x/tools/gopls: diagnostics doesn't update when build tags specification changes

[hyangah]

When removing the build tags from a file to include the file in the build set,
the diagnostics don't update. I am guessing this is probably similar to
other diagnostics related bug reports involving new file creation, but the
repro step is slightly different, I decided to report this.

--- foo/foo.go ---
// +build foo

package foo
var Foo = 1

--- foo/bar.go ---
package foo
var Bar = Foo

Gopls will report the reference to Foo from bar.go is undefined.

Now remove the build tag // +build foo from the foo/foo.go and save the file.
Diagnostics on bar.go remain unchanged. Editing/saving bar.go will not change stale diagnostics/symbol info either.

Used go1.14.1, gopls built from master (e9a00ec)
Gopls log is:

[Info - 3:43:19 PM] 2020/04/28 15:43:19
message="Build info\n----------\ngolang.org/x/tools/gopls master\n golang.org/x/tools/gopls@(devel)\n github.com/BurntSushi/[email protected] h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ=\n github.com/sergi/[email protected] h1:we8PVUC3FE2uYfodKH/nBHMSetSfHDR6scGdBi+erh0=\n golang.org/x/[email protected] h1:KU7oHjnv3XNWfa5COkzUifxZmxp1TyI7ImMXqFxLwvQ=\n golang.org/x/[email protected] h1:vcxGaoTs7kV8m5Np9uUNQin4BrLOthgV7252N8V+FwY=\n golang.org/x/[email protected] => ../\n golang.org/x/[email protected] h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=\n honnef.co/go/[email protected] h1:sXmLre5bzIR6ypkjXCDI3jHPssRhc8KD/Ome589sc3U=\n mvdan.cc/xurls/[email protected] h1:KaMb5GLhlcSX+e+qhbRJODnUUBvlw01jt4yrjFIHAuA=\n\nGo info\n-------\ngo version go1.14.1 darwin/amd64\n\n"
[Info - 3:43:19 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=0
directory=/Users/hakim/scratch/foo
query=[./... builtin]
packages=2
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go env for /Users/hakim/scratch/foo\n(valid build configuration = true)\n(build flags: [-modfile=/var/folders/bw/6r6k9d113sv1_vvzk_1kfxbm001py5/T/go.foo.992652678.mod])\nGO111MODULE=""\nGOARCH="amd64"\nGOBIN=""\nGOCACHE="/Users/hakim/Library/Caches/go-build"\nGOENV="/Users/hakim/Library/Application Support/go/env"\nGOEXE=""\nGOFLAGS=""\nGOHOSTARCH="amd64"\nGOHOSTOS="darwin"\nGOINSECURE=""\nGONOPROXY=""\nGONOSUMDB=""\nGOOS="darwin"\nGOPATH="/Users/hakim/go"\nGOPRIVATE=""\nGOPROXY="https://proxy.golang.org,direct\"\nGOROOT=\"/usr/local/go\"\nGOSUMDB=\"sum.golang.org\"\nGOTMPDIR=\"\"\nGOTOOLDIR=\"/usr/local/go/pkg/tool/darwin_amd64\"\nGCCGO=\"gccgo\"\nAR=\"ar\"\nCC=\"clang\"\nCXX=\"clang++\"\nCGO_ENABLED=\"1\"\nGOMOD=\"/Users/hakim/scratch/foo/go.mod\"\nCGO_CFLAGS=\"-g -O2"\nCGO_CPPFLAGS=""\nCGO_CXXFLAGS="-g -O2"\nCGO_FFLAGS="-g -O2"\nCGO_LDFLAGS="-g -O2"\nPKG_CONFIG="pkg-config"\nGOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/bw/6r6k9d113sv1_vvzk_1kfxbm001py5/T/go-build444620568=/tmp/go-build -gno-record-gcc-switches -fno-common"\n"
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=1
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Error - 3:43:20 PM] 2020/04/28 15:43:19
message="DocumentSymbols failed"
error=getting file for DocumentSymbols: no PackageHandles
URI=file:///Users/hakim/scratch/foo/foo.go
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=1
package_path="foo"
files=[/Users/hakim/scratch/foo/bar.go]
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=1
directory=/Users/hakim/scratch/foo
query=[foo]
packages=1
[Error - 3:43:20 PM] 2020/04/28 15:43:19
message="failed to compute document links"
error=no PackageHandles
URI=file:///Users/hakim/scratch/foo/foo.go
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=1
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Info - 3:43:20 PM] 2020/04/28 15:43:19
message="go/packages.Load"
snapshot=1
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Info - 3:43:20 PM] 2020/04/28 15:43:20
message="go/packages.Load"
snapshot=1
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Info - 3:43:31 PM] 2020/04/28 15:43:31
message="go/packages.Load"
snapshot=2
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Info - 3:43:31 PM] 2020/04/28 15:43:31
message="go/packages.Load"
snapshot=2
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Info - 3:43:34 PM] 2020/04/28 15:43:34
message="go/packages.Load"
snapshot=2
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Error - 3:43:34 PM] 2020/04/28 15:43:34
message="failed to compute document links"
error=no PackageHandles
URI=file:///Users/hakim/scratch/foo/foo.go
[Info - 3:43:34 PM] 2020/04/28 15:43:34
message="go/packages.Load"
snapshot=2
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=0
[Error - 3:43:34 PM] 2020/04/28 15:43:34
message="DocumentSymbols failed"
error=getting file for DocumentSymbols: no PackageHandles
URI=file:///Users/hakim/scratch/foo/foo.go
[Info - 3:43:51 PM] 2020/04/28 15:43:51
message="go/packages.Load"
snapshot=3
directory=/Users/hakim/scratch/foo
query=[file=/Users/hakim/scratch/foo/foo.go]
packages=1
[Info - 3:43:51 PM] 2020/04/28 15:43:51
message="go/packages.Load"
snapshot=3
package_path="foo"
files=[/Users/hakim/scratch/foo/bar.go /Users/hakim/scratch/foo/foo.go]
[Error - 3:43:52 PM] 2020/04/28 15:43:52
message="DocumentSymbols failed"
error=getting file for DocumentSymbols: no ParseGoHandle for file:///Users/hakim/scratch/foo/foo.go
URI=file:///Users/hakim/scratch/foo/foo.go
[Error - 3:43:55 PM] 2020/04/28 15:43:55
message="DocumentSymbols failed"
error=getting file for DocumentSymbols: no ParseGoHandle for file:///Users/hakim/scratch/foo/foo.go
URI=file:///Users/hakim/scratch/foo/foo.go
[Info - 3:44:01 PM] 2020/04/28 15:44:01
message="background imports cache refresh starting"
[Info - 3:44:01 PM] 2020/04/28 15:44:01
message="background refresh finished after 293.666827ms"

[myitcv]

Likely related: #37101

[gopherbot]

Change https://golang.org/cl/296549 mentions this issue: internal/lsp/cache: invalidate metadata on magic comment changes