Bazel: Stop leaking internal headers to other libraries (#729)

This is important for e.g. glib/gio, which also has an internal config.h, and fails to compile, as it often picks up the pcre2 config.h first.

---------

Co-authored-by: Nicholas Wilson <nicholas@nicholaswilson.me.uk>

Author: feuerste

BUILD.bazel

@@ -20,6 +20,47 @@ copy_file(
     out = "src/pcre2_chartables.c",
 )
 
+LOCAL_DEFINES = [
+    "HAVE_CONFIG_H",
+    "HAVE_MEMMOVE",
+    "HAVE_STRERROR",
+    "PCRE2_CODE_UNIT_WIDTH=8",
+    "PCRE2_STATIC",
+    "SUPPORT_PCRE2_8",
+    "SUPPORT_UNICODE",
+] + select({
+    "@platforms//os:windows": [],
+    "//conditions:default": ["HAVE_UNISTD_H"],
+})
+
+# Workaround for a Bazel quirk. It is extremely strict about the #include path
+# used for internal headers. We have our headers inside src/, but we #include
+# them as '#include "pcre2_internal.h"', assuming that src/ is added to the
+# compiler's include path. Unfortunately, that violates the conventions used by
+# Bazel.
+#
+# This is a workaround. Note that we can't use the "include = [...]" property
+# to add the src/ directory, since that pollutes the include path for projects
+# depending on PCRE2 (we must not make our config.h file visible to consumers
+# of PCRE2).
+cc_library(
+    name = "pcre2_internal_headers",
+    hdrs = [
+        "src/pcre2_compile.h",
+        "src/pcre2_internal.h",
+        "src/pcre2_intmodedep.h",
+        "src/pcre2_jit_match_inc.h",
+        "src/pcre2_jit_misc_inc.h",
+        "src/pcre2_printint_inc.h",
+        "src/pcre2_ucp.h",
+        "src/pcre2_ucptables_inc.h",
+        "src/pcre2_util.h",
+        ":config_h_generic",
+    ],
+    strip_include_prefix = "src",
+    visibility = ["//visibility:private"],
+)
+
 cc_library(
     name = "pcre2",
     srcs = [
@@ -36,15 +77,12 @@ cc_library(
         "src/pcre2_extuni.c",
         "src/pcre2_find_bracket.c",
         "src/pcre2_jit_compile.c",
-        "src/pcre2_jit_match_inc.h",
-        "src/pcre2_jit_misc_inc.h",
         "src/pcre2_maketables.c",
         "src/pcre2_match.c",
         "src/pcre2_match_data.c",
         "src/pcre2_newline.c",
         "src/pcre2_ord2utf.c",
         "src/pcre2_pattern_info.c",
-        "src/pcre2_printint_inc.h",
         "src/pcre2_script_run.c",
         "src/pcre2_serialize.c",
         "src/pcre2_string_utils.c",
@@ -56,48 +94,20 @@ cc_library(
         "src/pcre2_valid_utf.c",
         "src/pcre2_xclass.c",
         ":pcre2_chartables_c",
-        "src/pcre2_compile.h",
-        "src/pcre2_internal.h",
-        "src/pcre2_intmodedep.h",
-        "src/pcre2_ucp.h",
-        "src/pcre2_ucptables_inc.h",
-        "src/pcre2_util.h",
-        ":config_h_generic",
-    ],
-    textual_hdrs = [
     ],
-    hdrs = [
-        ":pcre2_h_generic",
-    ],
-    local_defines = [
-        "HAVE_CONFIG_H",
-        "HAVE_MEMMOVE",
-        "PCRE2_CODE_UNIT_WIDTH=8",
-        "PCRE2_STATIC",
-        "SUPPORT_UNICODE",
-    ],
-    includes = ["src"],
+    hdrs = [":pcre2_h_generic"],
+    implementation_deps = [":pcre2_internal_headers"],
+    local_defines = LOCAL_DEFINES,
     strip_include_prefix = "src",
     visibility = ["//visibility:public"],
 )
 
 cc_library(
     name = "pcre2-posix",
-    srcs = [
-        "src/pcre2posix.c",
-        ":config_h_generic",
-    ],
-    hdrs = [
-        "src/pcre2posix.h",
-    ],
-    local_defines = [
-        "HAVE_CONFIG_H",
-        "HAVE_MEMMOVE",
-        "PCRE2_CODE_UNIT_WIDTH=8",
-        "PCRE2_STATIC",
-        "SUPPORT_UNICODE",
-    ],
-    includes = ["src"],
+    srcs = ["src/pcre2posix.c"],
+    hdrs = ["src/pcre2posix.h"],
+    implementation_deps = [":pcre2_internal_headers"],
+    local_defines = LOCAL_DEFINES,
     strip_include_prefix = "src",
     visibility = ["//visibility:public"],
     deps = [":pcre2"],
@@ -127,27 +137,19 @@ cc_library(
 
 cc_binary(
     name = "pcre2test",
-    srcs = [
-        "src/pcre2test.c",
-        ":config_h_generic",
-    ],
-    local_defines = [
-        "HAVE_CONFIG_H",
-        "HAVE_MEMMOVE",
-        "HAVE_STRERROR",
-        "PCRE2_STATIC",
-        "SUPPORT_UNICODE",
-        "SUPPORT_PCRE2_8",
-    ] + select({
-        "@platforms//os:windows": [],
-        "//conditions:default": ["HAVE_UNISTD_H"],
-    }),
+    srcs = ["src/pcre2test.c"],
     linkopts = select({
         "@platforms//os:windows": ["-STACK:2500000"],
         "//conditions:default": [],
     }),
+    local_defines = LOCAL_DEFINES,
     visibility = ["//visibility:public"],
-    deps = [":pcre2test_dotc_headers", ":pcre2", ":pcre2-posix"],
+    deps = [
+        ":pcre2",
+        ":pcre2-posix",
+        ":pcre2_internal_headers",
+        ":pcre2test_dotc_headers",
+    ],
 )
 
 filegroup(
@@ -157,6 +159,7 @@ filegroup(
 
 native_test(
     name = "pcre2_test",
+    size = "small",
     src = select({
         "@platforms//os:windows": "RunTest.bat",
         "//conditions:default": "RunTest",
@@ -165,6 +168,8 @@ native_test(
         "@platforms//os:windows": "RunTest.bat",
         "//conditions:default": "RunTest",
     }),
-    data = [":pcre2test", ":testdata"],
-    size = "small",
-)
+    data = [
+        ":pcre2test",
+        ":testdata",
+    ],
+)