[flang] Search for #include "file" in right directory (take 2)

Make the #include "file" preprocessing directive begin its
search in the same directory as the file containing the directive,
as other preprocessors and our Fortran INCLUDE statement do.

Avoid current working directory for all source files except the original.

Resolve tests.

Differential Revision: https://reviews.llvm.org/D95481

1 files changed, 10 insertions, 1 deletions

diff --git a/flang/lib/Parser/preprocessor.cpp b/flang/lib/Parser/preprocessor.cpp
index c5422cc..d3dd50a 100644
--- a/flang/lib/Parser/preprocessor.cpp
+++ b/flang/lib/Parser/preprocessor.cpp
@@ -399,6 +399,7 @@ void Preprocessor::Directive(const TokenSequence &dir, Prescanner *prescanner) {
   if (j == tokens) {
     return;
   }
+  CHECK(prescanner); // TODO: change to reference
   if (dir.TokenAt(j).ToString() != "#") {
     prescanner->Say(dir.GetTokenProvenanceRange(j), "missing '#'"_err_en_US);
     return;
@@ -578,6 +579,7 @@ void Preprocessor::Directive(const TokenSequence &dir, Prescanner *prescanner) {
       return;
     }
     std::string include;
+    std::optional<std::string> prependPath;
     if (dir.TokenAt(j).ToString() == "<") { // #include <foo>
       std::size_t k{j + 1};
       if (k >= tokens) {
@@ -598,6 +600,12 @@ void Preprocessor::Directive(const TokenSequence &dir, Prescanner *prescanner) {
     } else if ((include = dir.TokenAt(j).ToString()).substr(0, 1) == "\"" &&
         include.substr(include.size() - 1, 1) == "\"") { // #include "foo"
       include = include.substr(1, include.size() - 2);
+      // #include "foo" starts search in directory of file containing
+      // the directive
+      auto prov{dir.GetTokenProvenanceRange(dirOffset).start()};
+      if (const auto *currentFile{allSources_.GetSourceFile(prov)}) {
+        prependPath = DirectoryName(currentFile->path());
+      }
     } else {
       prescanner->Say(dir.GetTokenProvenanceRange(j < tokens ? j : tokens - 1),
           "#include: expected name of file to include"_err_en_US);
@@ -615,7 +623,8 @@ void Preprocessor::Directive(const TokenSequence &dir, Prescanner *prescanner) {
     }
     std::string buf;
     llvm::raw_string_ostream error{buf};
-    const SourceFile *included{allSources_.Open(include, error)};
+    const SourceFile *included{
+        allSources_.Open(include, error, std::move(prependPath))};
     if (!included) {
       prescanner->Say(dir.GetTokenProvenanceRange(dirOffset),
           "#include: %s"_err_en_US, error.str());