceMap {
 	file?: string;
 	mappings: string;
@@ -48,7 +63,13 @@ export interface ExistingRawSourceMap {
 	version: number;
 }
 
-export type RawSourceMap = { mappings: '' } | ExistingRawSourceMap;
+export type DecodedSourceMapOrMissing =
+	| {
+			mappings?: never;
+			missing: true;
+			plugin: string;
+	  }
+	| ExistingDecodedSourceMap;
 
 export interface SourceMap {
 	file: string;
@@ -61,10 +82,12 @@ export interface SourceMap {
 	toUrl(): string;
 }
 
+export type SourceMapInput = ExistingRawSourceMap | string | null | { mappings: '' };
+
 export interface SourceDescription {
 	ast?: ESTree.Program;
 	code: string;
-	map?: string | RawSourceMap;
+	map?: SourceMapInput;
 	moduleSideEffects?: boolean | null;
 }
 
@@ -79,9 +102,9 @@ export interface TransformModuleJSON {
 	customTransformCache: boolean;
 	moduleSideEffects: boolean | null;
 	originalCode: string;
-	originalSourcemap: RawSourceMap | null;
+	originalSourcemap: ExistingDecodedSourceMap | null;
 	resolvedIds?: ResolvedIdMap;
-	sourcemapChain: (RawSourceMap | { missing: true; plugin: string })[];
+	sourcemapChain: DecodedSourceMapOrMissing[];
 	transformDependencies: string[] | null;
 }
 
@@ -207,8 +230,8 @@ export type TransformChunkHook = (
 	code: string,
 	options: OutputOptions
 ) =>
-	| Promise<{ code: string; map: RawSourceMap } | null | undefined>
-	| { code: string; map: RawSourceMap }
+	| Promise<{ code: string; map?: SourceMapInput } | null | undefined>
+	| { code: string; map?: SourceMapInput }
 	| null
 	| undefined;
 
@@ -218,8 +241,8 @@ export type RenderChunkHook = (
 	chunk: RenderedChunk,
 	options: OutputOptions
 ) =>
-	| Promise<{ code: string; map: RawSourceMap } | null>
-	| { code: string; map: RawSourceMap }
+	| Promise<{ code: string; map?: SourceMapInput } | null>
+	| { code: string; map?: SourceMapInput }
 	| string
 	| null;
 

src/utils/collapseSourcemaps.ts

@@ -1,7 +1,11 @@
 import { DecodedSourceMap, SourceMap } from 'magic-string';
 import Chunk from '../Chunk';
 import Module from '../Module';
-import { ExistingRawSourceMap, RawSourceMap } from '../rollup/types';
+import {
+	DecodedSourceMapOrMissing,
+	ExistingDecodedSourceMap,
+	SourceMapSegment
+} from '../rollup/types';
 import { error } from './error';
 import { basename, dirname, relative, resolve } from './path';
 
@@ -21,10 +25,6 @@ class Source {
 	}
 }
 
-type SourceMapSegmentVector =
-	| [number, number, number, number, number]
-	| [number, number, number, number];
-
 interface SourceMapSegmentObject {
 	column: number;
 	line: number;
@@ -33,11 +33,14 @@ interface SourceMapSegmentObject {
 }
 
 class Link {
-	mappings: SourceMapSegmentVector[][];
+	mappings: SourceMapSegment[][];
 	names: string[];
-	sources: Source[];
+	sources: (Source | Link)[];
 
-	constructor(map: { mappings: SourceMapSegmentVector[][]; names: string[] }, sources: Source[]) {
+	constructor(
+		map: { mappings: SourceMapSegment[][]; names: string[] },
+		sources: (Source | Link)[]
+	) {
 		this.sources = sources;
 		this.names = map.names;
 		this.mappings = map.mappings;
@@ -51,16 +54,17 @@ class Link {
 		const mappings = [];
 
 		for (const line of this.mappings) {
-			const tracedLine: SourceMapSegmentVector[] = [];
+			const tracedLine: SourceMapSegment[] = [];
 
 			for (const segment of line) {
+				if (segment.length == 1) continue;
 				const source = this.sources[segment[1]];
 				if (!source) continue;
 
 				const traced = source.traceSegment(
 					segment[2],
 					segment[3],
-					this.names[segment[4] as number]
+					segment.length === 5 ? this.names[segment[4]] : ''
 				);
 
 				if (traced) {
@@ -77,13 +81,11 @@ class Link {
 						sourcesContent[sourceIndex] !== traced.source.content
 					) {
 						error({
-							message: `Multiple conflicting contents for sourcemap source ${
-								traced.source.filename
-							}`
+							message: `Multiple conflicting contents for sourcemap source ${traced.source.filename}`
 						});
 					}
 
-					const tracedSegment: SourceMapSegmentVector = [
+					const tracedSegment: SourceMapSegment = [
 						segment[0],
 						sourceIndex,
 						traced.line,
@@ -97,7 +99,7 @@ class Link {
 							names.push(traced.name);
 						}
 
-						(tracedSegment as SourceMapSegmentVector)[4] = nameIndex;
+						(tracedSegment as SourceMapSegment)[4] = nameIndex;
 					}
 
 					tracedLine.push(tracedSegment);
@@ -110,7 +112,7 @@ class Link {
 		return { sources, sourcesContent, names, mappings };
 	}
 
-	traceSegment(line: number, column: number, name: string) {
+	traceSegment(line: number, column: number, name: string): SourceMapSegmentObject | null {
 		const segments = this.mappings[line];
 		if (!segments) return null;
 
@@ -122,13 +124,14 @@ class Link {
 			const m = (i + j) >> 1;
 			const segment = segments[m];
 			if (segment[0] === column) {
+				if (segment.length == 1) return null;
 				const source = this.sources[segment[1]];
 				if (!source) return null;
 
 				return source.traceSegment(
 					segment[2],
 					segment[3],
-					this.names[segment[4] as number] || name
+					segment.length === 5 ? this.names[segment[4]] : name
 				);
 			}
 			if (segment[0] > column) {
@@ -142,72 +145,69 @@ class Link {
 	}
 }
 
-// TODO TypeScript: Fix <any> typecasts
 export default function collapseSourcemaps(
 	bundle: Chunk,
 	file: string,
 	map: DecodedSourceMap,
 	modules: Module[],
-	bundleSourcemapChain: RawSourceMap[],
+	bundleSourcemapChain: DecodedSourceMapOrMissing[],
 	excludeContent: boolean
 ) {
-	function linkMap(source: Source, map: any) {
-		if (map.missing) {
-			bundle.graph.warn({
-				code: 'SOURCEMAP_BROKEN',
-				message: `Sourcemap is likely to be incorrect: a plugin${
-					map.plugin ? ` ('${map.plugin}')` : ``
-				} was used to transform files, but didn't generate a sourcemap for the transformation. Consult the plugin documentation for help`,
-				plugin: map.plugin,
-				url: `https://rollupjs.org/guide/en/#warning-sourcemap-is-likely-to-be-incorrect`
-			});
-
-			map = {
-				mappings: '',
-				names: []
-			};
+	function linkMap(source: Source | Link, map: DecodedSourceMapOrMissing) {
+		if (map.mappings) {
+			return new Link(map, [source]);
 		}
 
-		return new Link(map, [source]);
+		bundle.graph.warn({
+			code: 'SOURCEMAP_BROKEN',
+			message: `Sourcemap is likely to be incorrect: a plugin${
+				map.plugin ? ` ('${map.plugin}')` : ``
+			} was used to transform files, but didn't generate a sourcemap for the transformation. Consult the plugin documentation for help`,
+			plugin: map.plugin,
+			url: `https://rollupjs.org/guide/en/#warning-sourcemap-is-likely-to-be-incorrect`
+		});
+
+		return new Link(
+			{
+				mappings: [],
+				names: []
+			},
+			[source]
+		);
 	}
 
 	const moduleSources = modules
 		.filter(module => !module.excludeFromSourcemap)
 		.map(module => {
-			let sourcemapChain = module.sourcemapChain;
-
-			let source: Source;
-			const originalSourcemap = module.originalSourcemap as ExistingRawSourceMap;
+			let source: Source | Link;
+			const originalSourcemap = module.originalSourcemap;
 			if (!originalSourcemap) {
 				source = new Source(module.id, module.originalCode);
 			} else {
 				const sources = originalSourcemap.sources;
 				const sourcesContent = originalSourcemap.sourcesContent || [];
 
-				if (sources == null || (sources.length <= 1 && sources[0] == null)) {
-					source = new Source(module.id, sourcesContent[0]);
-					sourcemapChain = [originalSourcemap as RawSourceMap].concat(sourcemapChain);
-				} else {
-					// TODO indiscriminately treating IDs and sources as normal paths is probably bad.
-					const directory = dirname(module.id) || '.';
-					const sourceRoot = originalSourcemap.sourceRoot || '.';
+				// TODO indiscriminately treating IDs and sources as normal paths is probably bad.
+				const directory = dirname(module.id) || '.';
+				const sourceRoot = originalSourcemap.sourceRoot || '.';
 
-					const baseSources = sources.map(
-						(source, i) => new Source(resolve(directory, sourceRoot, source), sourcesContent[i])
-					);
+				const baseSources = sources.map(
+					(source, i) => new Source(resolve(directory, sourceRoot, source), sourcesContent[i])
+				);
 
-					source = new Link(originalSourcemap as any, baseSources) as any;
-				}
+				source = new Link(originalSourcemap, baseSources);
 			}
 
-			source = sourcemapChain.reduce(linkMap as any, source);
+			source = module.sourcemapChain.reduce(linkMap, source);
 
 			return source;
 		});
 
-	let source = new Link(map as any, moduleSources);
+	// DecodedSourceMap (from magic-string) uses a number[] instead of the more
+	// correct SourceMapSegment tuples. Cast it here to gain type safety.
+	let source = new Link(map as ExistingDecodedSourceMap, moduleSources);
 
-	source = bundleSourcemapChain.reduce(linkMap as any, source);
+	source = bundleSourcemapChain.reduce(linkMap, source);
 
 	let { sources, sourcesContent, names, mappings } = source.traceMappings();
 

src/utils/decodedSourcemap.ts

@@ -0,0 +1,29 @@
+import { decode } from 'sourcemap-codec';
+import { ExistingDecodedSourceMap, ExistingRawSourceMap, SourceMapInput } from '../rollup/types';
+
+type Input = SourceMapInput | ExistingDecodedSourceMap | undefined;
+
+export function decodedSourcemap(map: Input): ExistingDecodedSourceMap | null {
+	if (!map) return null;
+
+	if (typeof map === 'string') {
+		map = JSON.parse(map) as ExistingRawSourceMap;
+	}
+	if (map.mappings === '') {
+		return {
+			mappings: [],
+			names: [],
+			sources: [],
+			version: 3
+		};
+	}
+
+	let mappings;
+	if (typeof map.mappings === 'string') {
+		mappings = decode(map.mappings);
+	} else {
+		mappings = map.mappings;
+	}
+
+	return { ...(map as ExistingRawSourceMap | ExistingDecodedSourceMap), mappings };
+}