Merge pull request #16126 from davidungar/exit-dont-crash-for-missing-output-file-map

Instead of crashing for bad output-file-map path, exit. Also print the path in the diagnostic.

Author: David Ungar

include/swift/AST/DiagnosticsDriver.def

@@ -61,7 +61,7 @@ ERROR(error_cannot_specify__o_for_multiple_outputs,none,
       "cannot specify -o when generating multiple output files", ())
 
 ERROR(error_unable_to_load_output_file_map, none,
-      "unable to load output file map: %0", (StringRef))
+      "unable to load output file map '%1': %0", (StringRef, StringRef))
 
 ERROR(error_no_output_file_map_specified,none,
       "no output file map specified", ())

lib/Driver/Driver.cpp

@@ -1832,7 +1832,8 @@ Driver::buildOutputFileMap(const llvm::opt::DerivedArgList &Args,
       OutputFileMap::loadFromPath(A->getValue(), workingDirectory);
   if (auto Err = OFM.takeError()) {
     Diags.diagnose(SourceLoc(), diag::error_unable_to_load_output_file_map,
-                   llvm::toString(std::move(Err)));
+                   llvm::toString(std::move(Err)), A->getValue());
+    return None;
   }
   return *OFM;
 }

test/Driver/missing-ofm.swift

@@ -0,0 +1,8 @@
+// Ensure that a bogus output-file-map path does not crash the driver,
+// but instead outputs a nice diagnostic.
+//
+// RUN: %empty-directory(%t)
+// RUN: not %swiftc_driver -c %S/../Inputs/empty.swift -output-file-map %t/something-which-should-not-exist.json 2>&1 | %FileCheck %s
+//
+// CHECK: error: unable to load output file map '{{.*}}/something-which-should-not-exist.json': No such file or directory
+// CHECK-NOT: Assertion failed