Allow clang to write compilation database records.

When integrating compilation database output into existing build
systems, two approaches dominate so far. Ad-hoc implementation of the
JSON output rules or using compiler wrappers. This patch adds a new
option "-MJ foo.json" which gives a slightly cleaned up compilation
record. The output is a fragment, i.e. you still need to add the array
markers, but it allows multiple files to be easy merged.

This way the only change in a build system is adding the option with
potentially a per-target output file and merging the files with
something like
  (echo '['; cat *.o.json; echo ']' > compilation_database.json
or some additional filtering to remove the trailing comma for strict
JSON compliance.

Differential Revision: https://reviews.llvm.org/D27140

llvm-svn: 288821

1 files changed, 10 insertions, 0 deletions

diff --git a/clang/test/Driver/compilation_database.c b/clang/test/Driver/compilation_database.c
new file mode 100644
index 00000000000..bb6c9c7599e
--- /dev/null
+++ b/clang/test/Driver/compilation_database.c
@@ -0,0 +1,10 @@
+// RUN: %clang -MD -MP -c -x c %s -xc++ %s -Wall -MJ - 2>&1 | FileCheck %s
+// RUN: not %clang -c -x c %s -MJ %s/non-existant 2>&1 | FileCheck --check-prefix=ERROR %s
+
+// CHECK: { "directory": "[[CWD:[^"]+]]",  "file": "[[SRC:[^"]+[/|\\]compilation_database.c]]", "output": "compilation_database.o", "arguments": ["{{[^"]*}}clang{{[^"]*}}", "-xc", "[[SRC]]", "-c", "-Wall", "--target={{[^"]+}}"]},
+// CHECK: { "directory": "[[CWD:[^"]+]]",  "file": "[[SRC:[^"]+[/|\\]compilation_database.c]]", "output": "compilation_database.o", "arguments": ["{{[^"]*}}clang{{[^"]*}}", "-xc++", "[[SRC]]", "-c", "-Wall", "--target={{[^"]+}}"]},
+// ERROR: error: compilation database '{{.*}}/non-existant' could not be opened:
+
+int main(void) {
+  return 0;
+}