Optimize CcInfo computation (#4020)

This shows up around 4% of buildbuddy analysis phase
<img width="1728" alt="image"
src="https://github.com/user-attachments/assets/18344d22-ea21-4dbf-8542-2cf2763fa2ba">

After this change, it goes away.

It seems like Bazel is able to make this lazy, which is good since it's
only used for building LINKMODE_C_ARCHIVE/LINKMODE_C_SHARED which is
fairly rare.

**What type of PR is this?**
Performance improvement

**What does this PR do? Why is it needed?**
Avoid computing CcInfo for every intermediate library when it's not
needed

**Which issues(s) does this PR fix?**

Fixes #

**Other notes for review**

Author: dzbarsky

docs/go/core/rules.md

@@ -172,12 +172,6 @@ def as_tuple(v):
         return tuple(v.to_list())
     fail("as_tuple failed on {}".format(v))
 
-_STRUCT_TYPE = type(struct())
-
-def is_struct(v):
-    """Returns true if v is a struct."""
-    return type(v) == _STRUCT_TYPE
-
 def count_group_matches(v, prefix, suffix):
     """Counts reluctant substring matches between prefix and suffix.
 

go/private/common.bzl

@@ -49,7 +49,6 @@ load(
     "COVERAGE_OPTIONS_DENYLIST",
     "GO_TOOLCHAIN",
     "as_iterable",
-    "is_struct",
 )
 load(
     ":mode.bzl",
@@ -282,7 +281,6 @@ def _library_to_source(go, attr, library, coverage_instrumented):
         "cxxopts": _expand_opts(go, "cxxopts", getattr(attr, "cxxopts", [])),
         "clinkopts": _expand_opts(go, "clinkopts", getattr(attr, "clinkopts", [])),
         "cgo_exports": [],
-        "cc_info": None,
         "pgoprofile": getattr(attr, "pgoprofile", None),
     }
 
@@ -310,11 +308,10 @@ def _library_to_source(go, attr, library, coverage_instrumented):
             # sources. compilepkg will catch these instead.
             if f.extension in ("c", "cc", "cxx", "cpp", "hh", "hpp", "hxx"):
                 fail("source {} has C/C++ extension, but cgo was not enabled (set 'cgo = True')".format(f.path))
+
     if library.resolve:
         library.resolve(go, attr, source, _merge_embed)
 
-    source["cc_info"] = _collect_cc_infos(attr_deps + generated_deps, source["cdeps"])
-
     return GoSource(**source)
 
 def _collect_runfiles(go, data, deps):
@@ -327,19 +324,6 @@ def _collect_runfiles(go, data, deps):
         [get_source(t).runfiles for t in deps],
     )
 
-def _collect_cc_infos(deps, cdeps):
-    cc_infos = []
-    for dep in cdeps:
-        if CcInfo in dep:
-            cc_infos.append(dep[CcInfo])
-    for dep in deps:
-        # dep may be a struct, which doesn't support indexing by providers.
-        if is_struct(dep):
-            continue
-        if GoSource in dep:
-            cc_infos.append(dep[GoSource].cc_info)
-    return cc_common.merge_cc_infos(cc_infos = cc_infos)
-
 def _check_binary_dep(go, dep, edge):
     """Checks that this rule doesn't depend on a go_binary or go_test.
 

go/private/context.bzl

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-# A represenatation of the inputs to a go package.
+# A representation of the inputs to a go package.
 # This is a configuration independent provider.
 # You must call resolve with a mode to produce a GoSource.
 # See go/providers.rst#GoLibrary for full documentation.