From d6dc544140f4b089d59710bb9aaa7f674e623b37 Mon Sep 17 00:00:00 2001
From: Sebastian Wilzbach <seb@wilzba.ch>
Date: Mon, 25 Dec 2017 23:29:59 +0100
Subject: [PATCH] Avoid creation of a temporary probe file for newer compilers

---
 source/dub/compilers/compiler.d | 48 ++++++++++++++++++++++++++++-----
 source/dub/compilers/utils.d    | 22 ++++++++++-----
 2 files changed, 57 insertions(+), 13 deletions(-)

diff --git a/source/dub/compilers/compiler.d b/source/dub/compilers/compiler.d
index 2670bcf317..061de5d18a 100644
--- a/source/dub/compilers/compiler.d
+++ b/source/dub/compilers/compiler.d
@@ -115,19 +115,53 @@ interface Compiler {
 		enforce(status == 0, format("%s failed with exit code %s.", args[0], status));
 	}
 
+	/** Detect the frontend version of a compiler_binary
+	    Returns: 0 if the detection failed, otherwise the frontend version.
+		Note: This only works for DMD and LDC.
+	 */
+	private int frontendVersion(string compiler_binary)
+	{
+		import std.range : dropOne;
+
+		auto res = execute([compiler_binary, "--version"]);
+		if (res.status == 0) {
+			auto versionRange = res.output.find("DMD64 D Compiler v").splitter(".");
+			if (!versionRange.empty && !versionRange.dropOne.empty) {
+				return versionRange.dropOne.front.to!int;
+			}
+		}
+		return 0;
+	}
+
+	// DMD 2.076.0 and newer support passing files via stdin
+	private bool canUseStdin(string compiler_binary)
+	{
+		return frontendVersion(compiler_binary) >= 76 && compiler_binary.startsWith("dmd");
+	}
+
 	/// Compiles platform probe file with the specified compiler and parses its output.
 	protected final BuildPlatform probePlatform(string compiler_binary, string[] args, string arch_override)
 	{
 		import std.string : format;
-		import dub.compilers.utils : generatePlatformProbeFile, readPlatformProbe;
+		import dub.compilers.utils : generatePlatformProbeFile, readPlatformProbe, platformProbeFile;
 
-		auto fil = generatePlatformProbeFile();
+		bool canUseStdin = this.canUseStdin(compiler_binary);
+		string fil = canUseStdin ? generatePlatformProbeFile().toNativeString() : "-";
 
-		auto result = executeShell(escapeShellCommand(compiler_binary ~ args ~ fil.toNativeString()));
-		enforce(result.status == 0, format("Failed to invoke the compiler %s to determine the build platform: %s",
-				compiler_binary, result.output));
-
-		auto build_platform = readPlatformProbe(result.output);
+		auto p = pipeShell(escapeShellCommand(compiler_binary ~ args ~ fil), Redirect.all);
+		if (canUseStdin) {
+			p.stdin.write(platformProbeFile);
+			p.stdin.close;
+		}
+		// read stdout
+		string output;
+		auto app = appender!(ubyte[]);
+    	p.stderr.byChunk(4096).each!(a => app.put(a));
+    	output = cast(string) app.data;
+		enforce(p.pid.wait== 0, format("Failed to invoke the compiler %s to determine the build platform: %s",
+				compiler_binary, output));
+
+		auto build_platform = readPlatformProbe(output);
 		build_platform.compilerBinary = compiler_binary;
 
 		if (build_platform.compiler != this.name) {
diff --git a/source/dub/compilers/utils.d b/source/dub/compilers/utils.d
index 81983ee4f5..0062cf1f59 100644
--- a/source/dub/compilers/utils.d
+++ b/source/dub/compilers/utils.d
@@ -255,7 +255,21 @@ NativePath generatePlatformProbeFile()
 		fil.close();
 	}
 
-	fil.write(q{
+	fil.write(platformProbeFile);
+	fil.close();
+
+	return path;
+}
+
+
+/**
+	Platform probe file that will give, at compile time, information about the compiler (architecture, frontend version...)
+
+	See_Also: `generatePlatformProbeFile`, `readPlatformProbe`
+*/
+string platformProbeFile()
+{
+	return q{
 		module dub_platform_probe;
 		import std.array;
 
@@ -279,11 +293,7 @@ NativePath generatePlatformProbeFile()
 		string determineArchitecture() } ~ '{' ~ archCheck ~
 		`	return '"' ~ ret.data.join("\", \"") ~ "\", "; }` ~ q{
 
-		string determineCompiler() } ~ '{' ~ compilerCheck ~ "	}");
-
-	fil.close();
-
-	return path;
+		string determineCompiler() } ~ '{' ~ compilerCheck ~ "	}";
 }
 
 /**