[clang] [Driver] Add ExclusiveGroup feature to multilib.yaml. (PR #69447)

[Simon Tatham via cfe-commits]

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+# REQUIRES: shell
+# UNSUPPORTED: system-windows
+
+# RUN: rm -rf %t
+
+# RUN: mkdir -p %t/baremetal_multilib/bin
+# RUN: ln -s %clang %t/baremetal_multilib/bin/clang
+
+# RUN: mkdir -p %t/baremetal_multilib/lib/clang-runtimes
+# RUN: ln -s %s %t/baremetal_multilib/lib/clang-runtimes/multilib.yaml
+
+# RUN: %t/baremetal_multilib/bin/clang -no-canonical-prefixes -x c++ %s -### -o %t.out --target=thumbv7em-none-unknown-eabi --sysroot= 2>%t.err
+
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR1_NON_EXCLUSIVE
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR2_NON_EXCLUSIVE
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR1_EXCLUSIVE
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR2_EXCLUSIVE
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR1_OWN_GROUP
+# RUN: FileCheck -DSYSROOT=%t/baremetal_multilib %s < %t.err --check-prefix=TESTDIR2_OWN_GROUP
+
+# Expected results:
+#
+# Due to the Mappings section, all six of these library directories should
+# match the command-line flag --target=thumbv7em-none-unknown-eabi.
+#
+# The two "non_exclusive" directories, which don't have an ExclusiveGroup at
+# all, should both be selected. So should the two "own_group", each of which
+# specifies a different value of ExclusiveGroup. But the two "exclusive", which
+# have the _same_ ExclusiveGroup value, should not: the second one wins. So we
+# expect five of these six directories to show up in the clang-cc1 command
+# line, but not testdir1_exclusive.
+
+# TESTDIR1_NON_EXCLUSIVE: "-internal-isystem" "[[SYSROOT]]/bin/../lib/clang-runtimes/testdir1_non_exclusive/include/c++/v1"
+# TESTDIR2_NON_EXCLUSIVE: "-internal-isystem" "[[SYSROOT]]/bin/../lib/clang-runtimes/testdir2_non_exclusive/include/c++/v1"
+# TESTDIR2_EXCLUSIVE: "-internal-isystem" "[[SYSROOT]]/bin/../lib/clang-runtimes/testdir2_exclusive/include/c++/v1"
+# TESTDIR1_OWN_GROUP: "-internal-isystem" "[[SYSROOT]]/bin/../lib/clang-runtimes/testdir1_own_group/include/c++/v1"
+# TESTDIR2_OWN_GROUP: "-internal-isystem" "[[SYSROOT]]/bin/../lib/clang-runtimes/testdir2_own_group/include/c++/v1"
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statham-arm wrote:

Thanks. Yes, I agree it would be nice to have a convenient way to share headers in cases where they don't have to vary. But for the cases where they do have to, this feature is still vital. (And for the cases where we just haven't got round to it yet it's still _useful_ :-)

https://github.com/llvm/llvm-project/pull/69447