Handle case sensitivity correctly in source map decoder

Author: sheetalkamat

src/compiler/sourcemapDecoder.ts

@@ -57,6 +57,7 @@ namespace ts.sourcemaps {
         fileExists(path: string): boolean;
         getCanonicalFileName(path: string): string;
         log(text: string): void;
+        useCaseSensitiveFileNames: boolean;
     }
 
     export function decode(host: SourceMapDecodeHost, mapPath: string, map: SourceMapData, program?: Program, fallbackCache = createSourceFileLikeCache(host)): SourceMapper {
@@ -79,7 +80,7 @@ namespace ts.sourcemaps {
                 // if no exact match, closest is 2's compliment of result
                 targetIndex = ~targetIndex;
             }
-            if (!maps[targetIndex] || comparePaths(loc.fileName, maps[targetIndex].sourcePath, sourceRoot) !== 0) {
+            if (!maps[targetIndex] || comparePaths(loc.fileName, maps[targetIndex].sourcePath, sourceRoot, !host.useCaseSensitiveFileNames) !== 0) {
                 return loc;
             }
             return { fileName: toPath(map.file!, sourceRoot, host.getCanonicalFileName), position: maps[targetIndex].emittedPosition }; // Closest pos
@@ -129,7 +130,7 @@ namespace ts.sourcemaps {
         }
 
         function compareProcessedPositionSourcePositions(a: ProcessedSourceMapPosition, b: ProcessedSourceMapPosition) {
-            return comparePaths(a.sourcePath, b.sourcePath, sourceRoot) ||
+            return comparePaths(a.sourcePath, b.sourcePath, sourceRoot, !host.useCaseSensitiveFileNames) ||
                 compareValues(a.sourcePosition, b.sourcePosition);
         }
 

src/services/services.ts

@@ -1139,7 +1139,7 @@ namespace ts {
         const useCaseSensitiveFileNames = hostUsesCaseSensitiveFileNames(host);
         const getCanonicalFileName = createGetCanonicalFileName(useCaseSensitiveFileNames);
 
-        const sourceMapper = getSourceMapper(getCanonicalFileName, currentDirectory, log, host, () => program);
+        const sourceMapper = getSourceMapper(useCaseSensitiveFileNames, currentDirectory, log, host, () => program);
 
         function getValidSourceFile(fileName: string): SourceFile {
             const sourceFile = program.getSourceFile(fileName);

src/services/sourcemaps.ts

@@ -13,12 +13,13 @@ namespace ts {
     }
 
     export function getSourceMapper(
-        getCanonicalFileName: GetCanonicalFileName,
+        useCaseSensitiveFileNames: boolean,
         currentDirectory: string,
         log: (message: string) => void,
         host: LanguageServiceHost,
         getProgram: () => Program,
     ): SourceMapper {
+        const getCanonicalFileName = createGetCanonicalFileName(useCaseSensitiveFileNames);
         let sourcemappedFileCache: SourceFileLikeCache;
         return { tryGetOriginalLocation, tryGetGeneratedLocation, toLineColumnOffset, clearCache };
 
@@ -56,6 +57,7 @@ namespace ts {
             return file.sourceMapper = sourcemaps.decode({
                 readFile: s => host.readFile!(s), // TODO: GH#18217
                 fileExists: s => host.fileExists!(s), // TODO: GH#18217
+                useCaseSensitiveFileNames,
                 getCanonicalFileName,
                 log,
             }, mapFileName, maps, getProgram(), sourcemappedFileCache);
@@ -105,7 +107,11 @@ namespace ts {
 
         function tryGetGeneratedLocation(info: sourcemaps.SourceMappableLocation): sourcemaps.SourceMappableLocation | undefined {
             const program = getProgram();
-            const declarationPath = getDeclarationEmitOutputFilePathWorker(info.fileName, program.getCompilerOptions(), currentDirectory, program.getCommonSourceDirectory(), getCanonicalFileName);
+            const options = program.getCompilerOptions();
+            const outPath = options.outFile || options.out;
+            const declarationPath = outPath ?
+                removeFileExtension(outPath) + Extension.Dts :
+                getDeclarationEmitOutputFilePathWorker(info.fileName, program.getCompilerOptions(), currentDirectory, program.getCommonSourceDirectory(), getCanonicalFileName);
             if (declarationPath === undefined) return undefined;
             const declarationFile = getFile(declarationPath);
             if (!declarationFile) return undefined;