[flang][driver] Add default intrinsic module path in f18

[arnamoy10]

Summary

f18 currently does not have a default path for intrinsic modules. The default path was provided through command-line option. This patch

1. Adds the default intrinsic modules path in the search directories first
2. Prepends the intrinsic module directory path (if supplied) to the list of search directories
3. Adds an alias fintrinsic-modules-path in f18
4. Removes the added option for providing intrinsic module path from the test config files
5. Update the test case to run for both flang and f18.

The motivations for this patch includes:

1. Make f18 behave like flang-new (with respect to the module paths)
2. Make it possible to share more tests between the drivers
3. Make using f18 easier (the default path means that users are no longer required to specify it)

[arnamoy10]

Adding an alias fintrinsic-modules-path in f18 and removing part of the test to make the test shareable.

[awarzynski]

With this patch we can share more tests between the drivers and their behavior with respect to module paths becomes more consistent. Great to see this, thank you @arnamoy10 !

flang/test/Driver/intrinsic_module_path.f90

 ! Ensure argument -fintrinsic-modules-path works as expected.
 ! WITHOUT the option, the default location for the module is checked and no error generated.
 ! 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
 !-----------------------------------------
 ! WITHOUT-NOT: 'ieee_arithmetic.mod' was not found
 ! WITHOUT-NOT: 'iso_fortran_env.mod' was not found
 
 !-----------------------------------------

flang/test/lit.cfg.py

if config.flang_llvm_tools_dir != "":
         config.available_features.add('fir')
         if config.llvm_tools_dir != config.flang_llvm_tools_dir:
             llvm_config.with_environment('PATH', config.flang_llvm_tools_dir, append_path=True)
 
 # For each occurrence of a flang tool name, replace it with the full path to
 # the build directory holding that tool.
 tools = [
   ToolSubst('%f18', command=FindTool('f18'),
-    extra_args=["-intrinsic-module-directory "+config.flang_intrinsic_modules_dir],
     unresolved='fatal')
 ]
 
 if config.include_flang_new_driver_test:
    tools.append(ToolSubst('%flang-new', command=FindTool('flang-new'), unresolved='fatal'))
    tools.append(ToolSubst('%flang', command=FindTool('flang-new'), unresolved='fatal'))
    tools.append(ToolSubst('%flang_fc1', command=FindTool('flang-new'),
     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:
     llvm_config.add_tool_substitutions(tools, [config.flang_llvm_tools_dir])
 else:
     llvm_config.add_tool_substitutions(tools, config.llvm_tools_dir)
 
 # Enable libpgmath testing
 result = lit_config.params.get("LIBPGMATH")
 if result:
     config.environment["LIBPGMATH"] = True

flang/tools/f18/f18.cpp

 #include "flang/Parser/unparse.h"
 #include "flang/Semantics/expression.h"
 #include "flang/Semantics/runtime-type-info.h"
 #include "flang/Semantics/semantics.h"
 #include "flang/Semantics/unparse-with-symbols.h"
 #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"
 #include <cstdio>
 #include <cstring>
 #include <fstream>
 #include <list>
 #include <memory>

 }
 
 int printVersion() {
   llvm::errs() << "\nf18 compiler (under development), version "
                << FLANG_VERSION_STRING << "\n";
   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);
 
   DriverOptions driver;
   const char *F18_FC{getenv("F18_FC")};
   driver.F18_FCArgs.push_back(F18_FC ? F18_FC : "gfortran");
   bool isPGF90{driver.F18_FCArgs.back().rfind("pgf90") != std::string::npos};
#if __x86_64__
   predefinitions.emplace_back("__x86_64__", "1");
 #endif
 
   Fortran::common::IntrinsicTypeDefaultKinds defaultKinds;
 
   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(".")};
     std::string suffix{arg.substr(dot + 1)};
     std::string prefix{arg.substr(0, 2)};
     args.pop_front();
     if (arg.empty()) {
     } else if (arg.at(0) != '-') {
if (arg.empty()) {
       args.pop_front();
     } else if (arg == "-module-dir") {
       driver.moduleDirectory = args.front();
       driver.searchDirectories.push_back(driver.moduleDirectory);
       args.pop_front();
     } 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;
     } else if (arg == "-flatin") {
       driver.encoding = Fortran::parser::Encoding::LATIN_1;
     } else if (arg == "-fget-definition") {
       // Receives 3 arguments: line, startColumn, endColumn.
       options.needProvenanceRangeToCharBlockMappings = true;

flang/tools/f18/flang

 #!/bin/bash
 #===-- tools/f18/flang.sh -----------------------------------------*- sh -*-===#
 #
 # Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 # See https://llvm.org/LICENSE.txt for license information.
 # SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 #
 #===------------------------------------------------------------------------===#
 
 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
      exit $status
 fi