druntime-test: Detect musl more robustly

Try to detect musl on more systems than just Alpine.

This also fixes an issue in the Github runners where the default shell
is dash which doesn't understand the `&>` operator leading to the
musl-excluded tests to also be skipped on glibc linux.

Signed-off-by: Andrei Horodniceanu <a.horodniceanu@proton.me>

Author: the-horo

druntime/Makefile

@@ -497,10 +497,15 @@ $(addsuffix /.run,$(filter-out test/shared,$(ADDITIONAL_TESTS))): $(DRUNTIME)
 test/shared/.run: $(DRUNTIMESO)
 endif
 
+ifeq (linux,$(OS))
+    LDD = ldd
+    IS_MUSL != $(LDD) --version 2>&1 | grep -q musl && echo 1
+endif
+
 test/%/.run: test/%/Makefile $(DMD)
 	$(QUIET)$(MAKE) -C test/$* MODEL=$(MODEL) OS=$(OS) DMD=$(abspath $(DMD)) BUILD=$(BUILD) \
 		DRUNTIME=$(abspath $(DRUNTIME)) DRUNTIMESO=$(abspath $(DRUNTIMESO)) LINKDL=$(LINKDL) \
-		QUIET=$(QUIET) TIMELIMIT='$(TIMELIMIT)' PIC=$(PIC) SHARED=$(SHARED)
+		QUIET=$(QUIET) TIMELIMIT='$(TIMELIMIT)' PIC=$(PIC) SHARED=$(SHARED) IS_MUSL=$(IS_MUSL)
 
 test/%/.clean: test/%/Makefile
 	$(QUIET)$(MAKE) -C test/$* MODEL=$(MODEL) OS=$(OS) BUILD=$(BUILD) clean

druntime/test/exceptions/Makefile

@@ -1,16 +1,9 @@
-ifeq ($(OS),linux)
-    # FIXME: detect musl libc robustly; just checking Alpine Linux' apk tool for now
-    ifeq (1,$(shell which apk &>/dev/null && echo 1))
-        IS_MUSL:=1
-    endif
-endif
-
 TESTS=stderr_msg unittest_assert invalid_memory_operation static_dtor \
       future_message refcounted rt_trap_exceptions_drt catch_in_finally \
       message_with_null
 
 # FIXME: segfaults with musl libc
-ifneq ($(IS_MUSL),1)
+ifndef IS_MUSL
 TESTS += unknown_gc
 endif
 
@@ -26,7 +19,7 @@ GDB:=gdb
 ifeq ($(OS),linux)
     TESTS+=line_trace line_trace_21656 long_backtrace_trunc rt_trap_exceptions cpp_demangle
     # registerMemoryAssertHandler requires glibc
-    ifneq ($(IS_MUSL),1)
+    ifndef IS_MUSL
         TESTS+=memoryerror_null_read memoryerror_null_write memoryerror_null_call memoryerror_stackoverflow
     endif
     line_trace_dflags:=-L--export-dynamic

druntime/test/importc_compare/Makefile

@@ -2,10 +2,8 @@ TESTS := importc_compare
 
 # FIXME: fails on Alpine v3.21 with conflicting struct declarations in the C headers:
 # /usr/include/asm-generic/fcntl.h(195): Error: struct `importc_includes.flock` conflicts with struct `importc_includes.flock` at /usr/include/fcntl.h(24)
-ifeq ($(OS),linux)
-    ifeq (1,$(shell which apk &>/dev/null && echo 1))
-        TESTS :=
-    endif
+ifdef IS_MUSL
+    TESTS :=
 endif
 
 include ../common.mak