Add target-prefixed executables to the installation bin directory

Currently the `bin` directory installed by wasi-sdk is not currently
suitable for putting in `$PATH` in all cases because it can shadow a
system-installed `clang` executable which is intended for native
binaries. For Linux distributions with gcc-based cross-compilers I've
often seen the pattern where they're installed as `$target-gcc` and so
I've taken a leaf out of their books to do that here as well.

This commit adds, currently alongside the preexisting `clang`
executable, target-prefixed executables such as `wasm32-wasi-clang` and
`wasm32-wasi-clang++`. These executables are symlinks to the `clang`
executable itself in the same manner that `clang++` is a symlink to
`clang` itself.

I'll also note that this doesn't fix the problem of "add the wasi-sdk
bin dir to PATH" because `clang` and other prominent executables are
still there. My hope though is that this opens up a future refactoring
for doing so.

Makefile

@@ -42,6 +42,8 @@ override LLVM_CMAKE_FLAGS += -DCMAKE_OSX_ARCHITECTURES="arm64;x86_64" \
 		    -DCMAKE_OSX_DEPLOYMENT_TARGET=10.12
 endif
 
+TARGETS = wasm32-wasi wasm32-wasip1 wasm32-wasip2 wasm32-wasip1-threads wasm32-wasi-threads
+
 # Only the major version is needed for Clang, see https://reviews.llvm.org/D125860.
 CLANG_VERSION=$(shell $(BASH) ./llvm_version_major.sh $(LLVM_PROJ_DIR))
 VERSION:=$(shell $(BASH) ./version.sh)
@@ -51,16 +53,29 @@ default: build
 	@echo "Use -fdebug-prefix-map=$(ROOT_DIR)=wasisdk://v$(VERSION)"
 
 check:
-	CC="clang --sysroot=$(BUILD_PREFIX)/share/wasi-sysroot" \
-	CXX="clang++ --sysroot=$(BUILD_PREFIX)/share/wasi-sysroot -fno-exceptions" \
-	PATH="$(PATH_PREFIX)/bin:$$PATH" tests/run.sh "$(BUILD_PREFIX)" "$(RUNTIME)" "$(ADAPTER)" "$(WASM_TOOLS)"
+	TARGETS="$(TARGETS)" tests/run.sh "$(BUILD_PREFIX)" "$(RUNTIME)" "$(ADAPTER)" "$(WASM_TOOLS)"
 
 clean:
 	rm -rf build $(DESTDIR)
 
+# Default symlinks that clang creates to the `clang` executable
+CLANG_LINKS_TO_CREATE = clang++ clang-cl clang-cpp
+
+# Add target-prefixed versions of `clang` and `clang++` so they can be used
+# without `--target` as it's auto-inferred from the executable name by clang.
+CLANG_LINKS_TO_CREATE += $(foreach target,$(TARGETS),$(target)-clang)
+CLANG_LINKS_TO_CREATE += $(foreach target,$(TARGETS),$(target)-clang++)
+
+# Small helper to create a `join-with` function that can join elements of a
+# list with a defined separator.
+noop =
+space = $(noop) $(noop)
+join-with = $(subst $(space),$1,$(strip $2))
+
 build/llvm.BUILT:
 	mkdir -p build/llvm
 	cd build/llvm && cmake -G Ninja \
+		-DCLANG_LINKS_TO_CREATE="$(call join-with,;,$(CLANG_LINKS_TO_CREATE))" \
 		-DCMAKE_BUILD_TYPE=MinSizeRel \
 		-DLLVM_ENABLE_TERMINFO=OFF \
 		-DLLVM_ENABLE_ZLIB=OFF \

tests/run.sh

@@ -6,13 +6,7 @@ set -ueo pipefail
 # <runwasi> is a WASI-capable runtime to run the tests in full compile and
 # execute mode.
 #
-# By default this script will look for `clang` and `clang++` in $PATH and
-# assume that they are correctly configured with the sysroot in the default
-# location.  Alternatively, exporting $CC and $CXX allow more flexibility. e.g:
-#
-#  export CXX="<wasi-sdk>/bin/clang++ --sysroot <wasi-sdk>/share/wasi-sysroot"
-#  export CC="<wasi-sdk>/bin/clang --sysroot <wasi-sdk>/share/wasi-sysroot"
-#
+# The compiler used during testing is loaded from `<path to wasi-sdk>`.
 if [ $# -lt 1 ]; then
     echo "Path to WASI SDK is required"
     exit 1
@@ -37,44 +31,48 @@ else
 fi
 
 testdir=$(dirname $0)
-CC=${CC:=clang}
-CXX=${CXX:=clang++}
 
-echo $CC
-echo $CXX
 echo "SDK: $wasi_sdk"
 
-for target in wasm32-wasi wasm32-wasip1 wasm32-wasi-threads wasm32-wasip1-threads wasm32-wasip2; do
+# NB: all tests are run with the default `clang` and `clang++` executables
+# but they're also executed with the target-prefixed `clang` executables to
+# ensure that those work as well when the `--target` option is omitted.
+
+for target in $TARGETS; do
     echo "===== Testing target $target ====="
     cd $testdir/compile-only
     for options in -O0 -O2 "-O2 -flto"; do
         echo "===== Testing compile-only with $options ====="
         for file in *.c; do
             echo "Testing compile-only $file..."
-            ../testcase.sh "$target" "" "" "" "$CC" "$options" "$file"
+            ../testcase.sh "$target" "" "" "" "$wasi_sdk/bin/clang" "$options --target=$target" "$file"
+            ../testcase.sh "$target" "" "" "" "$wasi_sdk/bin/$target-clang" "$options" "$file"
         done
         for file in *.cc; do
             echo "Testing compile-only $file..."
-            ../testcase.sh "$target" "" "" "" "$CXX" "$options" "$file"
+            ../testcase.sh "$target" "" "" "" "$wasi_sdk/bin/clang++" "$options --target=$target -fno-exceptions" "$file"
+            ../testcase.sh "$target" "" "" "" "$wasi_sdk/bin/$target-clang++" "$options -fno-exceptions" "$file"
         done
     done
     cd - >/dev/null
-    
+
     cd $testdir/general
     for options in -O0 -O2 "-O2 -flto"; do
         echo "===== Testing with $options ====="
         for file in *.c; do
             echo "Testing $file..."
-            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$CC" "$options" "$file"
+            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$wasi_sdk/bin/clang" "$options --target=$target" "$file"
+            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$wasi_sdk/bin/$target-clang" "$options" "$file"
         done
         for file in *.cc; do
             echo "Testing $file..."
-            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$CXX" "$options" "$file"
+            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$wasi_sdk/bin/clang++" "$options --target=$target -fno-exceptions" "$file"
+            ../testcase.sh "$target" "$runwasi" "$adapter" "$wasm_tools" "$wasi_sdk/bin/$target-clang++" "$options -fno-exceptions" "$file"
         done
     done
     cd - >/dev/null
 done
-    
+
 # Test cmake build system for wasi-sdk
 test_cmake() {
     local option

tests/testcase.sh

@@ -37,7 +37,7 @@ fi
 echo "Testing $input..."
 
 # Compile the testcase.
-$compiler --target=$target $pthread_options $options $file_options "$input" -o "$wasm"
+$compiler $pthread_options $options $file_options "$input" -o "$wasm"
 
 # If we don't have a runwasi command, we're just doing compile-only testing.
 if [ "$runwasi" == "" ]; then
@@ -87,7 +87,7 @@ if [ -e "$input.stdout.expected" ]; then
       stdout_expected="$input.$target.stdout.expected"
   else
       stdout_expected="$input.stdout.expected"
-  fi    
+  fi
 
   # Apply output filters.
   if [ -e "$input.stdout.expected.filter" ]; then
@@ -105,7 +105,7 @@ if [ -e "$input.stderr.expected" ]; then
       stderr_expected="$input.$target.stderr.expected"
   else
       stderr_expected="$input.stderr.expected"
-  fi    
+  fi
 
   # Apply output filters.
   if [ -e "$input.stderr.expected.filter" ]; then