internal/lsp/source: add the nilness analyzer
Fixes golang/go#44627
Change-Id: I4291b419862c7b7df8eff988abe7ab38d03e6189
Reviewed-on: https://go-review.googlesource.com/c/tools/+/299131
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Trust: Rebecca Stambler <rstambler@golang.org>
Trust: Robert Findley <rfindley@google.com>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
diff --git a/gopls/doc/analyzers.md b/gopls/doc/analyzers.md
index 6a25f30..e067d0c 100644
--- a/gopls/doc/analyzers.md
+++ b/gopls/doc/analyzers.md
@@ -208,6 +208,46 @@
**Enabled by default.**
+## **nilness**
+
+check for redundant or impossible nil comparisons
+
+The nilness checker inspects the control-flow graph of each function in
+a package and reports nil pointer dereferences, degenerate nil
+pointers, and panics with nil values. A degenerate comparison is of the form
+x==nil or x!=nil where x is statically known to be nil or non-nil. These are
+often a mistake, especially in control flow related to errors. Panics with nil
+values are checked because they are not detectable by
+
+ if r := recover(); r != nil {
+
+This check reports conditions such as:
+
+ if f == nil { // impossible condition (f is a function)
+ }
+
+and:
+
+ p := &v
+ ...
+ if p != nil { // tautological condition
+ }
+
+and:
+
+ if p == nil {
+ print(*p) // nil dereference
+ }
+
+and:
+
+ if p == nil {
+ panic(p)
+ }
+
+
+**Disabled by default. Enable it by setting `"analyses": {"nilness": true}`.**
+
## **printf**
check consistency of Printf format strings and arguments
diff --git a/internal/lsp/source/api_json.go b/internal/lsp/source/api_json.go
index aa7b518..8f72405 100755
--- a/internal/lsp/source/api_json.go
+++ b/internal/lsp/source/api_json.go
@@ -392,6 +392,11 @@
Default: "true",
},
{
+ Name: "\"nilness\"",
+ Doc: "check for redundant or impossible nil comparisons\n\nThe nilness checker inspects the control-flow graph of each function in\na package and reports nil pointer dereferences, degenerate nil\npointers, and panics with nil values. A degenerate comparison is of the form\nx==nil or x!=nil where x is statically known to be nil or non-nil. These are\noften a mistake, especially in control flow related to errors. Panics with nil\nvalues are checked because they are not detectable by\n\n\tif r := recover(); r != nil {\n\nThis check reports conditions such as:\n\n\tif f == nil { // impossible condition (f is a function)\n\t}\n\nand:\n\n\tp := &v\n\t...\n\tif p != nil { // tautological condition\n\t}\n\nand:\n\n\tif p == nil {\n\t\tprint(*p) // nil dereference\n\t}\n\nand:\n\n\tif p == nil {\n\t\tpanic(p)\n\t}\n",
+ Default: "false",
+ },
+ {
Name: "\"printf\"",
Doc: "check consistency of Printf format strings and arguments\n\nThe check applies to known functions (for example, those in package fmt)\nas well as any detected wrappers of known functions.\n\nA function that wants to avail itself of printf checking but is not\nfound by this analyzer's heuristics (for example, due to use of\ndynamic calls) can insert a bogus call:\n\n\tif false {\n\t\t_ = fmt.Sprintf(format, args...) // enable printf checking\n\t}\n\nThe -funcs flag specifies a comma-separated list of names of additional\nknown formatting functions or methods. If the name contains a period,\nit must denote a specific function using one of the following forms:\n\n\tdir/pkg.Function\n\tdir/pkg.Type.Method\n\t(*dir/pkg.Type).Method\n\nOtherwise the name is interpreted as a case-insensitive unqualified\nidentifier such as \"errorf\". Either way, if a listed name ends in f, the\nfunction is assumed to be Printf-like, taking a format string before the\nargument list. Otherwise it is assumed to be Print-like, taking a list\nof arguments with no format string.\n",
Default: "true",
@@ -910,6 +915,11 @@
Default: true,
},
{
+ Name: "nilness",
+ Doc: "check for redundant or impossible nil comparisons\n\nThe nilness checker inspects the control-flow graph of each function in\na package and reports nil pointer dereferences, degenerate nil\npointers, and panics with nil values. A degenerate comparison is of the form\nx==nil or x!=nil where x is statically known to be nil or non-nil. These are\noften a mistake, especially in control flow related to errors. Panics with nil\nvalues are checked because they are not detectable by\n\n\tif r := recover(); r != nil {\n\nThis check reports conditions such as:\n\n\tif f == nil { // impossible condition (f is a function)\n\t}\n\nand:\n\n\tp := &v\n\t...\n\tif p != nil { // tautological condition\n\t}\n\nand:\n\n\tif p == nil {\n\t\tprint(*p) // nil dereference\n\t}\n\nand:\n\n\tif p == nil {\n\t\tpanic(p)\n\t}\n",
+ Default: false,
+ },
+ {
Name: "printf",
Doc: "check consistency of Printf format strings and arguments\n\nThe check applies to known functions (for example, those in package fmt)\nas well as any detected wrappers of known functions.\n\nA function that wants to avail itself of printf checking but is not\nfound by this analyzer's heuristics (for example, due to use of\ndynamic calls) can insert a bogus call:\n\n\tif false {\n\t\t_ = fmt.Sprintf(format, args...) // enable printf checking\n\t}\n\nThe -funcs flag specifies a comma-separated list of names of additional\nknown formatting functions or methods. If the name contains a period,\nit must denote a specific function using one of the following forms:\n\n\tdir/pkg.Function\n\tdir/pkg.Type.Method\n\t(*dir/pkg.Type).Method\n\nOtherwise the name is interpreted as a case-insensitive unqualified\nidentifier such as \"errorf\". Either way, if a listed name ends in f, the\nfunction is assumed to be Printf-like, taking a format string before the\nargument list. Otherwise it is assumed to be Print-like, taking a list\nof arguments with no format string.\n",
Default: true,
diff --git a/internal/lsp/source/options.go b/internal/lsp/source/options.go
index 3f50eac..d36d129 100644
--- a/internal/lsp/source/options.go
+++ b/internal/lsp/source/options.go
@@ -31,6 +31,7 @@
"golang.org/x/tools/go/analysis/passes/loopclosure"
"golang.org/x/tools/go/analysis/passes/lostcancel"
"golang.org/x/tools/go/analysis/passes/nilfunc"
+ "golang.org/x/tools/go/analysis/passes/nilness"
"golang.org/x/tools/go/analysis/passes/printf"
"golang.org/x/tools/go/analysis/passes/shadow"
"golang.org/x/tools/go/analysis/passes/shift"
@@ -1139,6 +1140,7 @@
atomicalign.Analyzer.Name: {Analyzer: atomicalign.Analyzer, Enabled: true},
deepequalerrors.Analyzer.Name: {Analyzer: deepequalerrors.Analyzer, Enabled: true},
fieldalignment.Analyzer.Name: {Analyzer: fieldalignment.Analyzer, Enabled: false},
+ nilness.Analyzer.Name: {Analyzer: nilness.Analyzer, Enabled: false},
shadow.Analyzer.Name: {Analyzer: shadow.Analyzer, Enabled: false},
sortslice.Analyzer.Name: {Analyzer: sortslice.Analyzer, Enabled: true},
testinggoroutine.Analyzer.Name: {Analyzer: testinggoroutine.Analyzer, Enabled: true},
