Pass -fsyntax-only when getting GCC options and test that -masm= is really supported (#2001)

* Pass -fsyntax-only when getting GCC options

Without this, the gcc driver will still attempt to invoke the assembler,
even though it is redundant to do so.

* Test that -masm= is both available and supported.

Targets such as i686-apple-darwin or x86_64-apple-darwin may have
-masm=intel present in --target-help, but any use of it will throw:

    error: ‘-masm=intel’ not supported in this configuration

1 files changed, 20 insertions, 5 deletions

diff --git a/lib/compilers/argument-parsers.js b/lib/compilers/argument-parsers.js
index 03ddc30c1..660995ab5 100644
--- a/lib/compilers/argument-parsers.js
+++ b/lib/compilers/argument-parsers.js
@@ -82,16 +82,22 @@ class BaseParser {
 class GCCParser extends BaseParser {
     static async parse(compiler) {
         const results = await Promise.all([
-            GCCParser.getOptions(compiler, "--target-help"),
-            GCCParser.getOptions(compiler, "--help=common"),
-            GCCParser.getOptions(compiler, "--help=optimizers")
+            GCCParser.getOptions(compiler, "-fsyntax-only --target-help"),
+            GCCParser.getOptions(compiler, "-fsyntax-only --help=common"),
+            GCCParser.getOptions(compiler, "-fsyntax-only --help=optimizers")
         ]);
         const options = Object.assign({}, ...results);
         const keys = _.keys(options);
         logger.debug(`gcc-like compiler options: ${keys.join(" ")}`);
         if (BaseParser.hasSupport(options, "-masm=")) {
-            compiler.compiler.intelAsm = "-masm=intel";
-            compiler.compiler.supportsIntel = true;
+            // -masm= may be available but unsupported by the compiler.
+            compiler.exec(compiler.compiler.exe, ["-fsyntax-only", "--target-help", "-masm=intel"])
+                .then(result => {
+                    if (result.code === 0) {
+                        compiler.compiler.intelAsm = "-masm=intel";
+                        compiler.compiler.supportsIntel = true;
+                    }
+                });
         }
         if (BaseParser.hasSupport(options, "-fdiagnostics-color")) {
             if (compiler.compiler.options) compiler.compiler.options += " ";
@@ -103,6 +109,15 @@ class GCCParser extends BaseParser {
         }
         return compiler;
     }
+
+    static async getOptions(compiler, helpArg) {
+        const optionFinder = /^\s*(--?[a-z0-9=+,[\]<>|-]*)\s*(.*)/i;
+        const result = await compiler.execCompilerCached(compiler.compiler.exe, helpArg.split(' '));
+        const options = result.code === 0
+            ? BaseParser.parseLines(result.stdout + result.stderr, optionFinder) : {};
+        compiler.possibleArguments.populateOptions(options);
+        return options;
+    }
 }
 
 class ClangParser extends BaseParser {