Also retrieve file's package when fast-scanning for imports

[jhump]

This augments the experimental fast-scanner imports.ScanForImports to also return the package for each scanned file.

[bufdev]

I might move this to fastscan.Scan or something, but all good for me!

[jhump]

I might move this to fastscan.Scan or something

Sounds like a good idea, so I went ahead and did this.

[bufdev]

Something about this change broke the integration tests for the new workspaces - I think it is that some imports are no longer getting picked up:

https://github.com/bufbuild/buf/commits/bufmod

cd path/to/buf-checkout
git fetch origin
git checkout bufmod
git checkout a7de4fb19a7ea110e8ccecc992eaff4bfbb2d98c # right before i reverted protocompile to before this PR
go test ./private/buf/bufworkspace

--- FAIL: TestBasic (0.01s)
    dagtest.go:64:
        	Error Trace:	/Users/foo/dev/buf/private/pkg/dag/dagtest/dagtest.go:64
        	           				/Users/foo/dev/buf/private/buf/bufworkspace/workspace_test.go:76
        	Error:      	Not equal:
        	           	expected: []dagtest.ExpectedNode[string]{dagtest.ExpectedNode[string]{Key:"buf.testing/acme/bond", Outbound:[]string{"buf.testing/acme/date", "buf.testing/acme/geo", "buf.testing/acme/money"}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/date", Outbound:[]string{"buf.testing/acme/extension"}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/extension", Outbound:[]string{}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/geo", Outbound:[]string{}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/money", Outbound:[]string{}}, dagtest.ExpectedNode[string]{Key:"finance/portfolio/proto", Outbound:[]string{"buf.testing/acme/bond", "buf.testing/acme/extension"}}}
        	           	actual  : []dagtest.ExpectedNode[string]{dagtest.ExpectedNode[string]{Key:"buf.testing/acme/bond", Outbound:[]string{"buf.testing/acme/date"}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/date", Outbound:[]string{"buf.testing/acme/extension"}}, dagtest.ExpectedNode[string]{Key:"buf.testing/acme/extension", Outbound:[]string{}}, dagtest.ExpectedNode[string]{Key:"finance/portfolio/proto", Outbound:[]string{"buf.testing/acme/bond"}}}
        	           	
        	           	Diff:
        	           	--- Expected
        	           	+++ Actual
        	           	@@ -1,8 +1,6 @@
        	           	-([]dagtest.ExpectedNode[string]) (len=6) {
        	           	+([]dagtest.ExpectedNode[string]) (len=4) {
        	           	 (dagtest.ExpectedNode[string]) {
        	           	  Key: (string) (len=21) "buf.testing/acme/bond",
        	           	-  Outbound: ([]string) (len=3) {
        	           	-   (string) (len=21) "buf.testing/acme/date",
        	           	-   (string) (len=20) "buf.testing/acme/geo",
        	           	-   (string) (len=22) "buf.testing/acme/money"
        	           	+  Outbound: ([]string) (len=1) {
        	           	+   (string) (len=21) "buf.testing/acme/date"
        	           	  }
        	           	@@ -21,16 +19,5 @@
        	           	 (dagtest.ExpectedNode[string]) {
        	           	-  Key: (string) (len=20) "buf.testing/acme/geo",
        	           	-  Outbound: ([]string) {
        	           	-  }
        	           	- },
        	           	- (dagtest.ExpectedNode[string]) {
        	           	-  Key: (string) (len=22) "buf.testing/acme/money",
        	           	-  Outbound: ([]string) {
        	           	-  }
        	           	- },
        	           	- (dagtest.ExpectedNode[string]) {
        	           	  Key: (string) (len=23) "finance/portfolio/proto",
        	           	-  Outbound: ([]string) (len=2) {
        	           	-   (string) (len=21) "buf.testing/acme/bond",
        	           	-   (string) (len=26) "buf.testing/acme/extension"
        	           	+  Outbound: ([]string) (len=1) {
        	           	+   (string) (len=21) "buf.testing/acme/bond"
        	           	  }
        	Test:       	TestBasic
FAIL
FAIL	github.com/bufbuild/buf/private/buf/bufworkspace	0.243s
FAIL

Thats all the info I have right now, but here is where it is called: https://github.com/bufbuild/buf/blob/a7de4fb19a7ea110e8ccecc992eaff4bfbb2d98c/private/bufpkg/bufmodule/module_set.go#L472 and here are the test files: https://github.com/bufbuild/buf/tree/a7de4fb19a7ea110e8ccecc992eaff4bfbb2d98c/private/buf/bufworkspace/testdata/basic https://github.com/bufbuild/buf/blob/a7de4fb19a7ea110e8ccecc992eaff4bfbb2d98c/private/buf/bufworkspace/workspace_test.go

[jhump]

To close the loop on the issue brought up above: this turned out to be an error in the test source code that was being used. The change in this PR that tickled it was that this change made the parsing of imports a little bit more precise, which means it could fail in the face of certain kinds of syntax errors in the source. Fixing the syntax errors in the test source resolved the issue.

See #214 for more updates to this package. When these kinds of syntax errors are identified, they will be returned to the caller. That PR also adds some tests, which caught an issue in this package with handling of public and weak imports.