[flang][driver] Add default intrinsic module path in f18 to make f18 behave like flang-new (with respect to the module paths), make it possible to share more tests between the drivers and make using f18 easier (the default path means that users are no longer required to specify it)

Reviewed By: awarzynski

Differential Revision: https://reviews.llvm.org/D99336

GitOrigin-RevId: d0d92fee6f41c0f3c18a1644d4d7ac5d58f63586
diff --git a/test/Driver/intrinsic_module_path.f90 b/test/Driver/intrinsic_module_path.f90
index 3f11512..1105220 100644
--- a/test/Driver/intrinsic_module_path.f90
+++ b/test/Driver/intrinsic_module_path.f90
@@ -3,20 +3,11 @@
 ! With the option GIVEN, the module with the same name is PREPENDED, and considered over the
 ! default one, causing a CHECKSUM error.
 
-! REQUIRES: new-flang-driver
-
-
-!--------------------------
-! FLANG DRIVER (flang-new)
-!--------------------------
-! RUN: %flang-new -fsyntax-only %s  2>&1 | FileCheck %s --allow-empty --check-prefix=WITHOUT
-! RUN: not %flang-new -fsyntax-only -fintrinsic-modules-path %S/Inputs/ %s  2>&1 | FileCheck %s --check-prefix=GIVEN
-
 !-----------------------------------------
 ! FRONTEND FLANG DRIVER (flang-new -fc1)
 !-----------------------------------------
-! RUN: %flang-new -fc1 %s  2>&1 | FileCheck %s --allow-empty --check-prefix=WITHOUT
-! RUN: not %flang-new -fc1 -fintrinsic-modules-path %S/Inputs/ %s  2>&1 | FileCheck %s --check-prefix=GIVEN
+! RUN: %flang_fc1 -fsyntax-only %s  2>&1 | FileCheck %s --allow-empty --check-prefix=WITHOUT
+! RUN: not %flang_fc1 -fsyntax-only -fintrinsic-modules-path %S/Inputs/ %s  2>&1 | FileCheck %s --check-prefix=GIVEN
 
 !-----------------------------------------
 ! EXPECTED OUTPUT WITHOUT
diff --git a/test/lit.cfg.py b/test/lit.cfg.py
index 4392da6..7c99d6f 100644
--- a/test/lit.cfg.py
+++ b/test/lit.cfg.py
@@ -64,7 +64,6 @@
 # the build directory holding that tool.
 tools = [
   ToolSubst('%f18', command=FindTool('f18'),
-    extra_args=["-intrinsic-module-directory "+config.flang_intrinsic_modules_dir],
     unresolved='fatal')
 ]
 
@@ -75,10 +74,8 @@
     extra_args=['-fc1'], unresolved='fatal'))
 else:
    tools.append(ToolSubst('%flang', command=FindTool('f18'),
-    extra_args=["-intrinsic-module-directory "+config.flang_intrinsic_modules_dir],
     unresolved='fatal'))
    tools.append(ToolSubst('%flang_fc1', command=FindTool('f18'),
-    extra_args=["-intrinsic-module-directory "+config.flang_intrinsic_modules_dir],
     unresolved='fatal'))
 
 if config.flang_standalone_build:
diff --git a/tools/f18/f18.cpp b/tools/f18/f18.cpp
index e22905a..9c5e6c9 100644
--- a/tools/f18/f18.cpp
+++ b/tools/f18/f18.cpp
@@ -27,6 +27,7 @@
 #include "flang/Version.inc"
 #include "llvm/Support/Errno.h"
 #include "llvm/Support/FileSystem.h"
+#include "llvm/Support/FileUtilities.h"
 #include "llvm/Support/Program.h"
 #include "llvm/Support/Signals.h"
 #include "llvm/Support/raw_ostream.h"
@@ -395,6 +396,16 @@
   return exitStatus;
 }
 
+// Generate the path to look for intrinsic modules
+static std::string getIntrinsicDir() {
+  // TODO: Find a system independent API
+  llvm::SmallString<128> driverPath;
+  driverPath.assign(llvm::sys::fs::getMainExecutable(nullptr, nullptr));
+  llvm::sys::path::remove_filename(driverPath);
+  driverPath.append("/../include/flang/");
+  return std::string(driverPath);
+}
+
 int main(int argc, char *const argv[]) {
 
   atexit(CleanUpAtExit);
@@ -431,6 +442,10 @@
   std::vector<std::string> fortranSources, otherSources;
   bool anyFiles{false};
 
+  // Add the default intrinsic module directory to the list of search
+  // directories
+  driver.searchDirectories.push_back(getIntrinsicDir());
+
   while (!args.empty()) {
     std::string arg{std::move(args.front())};
     auto dot{arg.rfind(".")};
@@ -603,8 +618,11 @@
     } else if (arg == "-module-suffix") {
       driver.moduleFileSuffix = args.front();
       args.pop_front();
-    } else if (arg == "-intrinsic-module-directory") {
-      driver.searchDirectories.push_back(args.front());
+    } else if (arg == "-intrinsic-module-directory" ||
+        arg == "-fintrinsic-modules-path") {
+      // prepend to the list of search directories
+      driver.searchDirectories.insert(
+          driver.searchDirectories.begin(), args.front());
       args.pop_front();
     } else if (arg == "-futf-8") {
       driver.encoding = Fortran::parser::Encoding::UTF_8;
diff --git a/tools/f18/flang b/tools/f18/flang
index 8dda836..81fac7b 100644
--- a/tools/f18/flang
+++ b/tools/f18/flang
@@ -8,7 +8,7 @@
 #===------------------------------------------------------------------------===#
 
 wd=$(cd $(dirname "$0")/.. && pwd)
-opts="-module-suffix .f18.mod -intrinsic-module-directory $wd/include/flang"
+opts="-module-suffix .f18.mod "
 if ! $wd/bin/f18 $opts "$@"
 then status=$?
      echo flang: in $PWD, f18 failed with exit status $status: $wd/bin/f18 $opts "$@" >&2