[clang] [Driver] Improve error when a compiler-rt library is not found (PR #81037)

[Jon Roelofs via cfe-commits]

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@@ -44,9 +43,8 @@
 // CHECK-V6M-DEFAULTCXX: "-resource-dir" "[[RESOURCE_DIR:[^"]+]]"
 // CHECK-V6M-DEFAULTCXX: ld{{(.exe)?}}" "{{.*}}.o" "-Bstatic" "-EL"
 // CHECK-V6M-DEFAULTCXX-SAME: "-L{{[^"]*}}{{[/\\]+}}Inputs{{[/\\]+}}baremetal_arm{{[/\\]+}}lib"
-// CHECK-V6M-DEFAULTCXX-SAME: "-L[[RESOURCE_DIR]]{{[/\\]+}}lib{{[/\\]+}}baremetal"
 // CHECK-V6M-DEFAULTCXX-SAME: "-lc++" "-lc++abi" "-lunwind"
-// CHECK-V6M-DEFAULTCXX-SAME: "-lc" "-lm" "-lclang_rt.builtins-armv6m" "--target2=rel" "-o" "a.out"
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jroelofs wrote:

ISTM the more "correct" way to fix this test is to create an empty file `libclang_rt.builtins-armv6m.a` in the fake resource dir.  The folder structure should match what you get from `clang/cmake/caches/BaremetalARM.cmake` (assuming that cache isn't completely bit-rotten)

https://github.com/llvm/llvm-project/pull/81037