From a2845bf5cea928ed671ba26a18c02c5b33c1eee8 Mon Sep 17 00:00:00 2001
From: Bryan Chan <bryan.chan@huawei.com>
Date: Sat, 21 Oct 2023 12:49:13 -0400
Subject: [PATCH] [Driver] Handle -Mnomain and -fno-fortran-main correctly

-Mnomain and -fno-fortran-main were ineffective unless they were both used
at the same time. This patch fixes the bug, formats needFortranMain and
needFortranLibs, and adds some test cases for the logic.
---
 clang/lib/Driver/ToolChains/CommonArgs.cpp | 13 ++----
 clang/test/Driver/flang/classic-flang.f95  | 49 ++++++++++++++++++----
 2 files changed, 44 insertions(+), 18 deletions(-)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 5db0dbb8e351..1ccc83a468ce 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -149,19 +149,14 @@ static bool shouldIgnoreUnsupportedTargetFeature(const Arg &TargetFeatureArg,
 #ifdef ENABLE_CLASSIC_FLANG
 /// \brief Determine if Fortran "main" object is needed
 bool tools::needFortranMain(const Driver &D, const ArgList &Args) {
-  return (needFortranLibs(D, Args)
-       && (!Args.hasArg(options::OPT_Mnomain) ||
-           !Args.hasArg(options::OPT_no_fortran_main)));
+  return (needFortranLibs(D, Args) && !Args.hasArg(options::OPT_Mnomain) &&
+          !Args.hasArg(options::OPT_no_fortran_main));
 }
 
 /// \brief Determine if Fortran link libraies are needed
 bool tools::needFortranLibs(const Driver &D, const ArgList &Args) {
-  if (D.IsFlangMode() && !Args.hasArg(options::OPT_nostdlib) &&
-      !Args.hasArg(options::OPT_noFlangLibs)) {
-    return true;
-  }
-
-  return false;
+  return (D.IsFlangMode() && !Args.hasArg(options::OPT_nostdlib) &&
+          !Args.hasArg(options::OPT_noFlangLibs));
 }
 #endif
 
diff --git a/clang/test/Driver/flang/classic-flang.f95 b/clang/test/Driver/flang/classic-flang.f95
index 0319a11358f9..b953ca15e9be 100644
--- a/clang/test/Driver/flang/classic-flang.f95
+++ b/clang/test/Driver/flang/classic-flang.f95
@@ -45,23 +45,29 @@
 ! Check that the linker job is given the correct libraries and library paths.
 
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -mp \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-DYNAMIC-FLANG,CHECK-DYNAMIC-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-DYNAMIC-FLANG,CHECK-DYNAMIC-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -mp -nomp \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-DYNAMIC-FLANG,CHECK-NO-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-DYNAMIC-FLANG,CHECK-NO-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -fopenmp \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-DYNAMIC-FLANG,CHECK-DYNAMIC-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-DYNAMIC-FLANG,CHECK-DYNAMIC-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -fopenmp -fno-openmp \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-DYNAMIC-FLANG,CHECK-NO-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-DYNAMIC-FLANG,CHECK-NO-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -fopenmp -static-openmp \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-DYNAMIC-FLANG,CHECK-STATIC-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-DYNAMIC-FLANG,CHECK-STATIC-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -fopenmp -static-flang-libs \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-STATIC-FLANG,CHECK-DYNAMIC-OMP %s
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-STATIC-FLANG,CHECK-DYNAMIC-OMP %s
 ! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -static-flang-libs \
-! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-STATIC-FLANG,CHECK-NO-OMP %s
-
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-MAIN,CHECK-STATIC-FLANG,CHECK-NO-OMP %s
+! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -Mnomain \
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-NOMAIN,CHECK-DYNAMIC-FLANG %s
+! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -fno-fortran-main \
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-LD,CHECK-NOMAIN,CHECK-DYNAMIC-FLANG %s
 ! CHECK-LD:                "{{.*}}ld{{(.exe)?}}"
 ! CHECK-LD-NOT:            "-static"
-! CHECK-LD:                "{{[^"]*}}classic-flang-{{[^ ]*}}.o" "-lflangmain" "-lfoo" "-L{{[^ ]*[/\\]+}}basic_linux_tree{{[/\\]+}}usr{{[/\\]+}}lib"
+! CHECK-LD-SAME:           "{{[^"]*}}classic-flang-{{[^ ]*}}.o"
+! CHECK-MAIN-SAME:         "-lflangmain"
+! CHECK-NOMAIN-NOT:        "-lflangmain"
+! CHECK-LD-SAME:           "-lfoo" "-L{{[^ ]*[/\\]+}}basic_linux_tree{{[/\\]+}}usr{{[/\\]+}}lib"
 ! CHECK-DYNAMIC-FLANG-NOT: "-Bstatic"
 ! CHECK-DYNAMIC-FLANG:     "-lflang" "-lflangrti" "-lpgmath" "-lpthread" "-lrt" "-lm"
 ! CHECK-DYNAMIC-FLANG-NOT: "-Bdynamic"
@@ -87,3 +93,28 @@
 ! CHECK-STATIC-BOTH-NOT: "-Bstatic"
 ! CHECK-STATIC-BOTH:     "-lomp"
 ! CHECK-STATIC-BOTH-NOT: "-Bdynamic"
+
+! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -no-flang-libs \
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-NOFLANGLIBS %s
+! CHECK-NOFLANGLIBS:      "{{.*}}ld{{(.exe)?}}"
+! CHECK-NOFLANGLIBS-SAME: "{{[^"]*}}classic-flang-{{[^ ]*}}.o"
+! CHECK-NOFLANGLIBS-NOT:  "-lflangmain"
+! CHECK-NOFLANGLIBS-SAME: "-lfoo" "-L{{[^ ]*[/\\]+}}basic_linux_tree{{[/\\]+}}usr{{[/\\]+}}lib"
+! CHECK-NOFLANGLIBS-NOT:  "-lflang" "-lflangrti" "-lpgmath"
+! CHECK-NOFLANGLIBS:      "-lm" "-lgcc"
+! CHECK-NOFLANGLIBS:      "-lgcc_s"
+! CHECK-NOFLANGLIBS:      "-lc"
+
+! In Flang mode, we always link with libm, even with -nostdlib.
+! RUN: %flang -target x86_64-linux-gnu -ccc-install-dir %S/../Inputs/basic_linux_tree/usr/bin -nostdlib \
+! RUN:     %s -lfoo -### 2>&1 | FileCheck --check-prefixes=CHECK-NOSTDLIB %s
+! CHECK-NOSTDLIB:      "{{.*}}ld{{(.exe)?}}"
+! CHECK-NOSTDLIB-SAME: "{{[^"]*}}classic-flang-{{[^ ]*}}.o"
+! CHECK-NOSTDLIB-NOT:  "-lflangmain"
+! CHECK-NOSTDLIB-SAME: "-lfoo" "-L{{[^ ]*[/\\]+}}basic_linux_tree{{[/\\]+}}usr{{[/\\]+}}lib"
+! CHECK-NOSTDLIB-NOT:  "-lflang" "-lflangrti" "-lpgmath"
+! CHECK-NOSTDLIB-NOT:  "-lpthread" "-lrt"
+! CHECK-NOSTDLIB:      "-lm"
+! CHECK-NOSTDLIB-NOT:  "-lgcc"
+! CHECK-NOSTDLIB-NOT:  "-lgcc_s"
+! CHECK-NOSTDLIB-NOT:  "-lc"