configure: build the debug and instrumented runtimes by default (#1526)

This commit builds the debug and instrumented runtimes by default.

For a user that discovers a use for either of those, not having built
by default makes the experience pretty bad: they have to recompile
their own OCaml compiler, possibly from a source checkout if the
option is not available on opam...

With this change the total compilation time only increased by
7 seconds on my machine, from 3m24s to 3m33s -- these are sequential
builds, with parallel builds the difference is lost in the noise.

We wish to make -with-instrumented-runtime the default, but not break
the build on systems that do not support it -- when clock_gettime is
missing. This is done by tracking whether -with-instrumented-runtime
was set explicitly or is the default value; in the latter case,
a missing clock_gettime defaults to no instrumented runtime, without
raising an error at configure-time.

1 files changed, 24 insertions, 10 deletions

diff --git a/configure b/configure
index ff6a39b20e..21a05e3076 100755
--- a/configure
+++ b/configure
@@ -45,8 +45,7 @@ graph_wanted=yes
 pthread_wanted=yes
 dl_defs=''
 verbose=false
-debugruntime=false
-with_instrumented_runtime=false
+debugruntime=true
 with_sharedlibs=true
 partialld="ld -r"
 with_debugger=ocamldebugger
@@ -69,6 +68,9 @@ with_cplugins=false
 with_fpic=false
 flat_float_array=true
 
+# we distinguish '' (not set) from 'true' (explicitly set by the user)
+with_instrumented_runtime=''
+
 # Try to turn internationalization off, can cause config.guess to malfunction!
 unset LANG
 unset LC_ALL LC_CTYPE LC_COLLATE LC_MESSAGES LC_MONETARY LC_NUMERIC LC_TIME
@@ -171,9 +173,13 @@ while : ; do
     -verbose|--verbose)
         verbose=true;;
     -with-debug-runtime|--with-debug-runtime)
-        debugruntime=true;;
+        debugruntime=true;; # default
+    -no-debug-runtime|--no-debug-runtime)
+        debugruntime=false;;
     -with-instrumented-runtime|--with-instrumented-runtime)
         with_instrumented_runtime=true;;
+    -no-instrumented-runtime|--no-instrumented-runtime)
+        with_instrumented_runtime=false;;
     -no-debugger|--no-debugger)
         with_debugger="";;
     -no-ocamldoc|--no-ocamldoc)
@@ -1190,20 +1196,28 @@ fi
 
 # For instrumented runtime
 # (clock_gettime needs -lrt for glibc before 2.17)
-if $with_instrumented_runtime; then
-  with_instrumented_runtime=false #enabled it only if found
+if test "$with_instrumented_runtime" != "false"; then
+  instrumented_runtime_support="nonsupported"
   for libs in "" "-lrt"; do
     if sh ./hasgot $libs clock_gettime; then
       inf "clock_gettime functions found (with libraries '$libs')"
       instrumented_runtime_libs="${libs}"
-      with_instrumented_runtime=true;
+      instrumented_runtime_support="supported";
       break
     fi
   done
-  if ! $with_instrumented_runtime; then
-      err "clock_gettime functions not found. " \
-          "Instrumented runtime can't be built."
-  fi
+  case "$with_instrumented_runtime,$instrumented_runtime_support" in
+    *,supported)
+        with_instrumented_runtime=true;;
+    true,nonsupported)
+        with_instrumented_runtime=false;
+        err "clock_gettime functions not found. " \
+            "Instrumented runtime can't be built.";;
+    ,nonsupported)
+        with_instrumented_runtime=false;
+        inf "clock_gettime functions not found. " \
+            "Instrumented runtime can't be built.";;
+  esac
 fi
 
 # Configuration for the libraries