[clang] d814be1 - [NFC][clang][Driver] Add tests for --driver-mode=flang (#207658)

[via cfe-commits]

Author: Yusuke MINATO
Date: 2026-07-23T11:03:15Z
New Revision: d814be1bb794baf0650158a6bd1dda23f4f86e99

URL: https://github.com/llvm/llvm-project/commit/d814be1bb794baf0650158a6bd1dda23f4f86e99
DIFF: https://github.com/llvm/llvm-project/commit/d814be1bb794baf0650158a6bd1dda23f4f86e99.diff

LOG: [NFC][clang][Driver] Add tests for --driver-mode=flang (#207658)

This patch intends to clarify the current behaviors, not to state the
expected/desirable behaviors.

---------

Co-authored-by: Tarun Prabhu <tarunprabhu at gmail.com>

Added: 
    clang/test/Driver/flang/runtimes.f90

Modified: 
    clang/test/Driver/flang/multiple-inputs-mixed.f90

Removed: 
    


################################################################################
diff  --git a/clang/test/Driver/flang/multiple-inputs-mixed.f90 b/clang/test/Driver/flang/multiple-inputs-mixed.f90
index 98d8cab00bdfd..f6910f3dd9997 100644
--- a/clang/test/Driver/flang/multiple-inputs-mixed.f90
+++ b/clang/test/Driver/flang/multiple-inputs-mixed.f90
@@ -5,3 +5,25 @@
 ! CHECK-SYNTAX-ONLY: "{{[^"]*}}/Inputs/one.f90"
 ! CHECK-SYNTAX-ONLY-LABEL: "{{[^"]*}}clang{{[^"/]*}}" "-cc1"
 ! CHECK-SYNTAX-ONLY: "{{[^"]*}}/Inputs/other.c"
+
+! Check that flang-only options are not passed to clang.
+! RUN: %clang --driver-mode=flang -### -fstack-arrays %S/Inputs/one.f90 %S/Inputs/other.c 2>&1 | FileCheck --check-prefixes=CHECK-FLANG-OPT %s
+! CHECK-FLANG-OPT-LABEL: "{{[^"]*}}flang{{[^"/]*}}" "-fc1"
+! CHECK-FLANG-OPT: "-fstack-arrays"
+! CHECK-FLANG-OPT-LABEL: "{{[^"]*}}clang{{[^"/]*}}" "-cc1"
+! CHECK-FLANG-OPT-NOT: "-fstack-arrays"
+
+! The -std= option is accepted by both clang and flang, but its acceptable values 
diff er between the two.
+! Currently, -std=c17 is passed to flang, which rejects it. This should be fixed in the future.
+! A potential solution is to use -Xflang and -Xclang to pass the option to the right frontend; however, -Xclang is rejected.
+
+! RUN: %clang --driver-mode=flang -### -std=f2018 %S/Inputs/one.f90 -std=c17 %S/Inputs/other.c 2>&1 | FileCheck --check-prefixes=MIXED-OPT %s
+! MIXED-OPT-LABEL: "{{[^"]*}}flang{{[^"/]*}}" "-fc1"
+! MIXED-OPT: "-std=f2018"
+! MIXED-OPT: "-std=c17"
+! MIXED-OPT-LABEL: "{{[^"]*}}clang{{[^"/]*}}" "-cc1"
+! MIXED-OPT-NOT: "-std=f2018"
+! MIXED-OPT: "-std=c17"
+
+! RUN: not %clang --driver-mode=flang -### -Xflang -std=f2018 %S/Inputs/one.f90 -Xclang -std=c17 %S/Inputs/other.c 2>&1 | FileCheck --check-prefixes=SEPARATE-MIXED-OPT %s
+! SEPARATE-MIXED-OPT: error: unknown argument '-Xclang'

diff  --git a/clang/test/Driver/flang/runtimes.f90 b/clang/test/Driver/flang/runtimes.f90
new file mode 100644
index 0000000000000..b979a86c2f7c6
--- /dev/null
+++ b/clang/test/Driver/flang/runtimes.f90
@@ -0,0 +1,8 @@
+! Check that Flang runtimes are passed to the linker in --driver-mode=flang.
+
+! RUN: %clang --driver-mode=flang --rtlib=compiler-rt -### %s 2>&1 | FileCheck %s
+! CHECK-DAG: clang_rt.{{[^ "]}}
+! CHECK-DAG: flang_rt.{{[^ "]}}
+
+! RUN: not %clang --driver-mode=flang -stdlib=libc++ -### %s 2>&1 | FileCheck --check-prefix=LIBCXX %s
+! LIBCXX: error: unknown argument: '-stdlib=libc++'