main: use wasm-ld instead of wasm-ld-8 on macOS

This commit does a few things:
  * remove the -8 suffix on macOS, where it is not necessary
  * add smoke tests for compiling wasm files on Linux and macOS

.circleci/config.yml

@@ -66,6 +66,7 @@ commands:
       - run: tinygo build -size short -o test.elf -target=pca10056            examples/blinky2
       - run: tinygo build -size short -o test.elf -target=itsybitsy-m0        examples/blinky1
       - run: tinygo build -size short -o test.elf -target=circuitplay-express examples/blinky1
+      - run: tinygo build             -o wasm.wasm -target=wasm               examples/wasm
   test-linux:
     parameters:
       llvm:

.travis.yml

@@ -38,3 +38,4 @@ script:
   - tinygo build -size short -o blinky1.pca10056.elf    -target=pca10056     examples/blinky1
   - tinygo build -size short -o blinky2.pca10056.elf    -target=pca10056     examples/blinky2
   - tinygo build -size short -o blinky1.samd21.elf    -target=itsybitsy-m0     examples/blinky1
+  - tinygo build             -o wasm.wasm          -target=wasm         examples/wasm

commands_macos.go

@@ -7,5 +7,5 @@ var commands = map[string]string{
 	"ar":      "llvm-ar",
 	"clang":   "clang-8",
 	"ld.lld":  "ld.lld-8",
-	"wasm-ld": "wasm-ld-8",
+	"wasm-ld": "wasm-ld",
 }

main.go

@@ -228,7 +228,11 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		}
 
 		// Link the object files together.
+		if linker, ok := commands[spec.Linker]; ok {
+			err = Link(sourceDir(), linker, ldflags...)
+		} else {
 			err = Link(sourceDir(), spec.Linker, ldflags...)
+		}
 		if err != nil {
 			return &commandError{"failed to link", executable, err}
 		}

targets/wasm.json

@@ -4,7 +4,7 @@
 	"goos":          "js",
 	"goarch":        "wasm",
 	"compiler":      "clang-8",
-	"linker":        "wasm-ld-8",
+	"linker":        "wasm-ld",
 	"cflags": [
 		"--target=wasm32",
 		"-Oz"