[go] cgo: Check presence of a C compiler

Andrey Bokhanko (Gerrit)

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Mar 12, 2021, 11:25:08 AM3/12/21

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cgo: Check presence of a C compiler

Currently we print a cryptic message is a C compiler doesn't exist.
This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1
---
M src/cmd/cgo/main.go
1 file changed, 10 insertions(+), 0 deletions(-)

diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index 5767c54..c7755b5 100644
--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -20,6 +20,7 @@
 	"io"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"reflect"
 	"runtime"
@@ -302,6 +303,15 @@
 
 	p := newPackage(args[:i])
 
+	// We need a C compiler to be available. Check this.
+	gccName := p.gccBaseCmd()[0]
+	_, err := exec.LookPath(gccName)
+	if err != nil {
+		fatalf("C compiler '%s' can't be found. Check that you have a C compiler "+
+			"installed and added to your PATH.", gccName)
+		os.Exit(2)
+	}
+
 	// Record CGO_LDFLAGS from the environment for external linking.
 	if ldflags := os.Getenv("CGO_LDFLAGS"); ldflags != "" {
 		args, err := splitQuoted(ldflags)

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Andrey Bokhanko (Gerrit)

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Mar 12, 2021, 11:36:27 AM3/12/21

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Andrey Bokhanko uploaded patch set #2 to this change.

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cgo: Check presence of a C compiler

Currently we print a cryptic message is a C compiler doesn't exist.
This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1
---
M src/cmd/cgo/main.go
1 file changed, 10 insertions(+), 0 deletions(-)

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David Chase (Gerrit)

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Mar 12, 2021, 12:20:55 PM3/12/21

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2 comments:

Patchset:
- Patch Set #2:
  Thanks, this is good. I added Ian as a reviewer, he might have better words.
File src/cmd/cgo/main.go:
- Patch Set #2, Line 310:

C compiler \"%s\" can't be found. Check that you have a C compiler "+

- ```
			"installed and added to your PATH.
```

- Definitely an improvement. I think I would add mention of cgo so that when cgo is invoked behind the curtains (for example, in the case of race detection), it provides a clue to reduce the size of a user's problem space.
```
So, maybe:
"C compiler \"%s\" can't be found for cgo command. Check that you have a C compiler "+
```

- ```
			"installed and added to your PATH."
```

- Ian, or you, may have a better way to phrase this.

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Andrey Bokhanko (Gerrit)

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Mar 15, 2021, 3:48:24 AM3/15/21

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1 comment:

File src/cmd/cgo/main.go:

Patch Set #2, Line 310:

C compiler \"%s\" can't be found. Check that you have a C compiler "+
			"installed and added to your PATH.

- Definitely an improvement. […]
  Thanks!
  As for mentioning cgo, fatalf already prints "cgo:" prefix, so on my Linux box the message looks like this:
  cgo: C compiler "gcc" can't be found. Check that you have a C compiler installed and added to your PATH.

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David Chase (Gerrit)

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Mar 15, 2021, 11:00:53 AM3/15/21

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Patch set 2:Code-Review +2

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1 comment:

File src/cmd/cgo/main.go:

Patch Set #2, Line 310:

C compiler \"%s\" can't be found. Check that you have a C compiler "+
			"installed and added to your PATH.

- Thanks! […]
  Great!
  I'd like to wait a hair longer for Ian, but for now, LGTM.
  Actually I think we have to anyway, might need a second "trust" vote, not sure.

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Ian Lance Taylor (Gerrit)

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Mar 15, 2021, 5:28:16 PM3/15/21

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3 comments:

Commit Message:
- Patch Set #2, Line 7: cgo: Check presence of a C compiler
  cmd/cgo: check whether C compiler exists
File src/cmd/cgo/main.go:
- Patch Set #2, Line 310: fatalf("C compiler \"%s\" can't be found. Check that you have a C compiler "+
  Use %q instead of \"%s\".
  Also no need for a line break here, there is no line length limit.
- Patch Set #2, Line 311: "installed and added to your PATH.", gccName)
```
I think a message like
    fatalf("C compiler %q not found: %v", gccName, err)
will suffice.  The error returned by exec.LookPath will help.
```

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Andrey Bokhanko (Gerrit)

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Mar 16, 2021, 2:46:04 AM3/16/21

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Andrey Bokhanko uploaded patch set #3 to this change.

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cgo: Check presence of a C compiler

Currently we print a cryptic message if a C compiler doesn't exist.


This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1
---
M src/cmd/cgo/main.go

1 file changed, 9 insertions(+), 0 deletions(-)

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Andrey Bokhanko (Gerrit)

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Mar 16, 2021, 2:48:14 AM3/16/21

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2 comments:

Patchset:
- Patch Set #2:
  Ian, thanks for the review! Fixed you comment; please take a look.
File src/cmd/cgo/main.go:
- Patch Set #2, Line 311: "installed and added to your PATH.", gccName)
  I think a message like […]
  Done as you suggested. Now the message looks like so (on my Linux box):
  $ export CC=clang
  $ go build ./issue44271.go
  # runtime/cgo
  cgo: C compiler "clang" not found: exec: "clang": executable file not found in $PATH

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Andrey Bokhanko (Gerrit)

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Mar 16, 2021, 2:49:19 AM3/16/21

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1 comment:

File src/cmd/cgo/main.go:
- Patch Set #2, Line 310: fatalf("C compiler \"%s\" can't be found. Check that you have a C compiler "+
  Use %q instead of \"%s\". […]
  Fixed

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Ian Lance Taylor (Gerrit)

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Mar 16, 2021, 8:25:30 PM3/16/21

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1 comment:

Commit Message:

- Patch Set #2, Line 7: cgo: Check presence of a C compiler
  cmd/cgo: check whether C compiler exists

- Please update the topic sentence as suggested. Thanks. See https://golang.org/wiki/CommitMessage.

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Andrey Bokhanko (Gerrit)

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Mar 17, 2021, 3:52:13 AM3/17/21

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Andrey Bokhanko uploaded patch set #4 to this change.

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cgo: check whether C compiler exists


Currently we print a cryptic message if a C compiler doesn't exist.
This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1
---
M src/cmd/cgo/main.go
1 file changed, 9 insertions(+), 0 deletions(-)

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Andrey Bokhanko (Gerrit)

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Mar 17, 2021, 3:53:08 AM3/17/21

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1 comment:

Commit Message:

- Patch Set #2, Line 7: cgo: Check presence of a C compiler

- Please update the topic sentence as suggested. Thanks. See https://golang.org/wiki/CommitMessage.
  Done

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Andrey Bokhanko (Gerrit)

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Mar 17, 2021, 3:53:54 AM3/17/21

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Andrey Bokhanko uploaded patch set #5 to this change.

View Change

cmd/cgo: check whether C compiler exists



Currently we print a cryptic message if a C compiler doesn't exist.
This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1
---
M src/cmd/cgo/main.go
1 file changed, 9 insertions(+), 0 deletions(-)

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Ian Lance Taylor (Gerrit)

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Mar 17, 2021, 3:53:34 PM3/17/21

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Patch set 5:Run-TryBot +1

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Ian Lance Taylor (Gerrit)

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Mar 17, 2021, 4:29:13 PM3/17/21

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Patch set 5:Code-Review +2

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1 comment:

Patchset:
- Patch Set #5:
  Thanks.

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Ian Lance Taylor (Gerrit)

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Mar 17, 2021, 4:29:27 PM3/17/21

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Ian Lance Taylor submitted this change.

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Approvals:
  Ian Lance Taylor: Looks good to me, approved; Run TryBots
  David Chase: Looks good to me, approved
  Go Bot: TryBots succeeded

cmd/cgo: check whether C compiler exists

Currently we print a cryptic message if a C compiler doesn't exist.
This patch adds more graceful handling.

Fixes #44271

Change-Id: I44f16ef6eb2853fee22fa1d996e41ec6c9ee82f1

Reviewed-on: https://go-review.googlesource.com/c/go/+/301249
Run-TryBot: Ian Lance Taylor <ia...@golang.org>
TryBot-Result: Go Bot <go...@golang.org>
Reviewed-by: Ian Lance Taylor <ia...@golang.org>
Reviewed-by: David Chase <drc...@google.com>


---
M src/cmd/cgo/main.go
1 file changed, 9 insertions(+), 0 deletions(-)

diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index 5767c54..77ac5e0 100644


--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -20,6 +20,7 @@
 	"io"
 	"io/ioutil"
 	"os"
+	"os/exec"
 	"path/filepath"
 	"reflect"
 	"runtime"

@@ -302,6 +303,14 @@


 
 	p := newPackage(args[:i])
 
+	// We need a C compiler to be available. Check this.
+	gccName := p.gccBaseCmd()[0]
+	_, err := exec.LookPath(gccName)
+	if err != nil {

+		fatalf("C compiler %q not found: %v", gccName, err)


+		os.Exit(2)
+	}
+
 	// Record CGO_LDFLAGS from the environment for external linking.
 	if ldflags := os.Getenv("CGO_LDFLAGS"); ldflags != "" {
 		args, err := splitQuoted(ldflags)

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