Add an option to keep native debug symbols (#39203)

When packaging .NET for Linux distributions, the package builders
generally use a different workflow for shipping symbols to users:

1. The package maintainer builds code with the debug flags (such as
   `-g`) to generate full native debug info and symbols.

2. Nothing is stripped from build by the package maintainer.

3. The build system (`rpmbuild`, `debuild`) removes the debug
   info (or debug symbols) from the code and creates separate
   `-debuginfo` or `-debug` packages that contain just the debug
   symbols.

4. These debug packages are then distributed along with the normal
   packages using the normal Linux distribution mechanisms. This lets
   users install the exact set of debug symbols matching their other
   package.

To support this workflow in dotnet/runtime, we need to add optional
support for not stripping debug symbols. I used it has follows:

    CFLAGS=-g CXXFLAGS=-g ./build.sh --keepnativesymbols true

After this build, the built binaries include all debug symbols.

I can then rely on the distro package build system to identify, strip,
package and ship the debug info/symbols separately.

See https://github.com/dotnet/runtime/issues/3781 and
https://github.com/dotnet/source-build/issues/267 for more details on
the background and motivation.

For some related fixes, see:

- https://github.com/dotnet/coreclr/pull/3445
- https://github.com/dotnet/corefx/pull/24979

7 files changed, 34 insertions, 5 deletions

diff --git a/Directory.Build.props b/Directory.Build.props
index dc11cc1b9f1..6a688d500c4 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -107,6 +107,8 @@
   <PropertyGroup>
     <!-- Default to portable build if not explicitly set -->
     <PortableBuild Condition="'$(PortableBuild)' == ''">true</PortableBuild>
+    <!-- Default to discarding symbols if not explicitly set -->
+    <KeepNativeSymbols Condition="'$(KeepNativeSymbols)' == ''">false</KeepNativeSymbols>
     <!-- Used for launchSettings.json and runtime config files. -->
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <!-- Determine what architecture we are building on. -->
diff --git a/eng/build.sh b/eng/build.sh
index f271bb0ca76..1179f8efd27 100755
--- a/eng/build.sh
+++ b/eng/build.sh
@@ -76,6 +76,7 @@ usage()
   echo "  --gcc                      Optional argument to build using gcc in PATH (default)."
   echo "  --gccx.y                   Optional argument to build using gcc version x.y."
   echo "  --portablebuild            Optional argument: set to false to force a non-portable build."
+  echo "  --keepnativesymbols        Optional argument: set to true to keep native symbols/debuginfo in generated binaries."
   echo ""
 
   echo "Command line arguments starting with '/p:' are passed through to MSBuild."
@@ -402,6 +403,18 @@ while [[ $# > 0 ]]; do
       shift 2
       ;;
 
+     -keepnativesymbols)
+      if [ -z ${2+x} ]; then
+        echo "No value for keepNativeSymbols is supplied. See help (--help) for supported values." 1>&2
+        exit 1
+      fi
+      passedKeepNativeSymbols="$(echo "$2" | awk '{print tolower($0)}')"
+      if [ "$passedKeepNativeSymbols" = true ]; then
+        arguments="$arguments /p:KeepNativeSymbols=true"
+      fi
+      shift 2
+      ;;
+
       *)
       extraargs="$extraargs $1"
       shift 1
diff --git a/eng/native/build-commons.sh b/eng/native/build-commons.sh
index 877ef003bbe..2e94d68fe69 100755
--- a/eng/native/build-commons.sh
+++ b/eng/native/build-commons.sh
@@ -225,6 +225,7 @@ usage()
     echo "-portablebuild: pass -portablebuild=false to force a non-portable build."
     echo "-skipconfigure: skip build configuration."
     echo "-skipgenerateversion: disable version generation even if MSBuild is supported."
+    echo "-keepnativesymbols: keep native/unmanaged debug symbols."
     echo "-verbose: optional argument to enable verbose build output."
     echo ""
     echo "Additional Options:"
@@ -354,6 +355,10 @@ while :; do
                 __CompilerMinorVersion="${parts[1]}"
             ;;
 
+        keepnativesymbols|-keepnativesymbols)
+            __CMakeArgs="$__CMakeArgs -DCLR_CMAKE_KEEP_NATIVE_SYMBOLS=true"
+            ;;
+
         msbuildonunsupportedplatform|-msbuildonunsupportedplatform)
             __msbuildonunsupportedplatform=1
             ;;
diff --git a/eng/native/functions.cmake b/eng/native/functions.cmake
index 525c289d988..27396aa5bb5 100644
--- a/eng/native/functions.cmake
+++ b/eng/native/functions.cmake
@@ -336,8 +336,10 @@ function(strip_symbols targetName outputFilename)
 endfunction()
 
 function(install_with_stripped_symbols targetName kind destination)
-    strip_symbols(${targetName} symbol_file)
-    install_symbols(${symbol_file} ${destination})
+    if(NOT CLR_CMAKE_KEEP_NATIVE_SYMBOLS)
+      strip_symbols(${targetName} symbol_file)
+      install_symbols(${symbol_file} ${destination})
+    endif()
     if ("${kind}" STREQUAL "TARGETS")
       set(install_source ${targetName})
     elseif("${kind}" STREQUAL "PROGRAMS")
@@ -374,13 +376,17 @@ function(install_clr)
   foreach(targetName ${INSTALL_CLR_TARGETS})
     list(FIND CLR_CROSS_COMPONENTS_LIST ${targetName} INDEX)
     if (NOT DEFINED CLR_CROSS_COMPONENTS_LIST OR NOT ${INDEX} EQUAL -1)
-        strip_symbols(${targetName} symbol_file)
+        if (NOT CLR_CMAKE_KEEP_NATIVE_SYMBOLS)
+          strip_symbols(${targetName} symbol_file)
+        endif()
 
         foreach(destination ${destinations})
           # We don't need to install the export libraries for our DLLs
           # since they won't be directly linked against.
           install(PROGRAMS $<TARGET_FILE:${targetName}> DESTINATION ${destination})
-          install_symbols(${symbol_file} ${destination})
+          if (NOT CLR_CMAKE_KEEP_NATIVE_SYMBOLS)
+            install_symbols(${symbol_file} ${destination})
+          endif()
 
           if(CLR_CMAKE_PGO_INSTRUMENT)
               if(WIN32)
diff --git a/src/coreclr/runtime.proj b/src/coreclr/runtime.proj
index 79b99c1649e..0422ba17afd 100644
--- a/src/coreclr/runtime.proj
+++ b/src/coreclr/runtime.proj
@@ -11,6 +11,7 @@
       <_CoreClrBuildArg Condition="'$(ContinuousIntegrationBuild)' == 'true'" Include="-ci" />
       <_CoreClrBuildArg Condition="'$(CrossBuild)' == 'true'" Include="-cross" />
       <_CoreClrBuildArg Condition="'$(PortableBuild)' != 'true'" Include="-portablebuild=false" />
+      <_CoreClrBuildArg Condition="'$(KeepNativeSymbols)' != 'false'" Include="-keepnativesymbols" />
       <_CoreClrBuildArg Condition="!$([MSBuild]::IsOsPlatform(Windows))" Include="-os $(TargetOS)" />
 
       <_CoreClrBuildArg Condition="$([MSBuild]::IsOsPlatform(Windows)) and
diff --git a/src/installer/corehost/corehost.proj b/src/installer/corehost/corehost.proj
index 69927e8304b..38c104ca005 100644
--- a/src/installer/corehost/corehost.proj
+++ b/src/installer/corehost/corehost.proj
@@ -30,6 +30,7 @@
       <BuildArgs>$(Configuration) $(TargetArchitecture) -apphostver "$(AppHostVersion)" -hostver "$(HostVersion)" -fxrver "$(HostResolverVersion)" -policyver "$(HostPolicyVersion)" -commithash "$(LatestCommit)" -os $(TargetOS)</BuildArgs>
       <BuildArgs>$(BuildArgs) -cmakeargs "-DVERSION_FILE_PATH=$(NativeVersionFile)"</BuildArgs>
       <BuildArgs Condition="'$(PortableBuild)' != 'true'">$(BuildArgs) -portablebuild=false</BuildArgs>
+      <BuildArgs Condition="'$(KeepNativeSymbols)' != 'false'">$(BuildArgs) -keepnativesymbols</BuildArgs>
       <BuildArgs Condition="'$(CrossBuild)' == 'true'">$(BuildArgs) -cross</BuildArgs>
       <BuildArgs Condition="'$(Compiler)' != ''">$(BuildArgs) $(Compiler)</BuildArgs>
       <BuildArgs Condition="'$(CMakeArgs)' != ''">$(BuildArgs) $(CMakeArgs)</BuildArgs>
diff --git a/src/libraries/Native/build-native.proj b/src/libraries/Native/build-native.proj
index beaf3098745..6f3d4aa0892 100644
--- a/src/libraries/Native/build-native.proj
+++ b/src/libraries/Native/build-native.proj
@@ -24,6 +24,7 @@
       <_ProcessorCountArg> -numproc $(MSBuildNodeCount)</_ProcessorCountArg>
       <_PortableBuildArg Condition="'$(PortableBuild)' != 'true'"> -portablebuild=false</_PortableBuildArg>
       <_CrossBuildArg Condition="'$(CrossBuild)' == 'true'"> -cross</_CrossBuildArg>
+      <_KeepNativeSymbolsBuildArg Condition="'$(KeepNativeSymbols)' != 'false'"> -keepnativesymbols</_KeepNativeSymbolsBuildArg>
       <_CMakeArgs Condition="'$(CMakeArgs)' != ''"> $(CMakeArgs)</_CMakeArgs>
 
       <!--
@@ -31,7 +32,7 @@
         used to force a specific compiler toolset.
       -->
       <_BuildNativeCompilerArg Condition="'$(BuildNativeCompiler)' != ''"> $(BuildNativeCompiler)</_BuildNativeCompilerArg>
-      <_BuildNativeUnixArgs>$(_BuildNativeArgs)$(_ProcessCountArg)$(_PortableBuildArg)$(_CrossBuildArg)$(_BuildNativeCompilerArg)$(_CMakeArgs) $(Compiler)</_BuildNativeUnixArgs>
+      <_BuildNativeUnixArgs>$(_BuildNativeArgs)$(_ProcessCountArg)$(_PortableBuildArg)$(_CrossBuildArg)$(_BuildNativeCompilerArg)$(_KeepNativeSymbolsBuildArg)$(_CMakeArgs) $(Compiler)</_BuildNativeUnixArgs>
     </PropertyGroup>
 
     <Message Text="$(MSBuildThisFileDirectory)build-native.sh $(_BuildNativeUnixArgs)" Importance="High"/>