From 64ea224aceb6cd4b1b83f7fc1cad23ecce2c5cf5 Mon Sep 17 00:00:00 2001
From: peter klausler <pklausler@nvidia.com>
Date: Tue, 3 Dec 2019 09:49:44 -0800
Subject: [PATCH] [flang] Fix bug flang-compiler/f18#843, bad recovery from
 failed opens of source files

Original-commit: flang-compiler/f18@27d9db610fc7302b8da33e19a70c441a0ead6c7c
Reviewed-on: https://github.com/flang-compiler/f18/pull/850
---
 flang/lib/parser/parsing.cc     |  1 +
 flang/lib/parser/provenance.cc  |  7 +++++--
 flang/lib/semantics/mod-file.cc | 10 +++++-----
 3 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/flang/lib/parser/parsing.cc b/flang/lib/parser/parsing.cc
index c93e2d3e7e65..30b405580596 100644
--- a/flang/lib/parser/parsing.cc
+++ b/flang/lib/parser/parsing.cc
@@ -49,6 +49,7 @@ const SourceFile *Parsing::Prescan(const std::string &path, Options options) {
     messages_.Say(range, "%s"_err_en_US, fileError.str());
     return sourceFile;
   }
+  CHECK(sourceFile);
   if (sourceFile->bytes() == 0) {
     ProvenanceRange range{allSources.AddCompilerInsertion(path)};
     messages_.Say(range, "file is empty"_err_en_US);
diff --git a/flang/lib/parser/provenance.cc b/flang/lib/parser/provenance.cc
index d769dac846b0..279e6fa399a9 100644
--- a/flang/lib/parser/provenance.cc
+++ b/flang/lib/parser/provenance.cc
@@ -174,8 +174,11 @@ std::string AllSources::PopSearchPathDirectory() {
 
 const SourceFile *AllSources::Open(std::string path, std::stringstream *error) {
   std::unique_ptr<SourceFile> source{std::make_unique<SourceFile>(encoding_)};
-  source->Open(LocateSourceFile(path, searchPath_), error);
-  return ownedSourceFiles_.emplace_back(std::move(source)).get();
+  if (source->Open(LocateSourceFile(path, searchPath_), error)) {
+    return ownedSourceFiles_.emplace_back(std::move(source)).get();
+  } else {
+    return nullptr;
+  }
 }
 
 const SourceFile *AllSources::ReadStandardInput(std::stringstream *error) {
diff --git a/flang/lib/semantics/mod-file.cc b/flang/lib/semantics/mod-file.cc
index 4b2721546102..2d557e14e939 100644
--- a/flang/lib/semantics/mod-file.cc
+++ b/flang/lib/semantics/mod-file.cc
@@ -764,16 +764,16 @@ Scope *ModFileReader::Read(const SourceName &name, Scope *ancestor) {
   options.searchDirectories = context_.searchDirectories();
   auto path{ModFileName(name, ancestorName, context_.moduleFileSuffix())};
   const auto *sourceFile{parsing.Prescan(path, options)};
-  if (!sourceFile) {
-    return nullptr;
-  } else if (parsing.messages().AnyFatalError()) {
+  if (parsing.messages().AnyFatalError()) {
     for (auto &msg : parsing.messages().messages()) {
       std::string str{msg.ToString()};
       Say(name, ancestorName, parser::MessageFixedText{str.c_str(), str.size()},
-          sourceFile->path());
+          path);
     }
     return nullptr;
-  } else if (!VerifyHeader(sourceFile->content(), sourceFile->bytes())) {
+  }
+  CHECK(sourceFile);
+  if (!VerifyHeader(sourceFile->content(), sourceFile->bytes())) {
     Say(name, ancestorName, "File has invalid checksum: %s"_en_US,
         sourceFile->path());
     return nullptr;