Use .dsl.cpp suffix for DSL C++ instead of _dsl.cpp.

This requires the GN processing to be slightly more complex, as GN has
no native support for more than one extension on a file.
Context: https://groups.google.com/a/chromium.org/g/gn-dev/c/RdEpjeYtb-4

Change-Id: I630511fca9eb291f0e414481ef439f18a8e1b72f
Bug: skia:11854
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/396197
Reviewed-by: Ethan Nicholas <ethannicholas@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>

BUILD.gn

@@ -780,8 +780,15 @@ if (skia_compile_sksl_tests) {
         src = resourcesDir + partialPath
 
         dir = get_path_info(dst, "dir")
-        name = get_path_info(dst, "name")
-        ext = get_path_info(dst, "extension")
+
+        # We want to support double-extensions (for '.dsl.cpp') but GN doesn't natively handle this.
+        # Workaround: http://go/ggroup/a/chromium.org/g/gn-dev/c/RdEpjeYtb-4
+        # For input path "file.aa.bb", name will contain "file" and ext will contain ".aa.bb".
+        # For input path "file.cc", name will contain "file" and ext will contain ".cc".
+        nameTmp = get_path_info(dst, "name")
+        name = get_path_info(nameTmp, "name")
+        ext = get_path_info(nameTmp, "extension")
+        ext += get_path_info(dst, "extension")
         response_file_contents += rebase_path([
                                                 src,
                                                 dir,
@@ -814,7 +821,7 @@ if (skia_compile_sksl_tests) {
   compile_sksl("dsl_fp_tests") {
     sources = sksl_dsl_fp_tests_sources
     outExtensions = [
-      "_dsl.cpp",
+      ".dsl.cpp",
       ".h",
     ]
     lang = "--dslfp"

gn/compile_sksl_tests.py

@@ -82,7 +82,7 @@ for input, targetDir in pairwise(inputs):
         worklist.write(settings + "\n\n")
     elif lang == "--dslfp":
         worklist.write(input + "\n")
-        worklist.write(target + "_dsl.cpp\n")
+        worklist.write(target + ".dsl.cpp\n")
         worklist.write(settings + "\n\n")
         worklist.write(input + "\n")
         worklist.write(target + ".h\n")
@@ -127,7 +127,7 @@ else:
 # `### Compilation failed`, its sibling should be replaced by an empty file. This improves clarity
 # during code review; a failure on either file means that success on the sibling is irrelevant.
 if lang == "--fp" or lang == "--dslfp":
-    cppExtension = ("_dsl.cpp" if lang == "--dslfp" else ".cpp")
+    cppExtension = (".dsl.cpp" if lang == "--dslfp" else ".cpp")
     hExtension = ".h"
 
     for target in targets:

gn/sksl_tests.gni

@@ -592,7 +592,7 @@ sksl_rte_error_tests = [
 sksl_fp_tests_sources = sksl_fp_error_tests + sksl_fp_tests
 
 # Tests in sksl_dsl_fp_tests_sources will be compiled with --settings on, and are expected to
-# generate a _dsl.cpp and a .h output file.
+# generate a .dsl.cpp and a .h output file.
 sksl_dsl_fp_tests_sources = sksl_dsl_fp_tests
 
 # Tests in sksl_glsl_tests_sources will be compiled with --settings on, and are expected to generate

src/sksl/SkSLMain.cpp

@@ -379,7 +379,7 @@ ResultCode processCommand(std::vector<SkSL::String>& args) {
                 [&](SkSL::Compiler& compiler, SkSL::Program& program, SkSL::OutputStream& out) {
                     return compiler.toH(program, base_name(inputPath.c_str(), "Gr", ".fp"), out);
                 });
-    } else if (outputPath.endsWith("_dsl.cpp")) {
+    } else if (outputPath.endsWith(".dsl.cpp")) {
         settings.fReplaceSettings = false;
         settings.fPermitInvalidStaticTests = true;
         return compileProgram(