From: Joel Rosdahl <joel@rosdahl.net>
Date: Thu, 24 Mar 2022 20:17:17 +0000 (+0100)
Subject: fix: Don’t cache preexisting object file when using -fsyntax-only
X-Git-Tag: v4.6.1~56
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=d4fcdcf2d5bfd3f9ec416a303016eba9e7f42f86;p=thirdparty%2Fccache.git

fix: Don’t cache preexisting object file when using -fsyntax-only

Fixes #1034.
---

diff --git a/src/ccache.cpp b/src/ccache.cpp
index a9e4b2195..a3dade4ca 100644
--- a/src/ccache.cpp
+++ b/src/ccache.cpp
@@ -1064,17 +1064,20 @@ to_cache(Context& ctx,
     Depfile::make_paths_relative_in_output_dep(ctx);
   }
 
-  const auto obj_stat = Stat::stat(ctx.args_info.output_obj);
-  if (!obj_stat) {
-    if (ctx.args_info.expect_output_obj) {
-      LOG_RAW("Compiler didn't produce an object file (unexpected)");
+  Stat obj_stat;
+  if (!ctx.args_info.expect_output_obj) {
+    // Don't probe for object file when we don't expect one since we otherwise
+    // will be fooled by an already existing object file.
+    LOG_RAW("Compiler not expected to produce an object file");
+  } else {
+    obj_stat = Stat::stat(ctx.args_info.output_obj);
+    if (!obj_stat) {
+      LOG_RAW("Compiler didn't produce an object file");
       return nonstd::make_unexpected(Statistic::compiler_produced_no_output);
-    } else {
-      LOG_RAW("Compiler didn't produce an object file (expected)");
+    } else if (obj_stat.size() == 0) {
+      LOG_RAW("Compiler produced an empty object file");
+      return nonstd::make_unexpected(Statistic::compiler_produced_empty_output);
     }
-  } else if (obj_stat.size() == 0) {
-    LOG_RAW("Compiler produced an empty object file");
-    return nonstd::make_unexpected(Statistic::compiler_produced_empty_output);
   }
 
   MTR_BEGIN("result", "result_put");
diff --git a/test/suites/base.bash b/test/suites/base.bash
index 050d8bd07..b2d914951 100644
--- a/test/suites/base.bash
+++ b/test/suites/base.bash
@@ -1097,6 +1097,42 @@ EOF
     expect_stat files_in_cache 0
     expect_stat compiler_produced_no_output 2
 
+    # -------------------------------------------------------------------------
+    TEST "-fsyntax-only"
+
+    echo existing >test1.o
+    $CCACHE_COMPILE -fsyntax-only test1.c
+    expect_stat preprocessed_cache_hit 0
+    expect_stat cache_miss 1
+    expect_stat files_in_cache 1
+    expect_content test1.o existing
+
+    rm test1.o
+
+    $CCACHE_COMPILE -fsyntax-only test1.c
+    expect_stat preprocessed_cache_hit 1
+    expect_stat cache_miss 1
+    expect_stat files_in_cache 1
+    expect_missing test1.o
+
+    # -------------------------------------------------------------------------
+    TEST "-fsyntax-only /dev/null"
+
+    echo existing >null.o
+    $CCACHE_COMPILE -fsyntax-only -x c /dev/null
+    expect_stat preprocessed_cache_hit 0
+    expect_stat cache_miss 1
+    expect_stat files_in_cache 1
+    expect_content null.o existing
+
+    rm null.o
+
+    $CCACHE_COMPILE -fsyntax-only -x c /dev/null
+    expect_stat preprocessed_cache_hit 1
+    expect_stat cache_miss 1
+    expect_stat files_in_cache 1
+    expect_missing null.o
+
     # -------------------------------------------------------------------------
     TEST "No object file due to -fsyntax-only"