add coverage options to core.runtime and leave merging off by default

Author: MartinNowak

src/core/runtime.d

@@ -314,12 +314,37 @@ struct Runtime
 
 
 private:
+
     // NOTE: This field will only ever be set in a static ctor and should
     //       never occur within any but the main thread, so it is safe to
     //       make it __gshared.
     __gshared ModuleUnitTester sm_moduleUnitTester = null;
 }
 
+/**
+ * Set source file path for coverage reports.
+ *
+ * Params:
+ *  path = The new path name.
+ */
+extern (C) void dmd_coverSourcePath(string path);
+
+/**
+ * Set output path for coverage reports.
+ *
+ * Params:
+ *  path = The new path name.
+ */
+extern (C) void dmd_coverDestPath(string path);
+
+/**
+ * Enable merging of coverage reports with existing data.
+ *
+ * Params:
+ *  merge = enable/disable coverage merge mode
+ */
+extern (C) void dmd_coverSetMerge(bool flag);
+
 ///////////////////////////////////////////////////////////////////////////////
 // Overridable Callbacks
 ///////////////////////////////////////////////////////////////////////////////

src/rt/cover.d

@@ -59,7 +59,7 @@ private
         Cover[] gdata;
         string  srcpath;
         string  dstpath;
-        bool    merge = true;
+        bool    merge;
     }
 }
 

test/coverage/Makefile

@@ -10,7 +10,7 @@ LINKDL:=
 SRC:=src
 ROOT:=./obj/$(OS)/$(MODEL)
 NORMAL_TESTS:=$(addprefix $(ROOT)/,$(addsuffix .done,basic))
-MERGE_TESTS:=$(addprefix $(ROOT)/,$(addsuffix .done,merge merge_false))
+MERGE_TESTS:=$(addprefix $(ROOT)/,$(addsuffix .done,merge merge_true))
 
 DIFF:=diff
 

test/coverage/src-merge.lst.exp

@@ -1,5 +1,5 @@
        |int main()
        |{
-      2|    return 0;
+      1|    return 0;
        |}
 src/merge.d is 100% covered

test/coverage/src-merge_false.lst.exp

@@ -0,0 +1,7 @@
+       |import core.runtime;
+       |
+       |void main()
+       |{
+      2|    dmd_coverSetMerge(true);
+       |}
+src/merge_true.d is 100% covered

test/coverage/src-merge_true.lst.exp

@@ -0,0 +1,6 @@
+import core.runtime;
+
+void main()
+{
+    dmd_coverSetMerge(true);
+}