driver: Introduce pgmcxx

Here we introduce proper support for compilation of C++ objects. This
includes:

 * logic in `configure` to detect the C++ toolchain and propagating this
   information into the `settings` file
 * logic in the driver to use the C++ toolchain when compiling C++
   sources

5 files changed, 6 insertions, 0 deletions

diff --git a/hadrian/bindist/Makefile b/hadrian/bindist/Makefile
index dbed7a0502..6b2e1f8754 100644
--- a/hadrian/bindist/Makefile
+++ b/hadrian/bindist/Makefile
@@ -105,6 +105,7 @@ lib/settings :
 	@echo '[("GCC extra via C opts", "$(GccExtraViaCOpts)")' >> $@
 	@echo ',("C compiler command", "$(SettingsCCompilerCommand)")' >> $@
 	@echo ',("C compiler flags", "$(SettingsCCompilerFlags)")' >> $@
+	@echo ',("C++ compiler command", "$(SettingsCxxCompilerCommand)")' >> $@
 	@echo ',("C++ compiler flags", "$(SettingsCxxCompilerFlags)")' >> $@
 	@echo ',("C compiler link flags", "$(SettingsCCompilerLinkFlags)")' >> $@
 	@echo ',("C compiler supports -no-pie", "$(SettingsCCompilerSupportsNoPie)")' >> $@
diff --git a/hadrian/cfg/system.config.in b/hadrian/cfg/system.config.in
index ae70823202..385279a435 100644
--- a/hadrian/cfg/system.config.in
+++ b/hadrian/cfg/system.config.in
@@ -142,6 +142,7 @@ ld-is-gnu-ld = @LdIsGNULd@
 ar-args = @ArArgs@
 
 settings-c-compiler-command = @SettingsCCompilerCommand@
+settings-cxx-compiler-command = @SettingsCxxCompilerCommand@
 settings-haskell-cpp-command = @SettingsHaskellCPPCommand@
 settings-haskell-cpp-flags = @SettingsHaskellCPPFlags@
 settings-c-compiler-flags = @SettingsCCompilerFlags@
diff --git a/hadrian/doc/user-settings.md b/hadrian/doc/user-settings.md
index 82f9964ac6..7b304ec0f3 100644
--- a/hadrian/doc/user-settings.md
+++ b/hadrian/doc/user-settings.md
@@ -369,6 +369,7 @@ the right names for them:
 	    argument for `hadrian/ghci` to work
 
   * `cc` refers to C compiler commands
+  * `cxx` refers to C++ compiler commands
 
     * `c.opts` for commands that call the C compiler on some C files
 	  * `deps.opts` for commands that call the C compiler for figuring out
diff --git a/hadrian/src/Oracles/Setting.hs b/hadrian/src/Oracles/Setting.hs
index 6ce01327c5..62a1ebcd67 100644
--- a/hadrian/src/Oracles/Setting.hs
+++ b/hadrian/src/Oracles/Setting.hs
@@ -106,6 +106,7 @@ data SettingList = ConfCcArgs Stage
 -- Eventually much of that local can probably be computed just in Hadrian.
 data SettingsFileSetting
     = SettingsFileSetting_CCompilerCommand
+    | SettingsFileSetting_CxxCompilerCommand
     | SettingsFileSetting_HaskellCPPCommand
     | SettingsFileSetting_HaskellCPPFlags
     | SettingsFileSetting_CCompilerFlags
@@ -198,6 +199,7 @@ settingList key = fmap words $ lookupSystemConfig $ case key of
 settingsFileSetting :: SettingsFileSetting -> Action String
 settingsFileSetting key = lookupSystemConfig $ case key of
     SettingsFileSetting_CCompilerCommand -> "settings-c-compiler-command"
+    SettingsFileSetting_CxxCompilerCommand -> "settings-cxx-compiler-command"
     SettingsFileSetting_HaskellCPPCommand -> "settings-haskell-cpp-command"
     SettingsFileSetting_HaskellCPPFlags -> "settings-haskell-cpp-flags"
     SettingsFileSetting_CCompilerFlags -> "settings-c-compiler-flags"
diff --git a/hadrian/src/Rules/Generate.hs b/hadrian/src/Rules/Generate.hs
index 5653bd1d25..1cd95d7961 100644
--- a/hadrian/src/Rules/Generate.hs
+++ b/hadrian/src/Rules/Generate.hs
@@ -298,6 +298,7 @@ generateSettings = do
         [ ("GCC extra via C opts", expr $ lookupSystemConfig "gcc-extra-via-c-opts")
         , ("C compiler command", expr $ settingsFileSetting SettingsFileSetting_CCompilerCommand)
         , ("C compiler flags", expr $ settingsFileSetting SettingsFileSetting_CCompilerFlags)
+        , ("C++ compiler command", expr $ settingsFileSetting SettingsFileSetting_CxxCompilerCommand)
         , ("C++ compiler flags", expr $ settingsFileSetting SettingsFileSetting_CxxCompilerFlags)
         , ("C compiler link flags", expr $ settingsFileSetting SettingsFileSetting_CCompilerLinkFlags)
         , ("C compiler supports -no-pie", expr $ settingsFileSetting SettingsFileSetting_CCompilerSupportsNoPie)