From: Anders Björklund <anders.f.bjorklund@gmail.com>
Date: Sun, 28 Apr 2019 20:50:03 +0000 (+0200)
Subject: Support using -MF /dev/null argument (#398)
X-Git-Tag: v3.7.1~11
X-Git-Url: http://git.ipfire.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=221ca4b38900055d2c89ab6bf4dc0ea388b56e50;p=thirdparty%2Fccache.git

Support using -MF /dev/null argument (#398)

This is sometimes used when detecting capabilities.
---

diff --git a/src/ccache.c b/src/ccache.c
index cb8b3a721..4b1aed0e9 100644
--- a/src/ccache.c
+++ b/src/ccache.c
@@ -1519,7 +1519,10 @@ to_cache(struct args *args, struct hash *depend_mode_hash)
 		update_cached_result_globals(object_hash);
 	}
 
-	if (generating_dependencies) {
+	bool produce_dep_file = generating_dependencies &&
+	                        !str_eq(output_dep, "/dev/null");
+
+	if (produce_dep_file) {
 		use_relative_paths_in_depfile(output_dep);
 	}
 
@@ -1555,7 +1558,7 @@ to_cache(struct args *args, struct hash *depend_mode_hash)
 	MTR_BEGIN("file", "file_put");
 
 	copy_file_to_cache(output_obj, cached_obj);
-	if (generating_dependencies) {
+	if (produce_dep_file) {
 		copy_file_to_cache(output_dep, cached_dep);
 	}
 	if (generating_coverage) {
@@ -2220,7 +2223,10 @@ calculate_object_hash(struct args *args, struct hash *hash, int direct_mode)
 			args_pop(args, 1);
 		}
 		if (generating_dependencies) {
-			cc_log("Preprocessor created %s", output_dep);
+			// Nothing is actually created with -MF /dev/null
+			if (!str_eq(output_dep, "/dev/null")) {
+				cc_log("Preprocessor created %s", output_dep);
+			}
 		}
 	}
 
@@ -2268,7 +2274,8 @@ from_cache(enum fromcache_call_mode mode, bool put_object_in_manifest)
 
 	// (If mode != FROMCACHE_DIRECT_MODE, the dependency file is created by gcc.)
 	bool produce_dep_file =
-		generating_dependencies && mode == FROMCACHE_DIRECT_MODE;
+		generating_dependencies && mode == FROMCACHE_DIRECT_MODE &&
+		!str_eq(output_dep, "/dev/null");
 
 	MTR_BEGIN("file", "file_get");
 
@@ -3837,7 +3844,8 @@ ccache(int argc, char *argv[])
 	MTR_END("main", "process_args");
 
 	if (conf->depend_mode
-	    && (!generating_dependencies || !conf->run_second_cpp || conf->unify)) {
+	    && (!generating_dependencies || str_eq(output_dep, "/dev/null") ||
+	        !conf->run_second_cpp || conf->unify)) {
 		cc_log("Disabling depend mode");
 		conf->depend_mode = false;
 	}
diff --git a/test/suites/depend.bash b/test/suites/depend.bash
index 3d2f2adc1..a13f84260 100644
--- a/test/suites/depend.bash
+++ b/test/suites/depend.bash
@@ -108,6 +108,21 @@ SUITE_depend() {
     expect_stat 'cache miss' 1
     expect_stat 'files in cache' 3
 
+    # -------------------------------------------------------------------------
+    TEST "No dependency file"
+
+    CCACHE_DEPEND=1 $CCACHE_COMPILE -MP -MMD -MF /dev/null -c test.c
+    expect_stat 'cache hit (direct)' 0
+    expect_stat 'cache hit (preprocessed)' 0
+    expect_stat 'cache miss' 1
+    expect_stat 'files in cache' 2 # .o + .manifest
+
+    CCACHE_DEPEND=1 $CCACHE_COMPILE -MP -MMD -MF /dev/null -c test.c
+    expect_stat 'cache hit (direct)' 1
+    expect_stat 'cache hit (preprocessed)' 0
+    expect_stat 'cache miss' 1
+    expect_stat 'files in cache' 2
+
     # -------------------------------------------------------------------------
     TEST "No explicit dependency file"
 
diff --git a/test/suites/direct.bash b/test/suites/direct.bash
index 643471c18..f721e7589 100644
--- a/test/suites/direct.bash
+++ b/test/suites/direct.bash
@@ -438,6 +438,21 @@ EOF
 
     rm -f third_name.d
 
+    # -------------------------------------------------------------------------
+    TEST "MF /dev/null"
+
+    $CCACHE_COMPILE -c -MD -MF /dev/null test.c
+    expect_stat 'cache hit (direct)' 0
+    expect_stat 'cache hit (preprocessed)' 0
+    expect_stat 'cache miss' 1
+    expect_stat 'files in cache' 2 # .o + .manifest
+
+    $CCACHE_COMPILE -c -MD -MF /dev/null test.c
+    expect_stat 'cache hit (direct)' 1
+    expect_stat 'cache hit (preprocessed)' 0
+    expect_stat 'cache miss' 1
+    expect_stat 'files in cache' 2
+
     # -------------------------------------------------------------------------
     TEST "Missing .d file"