msvc: fix detect_showincludes_prefix with MSBuild

.github/workflows/integration-tests.yml

@@ -514,6 +514,19 @@ jobs:
           $SCCACHE_EXE "$(where cl.exe)" -c "@args.rsp"
           $SCCACHE_EXE --show-stats
 
+      - name: Prepare - MSBuild support
+        shell: bash
+        working-directory: ./tests/msvc-msbuild
+        # Force stop server to drop compiler cache - need to test showInclude prefix detection
+        run: |
+          $SCCACHE_EXE --stop-server
+          mkdir -p compiler
+          cp $SCCACHE_EXE compiler/cl.exe
+
+      - name: Compile - MSBuild support
+        working-directory: ./tests/msvc-msbuild
+        run: msbuild MsbuildCpp.vcxproj -property:Configuration=Release -property:Platform=x64 "-property:SolutionDir=${{ github.workspace }}/tests/msvc-msbuild/"
+
       - name: Stop Server
         if: success() || failure()
         shell: bash

src/compiler/compiler.rs

@@ -1965,7 +1965,7 @@ mod test {
             s = &s[4..];
         }
         let prefix = String::from("blah: ");
-        let stdout = format!("{}{}\r\n", prefix, s);
+        let stderr = format!("{}{}\r\n", prefix, s);
         // Compiler detection output
         next_command(
             &creator,
@@ -1982,7 +1982,7 @@ mod test {
         // showincludes prefix detection output
         next_command(
             &creator,
-            Ok(MockChild::new(exit_status(0), stdout, String::new())),
+            Ok(MockChild::new(exit_status(0), String::new(), stderr)),
         );
         let c = detect_compiler(creator, &f.bins[0], f.tempdir.path(), &[], &[], pool, None)
             .wait()

src/compiler/msvc.rs

@@ -29,7 +29,7 @@ use std::collections::{HashMap, HashSet};
 use std::ffi::{OsStr, OsString};
 use std::io::{self, BufWriter, Read, Write};
 use std::path::{Path, PathBuf};
-use std::process::{self, Stdio};
+use std::process;
 
 use crate::errors::*;
 
@@ -201,13 +201,9 @@ where
     if is_clang {
         cmd.arg("--driver-mode=cl");
     }
-    cmd.args(&["-nologo", "-showIncludes", "-c", "-Fonul", "-I."])
+    cmd.args(&["-nologo", "-showIncludes", "-c", "-Fonul", "-I.", "-E"])
         .arg(&input)
-        .current_dir(tempdir.path())
-        // The MSDN docs say the -showIncludes output goes to stderr,
-        // but that's not true unless running with -E.
-        .stdout(Stdio::piped())
-        .stderr(Stdio::null());
+        .current_dir(tempdir.path());
     for (k, v) in env {
         cmd.env(k, v);
     }
@@ -216,16 +212,20 @@ where
     let output = run_input_output(cmd, None).await?;
 
     if !output.status.success() {
-        bail!("Failed to detect showIncludes prefix")
+        warn!(
+            "Failed to detect showIncludes prefix (status: {:?})",
+            output.status.code().unwrap_or(-1)
+        );
     }
 
     let process::Output {
-        stdout: stdout_bytes,
+        stderr: stderr_bytes,
         ..
     } = output;
-    let stdout = from_local_codepage(&stdout_bytes)
-        .context("Failed to convert compiler stdout while detecting showIncludes prefix")?;
-    for line in stdout.lines() {
+    let preprocessor_output = from_local_codepage(&stderr_bytes)
+        .context("Failed to convert compiler stderr while detecting showIncludes prefix")?;
+
+    for line in preprocessor_output.lines() {
         if !line.ends_with("test.h") {
             continue;
         }
@@ -246,7 +246,7 @@ where
 
     debug!(
         "failed to detect showIncludes prefix with output: {}",
-        stdout
+        preprocessor_output
     );
 
     bail!("Failed to detect showIncludes prefix")
@@ -1416,8 +1416,8 @@ mod test {
         if s.starts_with("\\\\?\\") {
             s = &s[4..];
         }
-        let stdout = format!("blah: {}\r\n", s);
-        let stderr = String::from("some\r\nstderr\r\n");
+        let stderr = format!("blah: {}\r\n", s);
+        let stdout = String::from("some\r\nstdout\r\n");
         next_command(&creator, Ok(MockChild::new(exit_status(0), stdout, stderr)));
         assert_eq!(
             "blah: ",

tests/msvc-msbuild/.gitignore

@@ -0,0 +1,4 @@
+*
+!.gitignore
+!*.vcxproj
+!*.cpp

tests/msvc-msbuild/MsbuildCpp.vcxproj

@@ -0,0 +1,54 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>17.0</VCProjectVersion>
+    <Keyword>Win32Proj</Keyword>
+    <ProjectGuid>{0e44c32e-bffa-4f4b-aac8-5db71447ce37}</ProjectGuid>
+    <RootNamespace>MsbuildCpp</RootNamespace>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+    <!-- Based on https://medium.com/@parakram.majumdar/ccache-with-msbuild-devenv-f286778e0be7 -->
+    <TrackFileAccess>false</TrackFileAccess>
+    <UseMultiToolTask>true</UseMultiToolTask>
+    <CLToolExe>$(SolutionDir)/compiler/cl.exe</CLToolExe>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'" Label="Configuration">
+    <ConfigurationType>StaticLibrary</ConfigurationType>
+    <UseDebugLibraries>false</UseDebugLibraries>
+    <PlatformToolset>v143</PlatformToolset>
+  </PropertyGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <Import Project="$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props" Condition="exists('$(UserRootDir)\Microsoft.Cpp.$(Platform).user.props')" Label="LocalAppDataPlatform" />
+  </ImportGroup>
+  <PropertyGroup Label="UserMacros" />
+  <ItemDefinitionGroup Condition="'$(Configuration)|$(Platform)'=='Release|x64'">
+    <ClCompile>
+      <!-- Also mandatory: only /Z7 mode is supported -->
+      <DebugInformationFormat>OldStyle</DebugInformationFormat>
+    </ClCompile>
+    <Link>
+      <SubSystem>
+      </SubSystem>
+      <GenerateDebugInformation>true</GenerateDebugInformation>
+    </Link>
+  </ItemDefinitionGroup>
+  <ItemGroup>
+    <ClCompile Include="test_foo.cpp" />
+    <ClCompile Include="test_bar.cpp" />
+    <ClCompile Include="test_baz.cpp" />
+  </ItemGroup>
+  <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>

tests/msvc-msbuild/test_bar.cpp

@@ -0,0 +1 @@
+int bar(int x) { return x; }

tests/msvc-msbuild/test_baz.cpp

@@ -0,0 +1 @@
+int baz(int x) { return x; }

tests/msvc-msbuild/test_foo.cpp

@@ -0,0 +1 @@
+int foo(int x) { return x; }