feat: Improve handling of -frandom-seed and description of sloppiness

I should not be necessary to distinguish between existence and
non-existence of -frandom-seed if random_seed sloppiness is requested,
so don't hash the "-frandom-seed=" part either.

3 files changed, 5 insertions, 7 deletions

diff --git a/doc/MANUAL.adoc b/doc/MANUAL.adoc
index d979818e..fd67d169 100644
--- a/doc/MANUAL.adoc
+++ b/doc/MANUAL.adoc
@@ -1003,8 +1003,9 @@ preprocessing first.
     Ignore `+__DATE__+`, `+__TIME__+` and `+__TIMESTAMP__+` being present in the
     source code.
 *random_seed*::
-    By default, ccache will respect argument changes with `-frandom-seed`. This
-    sloppiness will allow cache hits even if the seed value is different.
+    Ignore the `-frandom-seed` option and its arguments when computing the input
+    hash. This is useful if your build system generates different seeds between
+    builds and you are OK with reusing cached results.
 --
 +
 See the discussion under _<<Troubleshooting>>_ for more information.
diff --git a/src/ccache.cpp b/src/ccache.cpp
index 29e90de7..b065f829 100644
--- a/src/ccache.cpp
+++ b/src/ccache.cpp
@@ -1555,12 +1555,9 @@ hash_argument(const Context& ctx,
     return {};
   }
 
-  // If we treat random_seed sloppily we ignore the argument when
-  // hashing.
   if (util::starts_with(args[i], "-frandom-seed=")
       && ctx.config.sloppiness().is_enabled(core::Sloppy::random_seed)) {
-    hash.hash_delimiter("arg");
-    hash.hash("-frandom-seed=");
+    LOG("Ignoring {} since random_seed sloppiness is requested", args[i]);
     return {};
   }
 
diff --git a/src/core/Sloppiness.hpp b/src/core/Sloppiness.hpp
index a7aa08ee..ef45907d 100644
--- a/src/core/Sloppiness.hpp
+++ b/src/core/Sloppiness.hpp
@@ -49,7 +49,7 @@ enum class Sloppy : uint32_t {
   ivfsoverlay = 1U << 10,
   // Allow us to include incorrect working directory in .gcno files.
   gcno_cwd = 1U << 11,
-  // Ignore changes in -frandom-seed
+  // Ignore -frandom-seed=*string*.
   random_seed = 1U << 12,
 };