Reimplement rootDirs (#1540)

Author: jakebailey

internal/module/resolver.go

@@ -1081,7 +1081,16 @@ func (r *resolutionState) getOriginalAndResolvedFileName(fileName string) (strin
 }
 
 func (r *resolutionState) tryLoadModuleUsingOptionalResolutionSettings() *resolved {
-	return r.tryLoadModuleUsingPathsIfEligible()
+	if resolved := r.tryLoadModuleUsingPathsIfEligible(); !resolved.shouldContinueSearching() {
+		return resolved
+	}
+
+	if !tspath.IsExternalModuleNameRelative(r.name) {
+		// No more tryLoadModuleUsingBaseUrl.
+		return continueSearching()
+	} else {
+		return r.tryLoadModuleUsingRootDirs()
+	}
 }
 
 func (r *resolutionState) tryLoadModuleUsingPathsIfEligible() *resolved {
@@ -1136,6 +1145,82 @@ func (r *resolutionState) tryLoadModuleUsingPaths(extensions extensions, moduleN
 	return continueSearching()
 }
 
+func (r *resolutionState) tryLoadModuleUsingRootDirs() *resolved {
+	if len(r.compilerOptions.RootDirs) == 0 {
+		return continueSearching()
+	}
+
+	if r.resolver.traceEnabled() {
+		r.resolver.host.Trace(diagnostics.X_rootDirs_option_is_set_using_it_to_resolve_relative_module_name_0.Format(r.name))
+	}
+
+	candidate := tspath.NormalizePath(tspath.CombinePaths(r.containingDirectory, r.name))
+
+	var matchedRootDir string
+	var matchedNormalizedPrefix string
+	for _, rootDir := range r.compilerOptions.RootDirs {
+		// rootDirs are expected to be absolute
+		// in case of tsconfig.json this will happen automatically - compiler will expand relative names
+		// using location of tsconfig.json as base location
+		normalizedRoot := tspath.NormalizePath(rootDir)
+		if !strings.HasSuffix(normalizedRoot, "/") {
+			normalizedRoot += "/"
+		}
+		isLongestMatchingPrefix := strings.HasPrefix(candidate, normalizedRoot) &&
+			(matchedNormalizedPrefix == "" || len(matchedNormalizedPrefix) < len(normalizedRoot))
+
+		if r.resolver.traceEnabled() {
+			r.resolver.host.Trace(diagnostics.Checking_if_0_is_the_longest_matching_prefix_for_1_2.Format(normalizedRoot, candidate, isLongestMatchingPrefix))
+		}
+
+		if isLongestMatchingPrefix {
+			matchedNormalizedPrefix = normalizedRoot
+			matchedRootDir = rootDir
+		}
+	}
+
+	if matchedNormalizedPrefix != "" {
+		if r.resolver.traceEnabled() {
+			r.resolver.host.Trace(diagnostics.Longest_matching_prefix_for_0_is_1.Format(candidate, matchedNormalizedPrefix))
+		}
+		suffix := candidate[len(matchedNormalizedPrefix):]
+
+		// first - try to load from a initial location
+		if r.resolver.traceEnabled() {
+			r.resolver.host.Trace(diagnostics.Loading_0_from_the_root_dir_1_candidate_location_2.Format(suffix, matchedNormalizedPrefix, candidate))
+		}
+		loader := func(extensions extensions, candidate string, onlyRecordFailures bool) *resolved {
+			return r.nodeLoadModuleByRelativeName(extensions, candidate, onlyRecordFailures, true /*considerPackageJson*/)
+		}
+		if resolvedFileName := loader(r.extensions, candidate, !r.resolver.host.FS().DirectoryExists(r.containingDirectory)); !resolvedFileName.shouldContinueSearching() {
+			return resolvedFileName
+		}
+
+		if r.resolver.traceEnabled() {
+			r.resolver.host.Trace(diagnostics.Trying_other_entries_in_rootDirs.Format())
+		}
+		// then try to resolve using remaining entries in rootDirs
+		for _, rootDir := range r.compilerOptions.RootDirs {
+			if rootDir == matchedRootDir {
+				// skip the initially matched entry
+				continue
+			}
+			candidate := tspath.CombinePaths(tspath.NormalizePath(rootDir), suffix)
+			if r.resolver.traceEnabled() {
+				r.resolver.host.Trace(diagnostics.Loading_0_from_the_root_dir_1_candidate_location_2.Format(suffix, rootDir, candidate))
+			}
+			baseDirectory := tspath.GetDirectoryPath(candidate)
+			if resolvedFileName := loader(r.extensions, candidate, !r.resolver.host.FS().DirectoryExists(baseDirectory)); !resolvedFileName.shouldContinueSearching() {
+				return resolvedFileName
+			}
+		}
+		if r.resolver.traceEnabled() {
+			r.resolver.host.Trace(diagnostics.Module_resolution_using_rootDirs_has_failed.Format())
+		}
+	}
+	return continueSearching()
+}
+
 func (r *resolutionState) nodeLoadModuleByRelativeName(extensions extensions, candidate string, onlyRecordFailures bool, considerPackageJson bool) *resolved {
 	if r.resolver.traceEnabled() {
 		r.resolver.host.Trace(diagnostics.Loading_module_as_file_Slash_folder_candidate_module_location_0_target_file_types_Colon_1.Format(candidate, extensions.String()))

internal/testrunner/compiler_runner.go

@@ -582,9 +582,6 @@ func (c *compilerTest) containsUnsupportedOptionsForDiagnostics() bool {
 	if c.options.BaseUrl != "" {
 		return true
 	}
-	if c.options.RootDirs != nil {
-		return true
-	}
 	if c.options.OutFile != "" {
 		return true
 	}

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.errors.txt

@@ -11,6 +11,12 @@ use(x.toFixed());
 export let x: number;
 
 
+//// [file3.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.x = void 0;
+const file2_1 = require("../file2");
+Object.defineProperty(exports, "x", { enumerable: true, get: function () { return file2_1.x; } });
 //// [file1.js]
 "use strict";
 Object.defineProperty(exports, "__esModule", { value: true });

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.js

@@ -1,15 +1,12 @@
 --- old.pathMappingBasedModuleResolution6_node.js
 +++ new.pathMappingBasedModuleResolution6_node.js
-@@= skipped -10, +10 lines =@@
- export let x: number;
-
-
--//// [file3.js]
--"use strict";
--Object.defineProperty(exports, "__esModule", { value: true });
--exports.x = void 0;
+@@= skipped -14, +14 lines =@@
+ "use strict";
+ Object.defineProperty(exports, "__esModule", { value: true });
+ exports.x = void 0;
 -var file2_1 = require("../file2");
--Object.defineProperty(exports, "x", { enumerable: true, get: function () { return file2_1.x; } });
++const file2_1 = require("../file2");
+ Object.defineProperty(exports, "x", { enumerable: true, get: function () { return file2_1.x; } });
  //// [file1.js]
  "use strict";
  Object.defineProperty(exports, "__esModule", { value: true });

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.js.diff

@@ -10,9 +10,15 @@ declare function use(x: string);
 
 use(x.toFixed());
 >use : Symbol(use, Decl(file1.ts, 0, 34))
+>x.toFixed : Symbol(toFixed, Decl(lib.es5.d.ts, --, --))
 >x : Symbol(x, Decl(file1.ts, 0, 8))
+>toFixed : Symbol(toFixed, Decl(lib.es5.d.ts, --, --))
 
 === c:/root/src/file2/index.d.ts ===
 export let x: number;
 >x : Symbol(x, Decl(index.d.ts, 0, 10))
 
+=== c:/root/generated/src/project/file3.ts ===
+export {x} from "../file2";
+>x : Symbol(x, Decl(file3.ts, 0, 8))
+

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.symbols

@@ -5,13 +5,10 @@
  use(x.toFixed());
  >use : Symbol(use, Decl(file1.ts, 0, 34))
 ->x.toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
++>x.toFixed : Symbol(toFixed, Decl(lib.es5.d.ts, --, --))
  >x : Symbol(x, Decl(file1.ts, 0, 8))
 ->toFixed : Symbol(Number.toFixed, Decl(lib.es5.d.ts, --, --))
++>toFixed : Symbol(toFixed, Decl(lib.es5.d.ts, --, --))
 
  === c:/root/src/file2/index.d.ts ===
- export let x: number;
- >x : Symbol(x, Decl(index.d.ts, 0, 10))
--
--=== c:/root/generated/src/project/file3.ts ===
--export {x} from "../file2";
-->x : Symbol(x, Decl(file3.ts, 0, 8))
+ export let x: number;

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.symbols.diff

@@ -2,7 +2,7 @@
 
 === c:/root/src/file1.ts ===
 import {x} from "./project/file3";
->x : any
+>x : number
 
 declare function use(x: string);
 >use : (x: string) => any
@@ -11,12 +11,16 @@ declare function use(x: string);
 use(x.toFixed());
 >use(x.toFixed()) : any
 >use : (x: string) => any
->x.toFixed() : any
->x.toFixed : any
->x : any
->toFixed : any
+>x.toFixed() : string
+>x.toFixed : (fractionDigits?: number) => string
+>x : number
+>toFixed : (fractionDigits?: number) => string
 
 === c:/root/src/file2/index.d.ts ===
 export let x: number;
 >x : number
 
+=== c:/root/generated/src/project/file3.ts ===
+export {x} from "../file2";
+>x : number
+

testdata/baselines/reference/submodule/compiler/pathMappingBasedModuleResolution6_node.types

@@ -1,4 +1,4 @@
-c:/root/src/file1.ts(1,17): error TS2307: Cannot find module './project/file2' or its corresponding type declarations.
+c:/root/generated/src/project/file2.ts(2,17): error TS2307: Cannot find module 'templates/module2' or its corresponding type declarations.
 c:/root/src/tsconfig.json(3,9): error TS5102: Option 'baseUrl' has been removed. Please remove it from your configuration.
   Use '"paths": {"*": ["./../*"]}' instead.
 c:/root/src/tsconfig.json(6,17): error TS5090: Non-relative paths are not allowed. Did you forget a leading './'?
@@ -32,10 +32,8 @@ c:/root/src/tsconfig.json(10,17): error TS5090: Non-relative paths are not allow
         }
     }
 
-==== c:/root/src/file1.ts (1 errors) ====
+==== c:/root/src/file1.ts (0 errors) ====
     import {x} from "./project/file2";
-                    ~~~~~~~~~~~~~~~~~
-!!! error TS2307: Cannot find module './project/file2' or its corresponding type declarations.
     import {y} from "module3";
 
     declare function use(x: string);
@@ -45,9 +43,11 @@ c:/root/src/tsconfig.json(10,17): error TS5090: Non-relative paths are not allow
 ==== c:/root/src/file3/index.d.ts (0 errors) ====
     export let x: number;
 
-==== c:/root/generated/src/project/file2.ts (0 errors) ====
+==== c:/root/generated/src/project/file2.ts (1 errors) ====
     import {a} from "module1";
     import {b} from "templates/module2";
+                    ~~~~~~~~~~~~~~~~~~~
+!!! error TS2307: Cannot find module 'templates/module2' or its corresponding type declarations.
     import {x as c} from "../file3";
     export let x = a + b + c;