fix: macOS E2E — skip Linux-specific tests + fix portability issues

- run_all.sh: skip tests that assume GCC/ELF/patchelf on macOS
- sed -i → sed -i.bak for macOS compat (05, 09, 22)
- target/x86_64-linux-*/ → target/*/ for platform-portable path (24, 25)

Skipped on macOS (need future Clang/Mach-O adaptation):
  03 (gcm BMI), 07/08 (ELF lib), 09 (gcm BMI), 20/21 (GCC P1689/dyndep),
  22 (GCC fingerprint), 26/27/29 (GCC toolchain), 30 (patchelf), 33 (GCC mangling)

Author: Sunrisepeak

tests/e2e/05_errors.sh

@@ -60,7 +60,7 @@ out=$("$MCPP" build 2>&1) && { echo "expected failure"; exit 1; }
 cd "$TMP"
 "$MCPP" new naming-ok > /dev/null
 cd naming-ok
-sed -i 's/name        = "naming-ok"/name        = "myorg.something"/' mcpp.toml
+sed -i.bak 's/name        = "naming-ok"/name        = "myorg.something"/' mcpp.toml && rm -f mcpp.toml.bak
 cat > src/foo.cppm <<'EOF'
 export module differentprefix;
 import std;

tests/e2e/09_path_dependency.sh

@@ -81,7 +81,7 @@ grep -q 'mcpp.cache/mylibA.greet.gcm\|gcm.cache/mylibA.greet.gcm' "$ninja_file"
 # Path-resolution error reporting: declared name mismatch
 TMP2=$(mktemp -d)
 cp -r "$TMP/mylibA" "$TMP2/wrongname"
-sed -i 's/name        = "mylibA"/name        = "differentname"/' "$TMP2/wrongname/mcpp.toml"
+sed -i.bak 's/name        = "mylibA"/name        = "differentname"/' "$TMP2/wrongname/mcpp.toml" && rm -f "$TMP2/wrongname/mcpp.toml.bak"
 cat > mcpp.toml <<EOF
 [package]
 name        = "myappB"

tests/e2e/22_doctor_cache_publish.sh

@@ -31,7 +31,7 @@ out=$("$MCPP" cache list 2>&1)
 cd "$TMP"
 "$MCPP" new myapp >/dev/null
 cd myapp
-sed -i 's|^repo[[:space:]]*=.*|repo = "https://github.com/example/myapp"|' mcpp.toml
+sed -i.bak 's|^repo[[:space:]]*=.*|repo = "https://github.com/example/myapp"|' mcpp.toml && rm -f mcpp.toml.bak
 grep -q '^repo' mcpp.toml || cat >> mcpp.toml <<'EOF'
 
 [package]

tests/e2e/24_git_dependency.sh

@@ -72,7 +72,7 @@ rev = "$HEAD_REV"
 EOF
 
 "$MCPP" build > build.log 2>&1
-triple=$(ls -d target/x86_64-linux-*/ | head -1)
+triple=$(ls -d target/*/ | head -1)
 fp_dir=$(ls "$triple")
 out=$(${triple}${fp_dir}/bin/myapp)
 [[ "$out" == *"hello from git dep"* ]] || {

tests/e2e/25_convention_mode.sh

@@ -27,7 +27,7 @@ grep -q 'Inferred sources \[src/\*\*'                build.log || { cat build.lo
 grep -q 'Inferred target tinyapp (bin from src/main.cpp)' build.log || { cat build.log; echo "FAIL: no Inferred target line"; exit 1; }
 grep -q 'Compiling tinyapp v0.1.0'                    build.log || { cat build.log; echo "FAIL: not compiling"; exit 1; }
 
-triple=$(ls -d target/x86_64-linux-*/ | head -1)
+triple=$(ls -d target/*/ | head -1)
 fp_dir=$(ls "$triple")
 out=$("${triple}${fp_dir}/bin/tinyapp")
 [[ "$out" == "convention-mode bin OK" ]] || { echo "FAIL: runtime out='$out'"; exit 1; }
@@ -52,7 +52,7 @@ EOF
 "$MCPP" build > build.log 2>&1
 grep -q 'Inferred include_dirs \[include\]' build.log || {
     cat build.log; echo "FAIL: include/ not auto-picked"; exit 1; }
-triple=$(ls -d target/x86_64-linux-*/ | head -1)
+triple=$(ls -d target/*/ | head -1)
 fp_dir=$(ls "$triple")
 out=$("${triple}${fp_dir}/bin/inc")
 [[ "$out" == "answer = 42" ]] || { echo "FAIL: include resolution: $out"; exit 1; }
@@ -101,7 +101,7 @@ EOF
 if grep -q 'Inferred' build.log; then
     cat build.log; echo "FAIL: legacy schema fired Inferred banner unexpectedly"; exit 1
 fi
-triple=$(ls -d target/x86_64-linux-*/ | head -1)
+triple=$(ls -d target/*/ | head -1)
 fp_dir=$(ls "$triple")
 out=$("${triple}${fp_dir}/bin/legacy")
 [[ "$out" == "legacy schema OK" ]] || { echo "FAIL: legacy runtime: $out"; exit 1; }

tests/e2e/run_all.sh

@@ -31,13 +31,58 @@ if [[ -z "${MCPP_HOME:-}" ]]; then
 fi
 echo "MCPP_HOME: $MCPP_HOME"
 
+# Platform detection: some tests are Linux-only (ELF patchelf, musl-static,
+# GCC-specific BMI layout, etc.)
+OS="$(uname -s)"
+MACOS_SKIP=(
+    # GCC-specific BMI assertions (gcm.cache/*.gcm)
+    03_multi_module.sh
+    # Static library test checks ELF ar output format
+    07_static_library.sh
+    # Shared library test hardcodes .so / ELF shared object
+    08_shared_library.sh
+    # Path dependency checks .gcm BMI format (GCC-specific)
+    09_path_dependency.sh
+    # Pack modes use patchelf (ELF-only)
+    30_pack_modes.sh
+    # Toolchain management tests assume GCC availability
+    26_toolchain_management.sh
+    29_toolchain_partial_versions.sh
+    # P1689 scanner test hardcodes GCC ddi format
+    20_p1689_scanner.sh
+    # Ninja dyndep test hardcodes GCC module format
+    21_ninja_dyndep.sh
+    # Doctor/cache/publish uses GCC fingerprint
+    22_doctor_cache_publish.sh
+    # Self-contained home test assumes Linux sandbox layout
+    27_self_contained_home.sh
+    # Multi-version mangling test uses GCC module format
+    33_multi_version_mangling.sh
+)
+
+should_skip() {
+    local name="$1"
+    if [[ "$OS" == "Darwin" ]]; then
+        for skip in "${MACOS_SKIP[@]}"; do
+            [[ "$name" == "$skip" ]] && return 0
+        done
+    fi
+    return 1
+}
+
 PASS=0
 FAIL=0
+SKIP=0
 FAILED_TESTS=()
 
 for test in "$HERE"/[0-9]*.sh; do
     name="$(basename "$test")"
     echo
+    if should_skip "$name"; then
+        echo "SKIP: $name (not applicable on $OS)"
+        ((SKIP++))
+        continue
+    fi
     echo "=== $name ==="
     if MCPP="$MCPP" bash "$test"; then
         echo "PASS: $name"
@@ -51,7 +96,7 @@ done
 
 echo
 echo "==============================================="
-echo "E2E Summary: $PASS passed, $FAIL failed"
+echo "E2E Summary: $PASS passed, $FAIL failed, $SKIP skipped"
 if [[ $FAIL -gt 0 ]]; then
     echo "Failed: ${FAILED_TESTS[@]}"
     exit 1