Turn the coverage analysis stdenv adapters into setup hooks

Stdenv adapters are kinda weird and un-idiomatic (especially when they
don't actually change stdenv).  It's more idiomatic to say

  buildInputs = [ makeCoverageAnalysisReport ];

pkgs/build-support/release/default.nix

@@ -27,7 +27,7 @@ rec {
     } // args);
 
   coverageAnalysis = args: nixBuild (
-    { inherit lcov;
+    { inherit lcov enableCoverageInstrumentation makeCoverageAnalysisReport;
       doCoverageAnalysis = true;
     } // args);
 

pkgs/build-support/release/nix-build.nix

@@ -15,6 +15,7 @@
 , failureHook ? null
 , prePhases ? []
 , postPhases ? []
+, buildInputs ? []
 , ... } @ args:
 
 stdenv.mkDerivation (
@@ -61,13 +62,6 @@ stdenv.mkDerivation (
       . ${./functions.sh}
       origSrc=$src
       src=$(findTarballs $src | head -1)
-
-      # Set GCC flags for coverage analysis, if desired.
-      if test -n "${toString doCoverageAnalysis}"; then
-          export NIX_CFLAGS_COMPILE="-O0 --coverage $NIX_CFLAGS_COMPILE"
-          export CFLAGS="-O0"
-          export CXXFLAGS="-O0"
-      fi
     '';
 
     initPhase = ''
@@ -85,30 +79,13 @@ stdenv.mkDerivation (
 
     prePhases = ["initPhase"] ++ prePhases;
 
-    # In the report phase, create a coverage analysis report.
-    coverageReportPhase = if doCoverageAnalysis then ''
-      ${args.lcov}/bin/lcov --directory . --capture --output-file app.info
-      set -o noglob
-      ${args.lcov}/bin/lcov --remove app.info $lcovFilter > app2.info
-      set +o noglob
-      mv app2.info app.info
-
-      mkdir $out/coverage
-      ${args.lcov}/bin/genhtml app.info $lcovExtraTraceFiles -o $out/coverage > log
-
-      # Grab the overall coverage percentage for use in release overviews.
-      grep "Overall coverage rate" log | sed 's/^.*(\(.*\)%).*$/\1/' > $out/nix-support/coverage-rate
-
-      echo "report coverage $out/coverage" >> $out/nix-support/hydra-build-products
-    '' else "";
-
+    buildInputs = buildInputs ++ [ args.makeCoverageAnalysisReport ];
 
     lcovFilter = ["/nix/store/*"] ++ lcovFilter;
 
     inherit lcovExtraTraceFiles;
 
-    postPhases = postPhases ++
-      (stdenv.lib.optional doCoverageAnalysis "coverageReportPhase") ++ ["finalPhase"];
+    postPhases = postPhases ++ ["finalPhase"];
 
     meta = (if args ? meta then args.meta else {}) // {
       description = if doCoverageAnalysis then "Coverage analysis" else "Nix package for ${stdenv.system}";

pkgs/build-support/setup-hooks/enable-coverage-instrumentation.sh

@@ -0,0 +1,14 @@
+# Force GCC to build with coverage instrumentation.  Also disable
+# optimisation, since it may confuse things.
+export NIX_CFLAGS_COMPILE="$NIX_CFLAGS_COMPILE -O0 --coverage"
+
+# FIXME: Handle the case where postUnpack is already set.
+postUnpack() {
+    # This is an uberhack to prevent libtool from remoaving gcno
+    # files.  This has been fixed in libtool, but there are packages
+    # out there with old ltmain.sh scripts.  See
+    # http://www.mail-archive.com/libtool@gnu.org/msg10725.html
+    for i in $(find -name ltmain.sh); do
+        substituteInPlace $i --replace '*.$objext)' '*.$objext | *.gcno)'
+    done
+}

pkgs/build-support/setup-hooks/make-coverage-analysis-report.sh

@@ -0,0 +1,18 @@
+postPhases+=" coverageReportPhase"
+
+coverageReportPhase() {
+    lcov --directory . --capture --output-file app.info
+    set -o noglob
+    lcov --remove app.info $lcovFilter > app2.info
+    set +o noglob
+    mv app2.info app.info
+
+    mkdir -p $out/coverage
+    genhtml app.info $lcovExtraTraceFiles -o $out/coverage > log
+
+    # Grab the overall coverage percentage for use in release overviews.
+    mkdir -p $out/nix-support
+    grep "Overall coverage rate" log | sed 's/^.*(\(.*\)%).*$/\1/' > $out/nix-support/coverage-rate
+
+    echo "report coverage $out/coverage" >> $out/nix-support/hydra-build-products
+}

pkgs/stdenv/adapters.nix

@@ -231,29 +231,7 @@ rec {
      programs like lcov to produce pretty-printed reports.
   */
   addCoverageInstrumentation = stdenv:
-    # Object files instrumented with coverage analysis write runtime
-    # coverage data to <path>/<object>.gcda, where <path> is the
-    # location where gcc originally created the object file.  That
-    # would be /tmp/nix-build-<something>, which will be long gone by
-    # the time we run the program.  Furthermore, the <object>.gcno
-    # files created at compile time are also written there.  And to
-    # make nice coverage reports with lcov, we need the source code.
-    # So we have to use the `keepBuildTree' adapter as well.
-    let stdenv' = cleanupBuildTree (keepBuildTree stdenv); in
-    { mkDerivation = args: stdenv'.mkDerivation (args // {
-        NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " -O0 --coverage";
-        postUnpack =
-          ''
-            # This is an uberhack to prevent libtool from removing gcno
-            # files.  This has been fixed in libtool, but there are
-            # packages out there with old ltmain.sh scripts.
-            # See http://www.mail-archive.com/libtool@gnu.org/msg10725.html
-            for i in $(find -name ltmain.sh); do
-                substituteInPlace $i --replace '*.$objext)' '*.$objext | *.gcno)'
-            done
-          '' + args.postUnpack or "";
-      });
-    };
+    cleanupBuildTree (keepBuildTree (overrideInStdenv stdenv [ pkgs.enableCoverageInstrumentation ]));
 
 
   /* Replace the meta.maintainers field of a derivation.  This is useful

pkgs/stdenv/generic/default.nix

@@ -87,10 +87,10 @@ let
               userHook = config.stdenv.userHook or null;
 
               # Inputs built by the cross compiler.
-              buildInputs = lib.optionals (crossConfig != null) buildInputs ++ extraBuildInputs;
+              buildInputs = lib.optionals (crossConfig != null) (buildInputs ++ extraBuildInputs);
               propagatedBuildInputs = lib.optionals (crossConfig != null) propagatedBuildInputs;
               # Inputs built by the usual native compiler.
-              nativeBuildInputs = nativeBuildInputs ++ lib.optionals (crossConfig == null) buildInputs;
+              nativeBuildInputs = nativeBuildInputs ++ lib.optionals (crossConfig == null) (buildInputs ++ extraBuildInputs);
               propagatedNativeBuildInputs = propagatedNativeBuildInputs ++
                 lib.optionals (crossConfig == null) propagatedBuildInputs;
           }))) (

pkgs/top-level/all-packages.nix

@@ -396,6 +396,12 @@ let
 
   fixDarwinDylibNames = makeSetupHook { } ../build-support/setup-hooks/fix-darwin-dylib-names.sh;
 
+  enableCoverageInstrumentation = makeSetupHook { } ../build-support/setup-hooks/enable-coverage-instrumentation.sh;
+
+  makeCoverageAnalysisReport = makeSetupHook
+    { deps = [ pkgs.lcov pkgs.enableCoverageInstrumentation ]; }
+    ../build-support/setup-hooks/make-coverage-analysis-report.sh;
+
 
   ### TOOLS