gopls/internal/lsp/cache: disable strict analysis while we fix panics

We now understand the longstanding race causing panics in gopls analysis
(the cache key for analysis handles is not correct, and can lead to
cache hits for analysis of stale packages).

It will take a little while to redesign our analysis caching, the
simplest solution being to hang analysis results off of the actual
package they are analyzing. In the meantime, suppress the panic as
before, to eliminate flakes.

For golang/go#55201
For golang/go#56035

Change-Id: I96600f186f9f31b67dae10c0a95a14fa73630571
Reviewed-on: https://go-review.googlesource.com/c/tools/+/442794
Run-TryBot: Robert Findley <[email protected]>
Reviewed-by: Alan Donovan <[email protected]>
gopls-CI: kokoro <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>

Author: findleyr

gopls/internal/lsp/cache/analysis.go

@@ -258,7 +258,12 @@ func actionImpl(ctx context.Context, snapshot *snapshot, deps []*actionHandle, a
 				// discover this problem in regular packages.
 				// For command-line-arguments we quietly abort the analysis
 				// for now since we already know there is a bug.
-				errorf := bug.Errorf // report this discovery
+
+				// Temporarily disable bug reporting due to golang/go#56035: using
+				// bug.Errorf causes too many test flakes.
+				// TODO(rfindley): switch back to bug.Errorf once panics are fixed.
+				errorf := fmt.Errorf
+
 				if source.IsCommandLineArguments(pkg.ID()) {
 					errorf = fmt.Errorf // suppress reporting
 				}
@@ -364,9 +369,9 @@ func actionImpl(ctx context.Context, snapshot *snapshot, deps []*actionHandle, a
 				// An Analyzer crashed. This is often merely a symptom
 				// of a problem in package loading.
 				//
-				// We believe that CL 420538 may have fixed these crashes, so enable
-				// strict checks in tests.
-				const strict = true
+				// We are aware of a likely cause for these panics: the actionHandle
+				// cache key is not correct. In the meantime, disable strict mode.
+				const strict = false
 				if strict && bug.PanicOnBugs && analyzer.Name != "fact_purity" {
 					// During testing, crash. See issues 54762, 56035.
 					// But ignore analyzers with known crash bugs: