Improve support of non-relative imports in projects with a baseUrl

src/bundle-generator.ts

@@ -1,5 +1,6 @@
 import * as ts from 'typescript';
 import * as path from 'path';
+import * as fs from 'fs';
 
 import { compileDts } from './compile-dts';
 import { TypesUsageEvaluator } from './types-usage-evaluator';
@@ -138,7 +139,9 @@ export function generateDtsBundle(entries: readonly EntryPointConfig[], options:
 	const { program, rootFilesRemapping } = compileDts(entries.map((entry: EntryPointConfig) => entry.filePath), options.preferredConfigPath, options.followSymlinks);
 	const typeChecker = program.getTypeChecker();
 
-	const typeRoots = ts.getEffectiveTypeRoots(program.getCompilerOptions(), {});
+	const compilerOptions = program.getCompilerOptions();
+	const typeRoots = ts.getEffectiveTypeRoots(compilerOptions, {});
+	const baseUrl = compilerOptions.baseUrl;
 
 	const sourceFiles = program.getSourceFiles().filter((file: ts.SourceFile) => {
 		return !program.isSourceFileDefaultLibrary(file);
@@ -357,7 +360,7 @@ export function generateDtsBundle(entries: readonly EntryPointConfig[], options:
 					}
 
 					// we don't need to specify exact file here since we need to figure out whether a file is external or internal one
-					const moduleFileName = resolveModuleFileName(rootSourceFile.fileName, node.argument.literal.text);
+					const moduleFileName = resolveModuleFileName(rootSourceFile.fileName, node.argument.literal.text, baseUrl);
 					return !getModuleInfo(moduleFileName, criteria).isExternal;
 				},
 			},
@@ -582,8 +585,21 @@ function updateResultForModuleDeclaration(moduleDecl: ts.ModuleDeclaration, para
 	);
 }
 
-function resolveModuleFileName(currentFileName: string, moduleName: string): string {
-	return moduleName.startsWith('.') ? fixPath(path.join(currentFileName, '..', moduleName)) : `node_modules/${moduleName}/`;
+function resolveModuleFileName(currentFileName: string, moduleName: string, baseUrl?: string): string {
+	if (moduleName.startsWith('.')) {
+		return fixPath(path.join(currentFileName, '..', moduleName));
+	}
+
+	// determine if the module is a non-relative import that can be resolved with the baseUrl
+	if (baseUrl !== undefined) {
+		const filePath = `${path.join(baseUrl, moduleName)}.ts`;
+
+		if (fs.existsSync(filePath)) {
+			return fixPath(filePath);
+		}
+	}
+
+	return `node_modules/${moduleName}/`;
 }
 
 function addTypesReference(library: string, typesReferences: Set<string>): void {

tests/e2e/test-cases/import-from-non-relative-path-inferred-type/config.ts

@@ -0,0 +1,5 @@
+import { TestCaseConfig } from '../../test-cases/test-case-config';
+
+const config: TestCaseConfig = {};
+
+export = config;

tests/e2e/test-cases/import-from-non-relative-path-inferred-type/input.ts

@@ -0,0 +1,5 @@
+import { returnMyType } from "field/type";
+
+export function test() {
+    return returnMyType()
+}

tests/e2e/test-cases/import-from-non-relative-path-inferred-type/output.d.ts

@@ -0,0 +1,6 @@
+export interface MyType {
+	field: string;
+}
+export declare function test(): MyType;
+
+export {};

tests/e2e/test-cases/import-from-non-relative-path-inferred-type/src/field/type.ts

@@ -0,0 +1,9 @@
+export interface MyType {
+	field: string;
+}
+
+export function returnMyType(): MyType {
+    return {
+        field: "test"
+    }
+}

tests/e2e/test-cases/import-from-non-relative-path-inferred-type/tsconfig.json

@@ -0,0 +1,6 @@
+{
+	"extends": "../tsconfig.json",
+	"compilerOptions": {
+		"baseUrl": "./src"
+	}
+}